I only know PHP. How do I write a Web application in Python?

http://me.veekun.com/blog/2012/05/05/python-faq-webdev/

by jrheard • 14 years ago

230 186 14 years ago

me.veekun.com

prezjordan• 14 years ago

off-topic: love the greek-lettered ordered list.

gcb2• 14 years ago

Say wat you want of php. But it's (insert personal pejorative option) made for it.

Sure Its a_little_inconsistent AndSomewhatChaotic

But all the basics for the web are incredible accessible right away.

With every other language you have to start with a framework.

I find php easier than rails to prototype applications and do fast hacks that need a web face.

It's simply the right tool for the job on those occasions. Of course, later they become huge systems...

eevee20• 14 years ago

That's why e.g. Flask exists: it gives you the basics, plus light structure and templating and routing and XSS protection and deployment options and whatever else. With no setup and no boilerplate.

It's about as much effort as typing `<?php`.

chrisguitarguy• 14 years ago

While that's true (and I do love Flask), PHP comes installed on every discount web host. Deploying a PHP app is as easy as using FTP, deploying a Python app can be -- but doesn't have to be -- complex. I'd say this is the bigger sticking point than the framework.

Obviously Heroku and other PAAS providers are changing the game as far as deployment ease. It should be to see what happens in the next few years on that front.

BrandonM2• 14 years ago

That's a nice sentiment that's completely inaccurate. Even 6 years ago when I first started programming Python, simple Python cgi scripts were very easy to write. It's as simple as:

  print """\
  Content-type: text/html
  
  <html>...</html>"""

With %(var)s interpolation, you can even slap in locals() easily to trivially put variables' values into the page.

eli5• 14 years ago

That doesn't seem like it will scale very well at all. Or am I missing something?

gcb2• 14 years ago

and you think that manually handling headers is more straightforward than php? I disagree.

akkartik• 14 years ago

What's wrong with mysql?

cbg03• 14 years ago

Apparently, it isn't PostgreSQL; If you have no need for Postgres features and you're not familiar with it, sticking to MySQL is fine.

gbog6• 14 years ago

Well you can say the same for windows vs Linux or visual basic vs any other language, and you can also continue using paper glue to attach paintings on the wall.

It is not a matter of what you need, it is a matter of using good tools that will help you do good work, understand better what you do, build durable products, and so on.

Just one example: MySQL will not complain if you add a check constraint but will not actually add it to your schema. That's a very Microsoft-y way to handle things, and should give cold sweat to any coder.

geon• 14 years ago

MySQL was a lot worse before 2004 or so. It wouldn't do transactions, nor proper joins, if I remember correctly.

I think the bad reputation still sticks to it.

Sanddancer• 14 years ago

Honestly, as others pointed out, the multitude of sins of omissions that MySQL has performed over the years. For example, its silently ignoring the foreign key constraints on certain database engines, such as MyISAM. On top of that, the repeated and continuing promises of actually implementing features like foreign keys in many of their database engines, including their high-performance NDB engine, means that the programmer has to do a lot more bookkeeping work on things that are built in on more rational databases.

The multiple database engine mess leads to its own problems compared to engines like postgresql. Do you use the InnoDB engine, and rely on third-party products, like galera, for clustering, or do you use NDB and suffer its weaknesses in referential integrity, and difficulty in configuration?

Finally, you get into issues where MySQL isn't nearly as featureful as PostgreSQL. For example, PostgreSQL supports a multitude of languages for creating server-side procedural functions -- pgsql, perl, python, tcl, etc, whereas MySQL only supports C, and only pre-compiled functions. This limits the utility, and leads to these quite useful features being left by the wayside because numerous coders were weaned on a database that didn't support doing these nice things for them.

While mysql does have certain uses, I'd argue severely that postgresql is a much better designed foundation for working on new projects. The attention to detail, the emphasis on not eating your data, and the level of features means that you can spend more time coding, and in the language you want to use, and less time fiddling with your database software.

ashray• 14 years ago

This guy failed to cover web.py which is one of the fastest ways to start prototyping a web app in python. =/

http://webpy.org/

I personally use it for a small app which returns (and stores) search suggestions from redis.

gbog6• 14 years ago

"MySQL is the PHP of databases". Strange, I just had this sentence popping in my head yesterday. I'm seriously considering writing a list of its wrong doings.

Great article overall.

jrheard• 14 years ago

I'd be interested in reading that list!

AgentConundrum• 14 years ago

Please write that list. I'd be very interested in reading it.

glogla• 14 years ago

Color me as another interested specimen.

gbog6• 14 years ago

I wanted to do that now but did some lego with my kid instead, will keep you 3 informed when done.

zokier4• 14 years ago

Linux is the PHP of Unixes and Apache is the PHP of webservers. And now we have covered the whole LAMP stack :)

Xuzz• 14 years ago

I'd say the necessity of this post is why PHP is as popular as it is. With PHP, there are no package managers I have to install; there is no template language to learn; there is often no version control; there is no "framework"; etc. You just drop in a .php file and, most likely, it will just run. If I need a quick dynamic page on my server, it's much easier to do this in PHP than in Python or Ruby.

Until Python or Ruby have that kind of simplicity, they can't overtake PHP. While it might not be the kind of design that leads to well-designed web apps or even good code, it is the kind of design that leads to more — especially less technical, or, like me, lazy — users. It's up to the developers of those languages if this is even a market they want. There may need to be something new to do the same job as PHP, but better, without the innumerable warts.

eevee20• 14 years ago

Most of the post _isn't_ strictly necessary. You don't need a database to get your feet wet. You don't need to care about XSS for your first throwaway app (though, arguably, you should). I pimp Mako precisely because there's no separate language to learn: the core syntax is just Python.

I tried to describe the _ecosystem_, and I assume any serious PHP application will care about most of the same things.

Here's all you really need: look at http://flask.pocoo.org/ and do that thing it says right there. You don't even need to install a separate web server. (Yeah, yeah, 5.4, I know.)

A "quick dynamic page" is a deployment problem. If you're already running Apache and mod_php, you already have an environment ready to go to serve PHP, so of course it'll be easy for you. I don't run Apache, so PHP doesn't really help me there. (mod_passenger promises to, but I haven't tried it with Python yet.)

lloeki• 14 years ago

Also, http://pow.cx/ (Ruby I know, but it shows such things can be done.)

Also the argument of python/ruby requiring lots of configuration while php would not is just plain bullshit. Making PHP run with Apache (esp. on a windows machine) without stuff like EasyPHP (and this is where you stop comparing apples to oragnes) is by and large tough on the beginner.

conradev2• 14 years ago

I am lucky that I found Flask a while ago, because I was sick of PHP. Flask, jinja2, and uWSGI have since been my best friends.

It took a little while to figure out how to setup a proper web server around those, but the guides are not that complex. Install nginx, darmonize uWSGI with upstart, and configure it. It's funny, in some ways it's easier to use than PHP, because when I am working with the website on my local machine, I can run uWSGI in http mode, no configuration necessary.

The only barrier I see going from PHP to Python or Ruby is managed hosting.

sparknlaunch12• 14 years ago

I agree on the simplicity of php. The barrier to write php is low. All you need is notepad and browser. This may be a transition from writing html.

Compare this to other languages where you need multiple tools before you can even begin.

This doesn't make php better. It just may explain why less people make the jump.

ashconnor• 14 years ago

You also need a server, which I think is one of the crucial components for PHP adoption.

MAMP, XAMPP, WAMP are all really easy to install and you don't need to go into the CL to do anything.

christiangenco2• 14 years ago

All we need is to be able to drop an .erb file in a server and have it instantly rendered with the same magic of .php files. How hard would that be?

Anyone here know how to write plugins for Apache?

thatjoshguy• 14 years ago

You just described python cgi scripts

grey-area2• 14 years ago

Install eruby binary (example given is ubuntu/apache):

  sudo apt-get install ruby libapache2-mod-ruby eruby

Set up your web server to serve it:

  AddHandler rubypage .erb .xhtml
  Action rubypage /cgi-bin/eruby

Start writing pages like this:

  The time is <%= Time.now %>.

The first two steps could be completed by your web host, or done by you once. Obviously you might run into performance issues etc (no idea how well this would work on a live server), but that gets you up and running.

I would point out that most examples you can think of as trivial as that above could just be done with js anyway though, without any dynamic language server-side - the main reason to use a server-side language is to talk to a db or store data, at which point you probably want a framework anyway.

It's already a solved problem really, but people at that level are happy enough on PHP, which for the example above would be almost identical, and for anything more complex a framework is actually useful, and so there's no point in starting this way for many web projects.

grey-area2• 14 years ago

PHP is a template language at heart, so it's a little disingenuous to say that it doesn't force you to learn one, as it does - it's like the erb template language part of rails without the controllers and models. That's fine for what it is, but becomes cumbersome if you want to persist data to the db, handle forms for your models, etc at which point you'd often be better served looking at a framework which does a lot of that work for you. Some are available in PHP, but there are IMHO better options in other languages, and of course, better languages.

Do we need to have one language which scales from 'throw together a web page' to complex web apps? Is it even possible or desirable?

While I think it'd be nice to see Python and Ruby have the number of users that PHP does (though perhaps it wouldn't, with scale comes a worse NSR), it's probably not going to happen, simply because they provide a bit more structure, and many people don't want structure. Those people will be happy with PHP (until they're not, and realise they needed that structure after all), and I don't think Ruby or Python frameworks really have any ambition of catering to them. That's fine and is not a failing on either side. For example no one on the ruby side is going to stop using gems as package management because users starting out might be confused, as they are just too useful. You will find plenty of web frameworks for ruby which are simply one gem to install and off you go though - hardly onerous.

It would certainly be possible to write a better PHP, but all the people who might do that are busy using slightly more complex frameworks which make web development easier.

chernevik• 14 years ago

I am but an egg. But refactoring badly done projects that were started as PHP seems a plausibly common pattern. If Python or Ruby were simpler to start with, there would be more badly done Python / Ruby code, but at least it would refactor in Python / Ruby.

The core Py / Rb community probably wouldn't use simpler quick-and-dirty setups, they have the skills to the same things better and faster already. But making that pathway available would bring more novices to the language, hopefully growing them into Py / Rb. And it would bring more projects into the fold.

zokier4• 14 years ago

CGI scripts have much of PHPs simplicity. You can just drop in a executable file, and depending bit on server configuration, it will just run. With Python a basic hello world would look something like this:

    #!/usr/bin/python
    
    print "Content-type: text/plain"
    print ""
    print "Hello World!"

So 3 lines of "boilerplate", and then you can do anything you want. No extra packages to install or languages to learn. No frameworks necessary.

edit: just as an example of minimal hello world in WSGI:

    def application(environ, start_response):
        start_response('200 OK', [('Content-type', 'text/plain')])
        yield 'Hello World!'

also doesn't need any extra python packages or frameworks. but configuring web server to handle wsgi is bit more involved than cgi.

eli5• 14 years ago

It's a good point that of course python web apps don't have to be complicated. But what you're describing is also not the same as PHP.

raverbashing3• 14 years ago

And therein lies the problem, in WSGI

99% of web sites are hosted in "shared hosting" services

Now compare copying the .php files with configuring WSGI

"No, but WSGI is easy blah blah blah" it doesn't beat copying files And no, settings WSGI is not easy

Also, if you depend on IIS for example, PHP is almost plug'n'play

WSGI on Windows is the definition of "bag of hurt". You can try fastcgi to run on windows, and then you find out flup needs socket.fromfd

The easiest way, if it's your machine, run gunicorn or similar and just make Apache redirect the traffic.

But in shared services it's still way too complicated.

mjschultz3• 14 years ago

Let's look at the PHP version:

    Hello World!

One line. I didn't have to worry about Linux/Windows, knowing HTTP headers or the fact that I need two CRLFs after the last header[1]. I just wanted a page that says "Hello World!" and that's what I got.

Don't get me wrong, I would never choose to write a web app in PHP over python. But it is brain dead simple to go from nothing to something in a few keystrokes. Which is precisely what people just learning to write web apps want (right or wrong).

[1] I can't remember how long it took me to figure out that I needed the second CRLF after the "Content-Type: text/html" when I was learning perl (or even the fact that I needed to specify the Content-Type in the first place).

eevee20• 14 years ago

CGI is easy, yeah, but it has a lot of the same disadvantages as mod_php: no routing, no shared state, slow execution, server misconfiguration can expose your code, possible code execution if you accept uploads, etc.

There are approaches that'll let you dump a WSGI app (with a known interface) anywhere and have the web server still run it. Gosh, someone ought to write about those.

mmaunder• 14 years ago

It took me a while to get used to creating an HTML file and making part of it executable. How utterly obvious and convenient. Templating systems and MVC frameworks now seem like bureaucracy that solve a purely theoretical problem.

evilduck2• 14 years ago

Sure, if all you need is a mildly dynamic page the full blown MVC frameworks that are "standard" for other languages probably seem like bureaucracy to you. But they have their uses, and they also exist for PHP for a good reason. MVC makes massively complicated systems easier to maintain, especially if there's more than one contributor.

Example: I'm responsible for maintaining a "classic" ASP project that's evolved over many years ('98 was the oldest code comment I've found). A report has the wrong value for the record on it. Where do I go to find the source of the error?

You'd say "look at the page that edits that value". Well, sure, but there are dozens of pages that edit that database table plus dozens of other processes that could be altering it (stored procedures, print processes, scheduled tasks, people manually writing SQL statements, etc), looking at all of them would be a huge headache. In a MVC system, I would just go look at the model file of that table and debug the methods it uses to manipulate the database (that's simplified, but it's much less work than the spaghetti alternative).

jiggy20115• 14 years ago

There appears to be currently ongoing some sort of shift in web development.

At the top end of the scale , people are creating more sophisticated "app like" websites that use sophisticated platforms like AWS and "serious" programming like Scala/Java/Ruby/Python/jQuery etc. Because once you have decided to invest serious money in your web development you want to use the best tech you can and build a very "bespoke" online experience.

However at the lower end, sites that would have 5 years ago been build using static HTML with a smattering of PHP and be run on low end shared hosting are being devoured by various platforms. For example rather than hire a webdesigner you can have a facebook fan page or wordpress blog for free (possibly paying someone to customise the CSS in a template for you). As another example in my area there are various services aimed at the takeaway business that provide a turnkey website with an online menu, opening hours, maps etc.

To be honest, working in the low end of the web dev market has always been a nightmare as this is where you will get shaky clients who can't articulate what they want and hardly want to pay anything for it.

If I was going to go back into website development for a business I would be far more interested in finding common requirements for a particular market segment and building something turnkey to sell to 1000+ customers at $20-100 per month where they can upload their own logo and change a bit of the CSS.

bkj123• 14 years ago

Regarding your last point... are you talking 'turnkey' as in something like 37 Signal's Basecamp?

FuzzyDunlop• 14 years ago

> "With PHP ... there is no template language to learn"

While this might be nice for the beginner getting started, it's also a brilliant way to encourage bad habits in people who want to turn it into a career.

Leaving the "PHP is a templating language" pedantry aside, this 'benefit' encourages the aspiring developer to not bother separating concerns. Just go ahead and throw HTML into PHP and vice-versa; throw all your database logic, SQL, and connection details into those self-same files that are being served; leave XSS vulnerabilities in all your code because you probably weren't told to wrap your output in `htmlspecialchars` or whatever.

Shit like that needs to stop. But as the barrier to entry is so low, the same mistakes will be repeated ad infinitum. I would love to figure out a way to introduce a beginner coder to a language, without scaring them off, but without being lax with security and separation of concerns.

That being said, I do agree about frameworks, but I also think that this is because there is no "one true framework" for PHP (Zend, Symfony and Cake don't fit the bill, I don't think). There's no Rails, or Django, and there's no Sinatra or Flask as a minimal alternative. PHP is dire for framework development, not because of the language, but because so many groups of developers are trying to re-invent the same framework (but with their own idea of what 'the PHP way' should be - Javatastic bloat like Symfony and Zend, or Rails mimicry with no real understanding of PHP not being anything like Ruby), treading the same ground over and over again, when there could be more collaboration to provide the definitive offering.

If that were to change, and for the better, I might extend my argument to say that such a framework may be a great way to learn PHP, just like Rails was a great way for many to learn Ruby.

capkutay• 14 years ago

I like java for web app development, simply because it has a well-structured api and a massive community of developers who have run in to the majority of the road blocks you will most likely encounter on the way to launching your app.

yolesaber• 14 years ago

What frameworks and platforms would you recommend for web development with java? I am writing my senior project at college in java (mainly because of the wide amount of image processing libraries available) and would love to add web capabilities.

cletus• 14 years ago

I tend to prefer Python/Flask for Web dev to Python but if you are inclined to use Java there's only really one framework that doesn't make me want to tear my eyeballs out.

That framework is Spring MVC.

It is DI, adapters for vendor-specific libraries and utility. It's probably not the easiest thing to start with just because it is so flexible that it can be hard to know where to start. A good "Hello World" Spring MVC 3.1 app would go a long way.

I really would like to use the Play Framework and it's so close to being great but it just falls too far short.

I really liked Play 1.x with Groovy templates. It was simple and it pretty much just worked.

Play 2.x has gone in a radically different (and backwards incompatible) direction. It is now part of Typesafe and the goal of Play 2.x is to make Scala a first-class citizen.

The problem is that many of the niceties of Play are either harder to use or just outright missing in Java Play 2.x (eg AppEngine support and the OAuth client were all present in 1.x and are slated for a future 2.1 release).

There really is a niche for a Java Web framework that like Play ditches the JEE/servlet model in favour of the Rails/Django way of doing things (including dynamic class reloading) but doesn't do it in a way that makes me want to stab myself repeatedly.

This would include playing nice with the Java ecosystem (seriously just use Maven and to hell with SBT).

lmm2• 14 years ago

Wicket, a thousand times wicket. It's so good it makes programming in java worthwhile. Its templating, if you can even call it that, is a quantum leap ahead of everything else: it's actually object oriented, you can write self-contained reusable components in the way you expect, and you get the full benefits of strong typing at every point. I really wish there was something like it for python, but everyone seems to think templates are good enough.

jiggy20115• 14 years ago

Play! Framework.

I've been using it for over a year and I have to say it's the most "rails like" framework out there for Java.

However they have just released play! 2.0 (which I have not used yet). This makes some major changes to the framework and it's not all backward compatible.

I does have a heavy emphasis on Scala now, but you can still code everything using Standard Java if you want, although it does somewhat butcher Java "best practices".

it's default ORM is JPA/Hibernate which works well enough as it gives you a ton of helper functions, it even automatically creates getter/setter method at runtime allowing you to do C# Style properties simply by declaring entity members as public.

swah2• 14 years ago

I'm writing an AJAX webapp using Dropwizard, and seems that I won't be hitting any roadblocks anymore. The devs are very helpful on the google groups as well.

AlexSerov• 14 years ago

http://www.hybridserverpages.com/ Just two days learning curve.

zobzu• 14 years ago

"I only know PHP"

"I just trashed PHP rather harshly"

"I want to learn python"

Well, you're doing it wrong. How can you trash PHP if you know no other languages ?!

You're following articles, posts saying PHP is bad and.. you decide then that's right it's bad!

Ever though about thinking on your own first? Like, actually trying a language (python, why not) then deciding if it's better?

This kind of stuff always amaze me. You know, sheepish.

eevee20• 14 years ago

This is part of an FAQ series. The bolded part ("I only know PHP...") is the question I'm answering.

I'll leave you to contemplate the irony here.

yaix• 14 years ago

Nice littel overview, but...

"Unicode sucks. This is a universal truth."

And here I stopped reading. Unicode is the best thing around, what sucks it that Py2 does not implement it very well. Py3 does, and that is the main reason I really would like to use it and hope Django will soon fully support it. (Because: there are other languages beside the European ones)

eevee20• 14 years ago

Fair point. Correction: working with encodings sucks.

Py3 isn't magnitudes better with Unicode; it's better about converting incoming bytes, and it makes literals into real strings. But the former isn't necessarily a good thing, and you can get the latter with a `__future__` import. Always dying on implicit conversions is definitely nice, though.

adeelk• 14 years ago

Working with encodings is indeed annoying in Python, but it’s not a “universal” problem.

jeltz6• 14 years ago

Working with encoding is not that bad in for example Ruby 1.9. What makes them horrible to work with are the bad design decisions in Python, especially Python 2.

exim• 14 years ago

In python, stay away from default arguments for methods/functions.

EDIT: yes, mutable default values:

http://effbot.org/zone/default-values.htm

espeed5• 14 years ago

Do you mean don't use defaults that contain mutable values?

achristoffersen2• 14 years ago

I have no idea why web2py gotten such a bad rep. I am a beginning webdeveloper and seriously: web2py is a pleasure to work with. Simple to start, deploy, port and hack. It's backwards compatible and has a template language that really is non existant as so far as its pure python.

Compare that to Rails - which is (comparable) hell to set-up and breaks with upgrades etc.

If you want python web development to be simple, web2py is the way to go. Since I don't have a CS degree and I have often been wrong before - there might be a real problem somewhere. But I don't think so. One of the reasons for this is that Jakob Moss removed his web2py bashing from this thread. Didn't edit - removed it: https://www.quora.com/Is-web2py-a-good-Python-web-framework/...

irahul2• 14 years ago

> But I don't think so. One of the reasons for this is that Jakob Moss removed his web2py bashing from this thread. Didn't edit - removed it: https://www.quora.com/Is-web2py-a-good-Python-web-framework/....

What did he remove?

https://www.quora.com/Is-web2py-a-good-Python-web-framework/...

This isn't the first instance of Django/Flask people not agreeing with web2py design and implementation, and they have been vocal about it a couple of times.

http://www.reddit.com/r/Python/comments/ex54j/seeking_clarif...

Look for comments by mitsuhiko(flask dev) and jacobian(django dev).

achristoffersen2• 14 years ago

Sorry - I remembered that I on an earlier occasion couldn't find JKM' answer. It's there now - and I personally don't find it convincing. Again - I am a novice and has no authority here. – I'd edit above if I could. I am sorry that I wrote wrong info.

Thanks for the reddit link. As you say it seems to me most of the flak is from not agreeing on something. But can an oppinion be correct?

And yes: Mitsuhiko seems to be a super cool, clever and friendly guy. In my last project I played around with request. Lovely it was.

Anyways: my point was not to express that web2py is the greatest thing invented since bacon. Only that I don't understand why the python community dislike it so. After all - web2py makes it very easy to build stuff. Hence it will probably attract people to the language. Hence make it more feasible for webhosts to offer python friendly environments. And that should be a good thing? Especially in the context of OP - "how do PHP guy start with python"?

bobsy• 14 years ago

I would love to switch to Python from PHP but I can't. The reason is I keep getting told to learn Python 2. Python 3 has been out for ages!

Basically I am concerned that I will learn something and create app's which within a year will be out of date. I am confused why Python developers are advocating that newbies learn an old and presumably soon to be legacy version of the language.

I remember when this kinda happened with PHP and versions 4 and 5. I still run across hosts who default to PHP4!? WTF? Its 2012!

Is PYthon3 really that new that you shouldn't pick it up or is this developers still refusing to update?

eevee20• 14 years ago

Python 2 versus 3 isn't anything like PHP 4 versus 5.

The problem is that there are a few minor but backwards-incompatible changes to the syntax in py3. Libraries can't update until all their dependencies update. And web frameworks are some of the most complex software with the most dependencies, so they're updating last.

It's still pretty much the same language behaving in the same way, though. If you know Python 2 really well, it'll take all of five minutes to get accustomed to Python 3. Just don't worry about it and learn 2 until people stop telling you otherwise. :)

mkopinsky2• 14 years ago

"Don't worry, migration from Python 2 to 3 is really easy. It'll take 5 minutes to learn."

"Migration for libraries from Python 2 to 3 is really hard. It's taken them a few years and counting."

Luyt• 14 years ago

Python3 isn't much different from Python2. It's not like you have to re-learn Python when you switch from 2 to 3.

In a nutshell: print() has become a function instead of a statement. The standard library has been made more consistent. Built-in iterators are lazy by default. The two string types (str and unicode) are properly redefined as 'bytes' and 'strings'.

getoffmalawn• 14 years ago

In practice, for MOST developers, the changes between 2 and 3 are minimal. Offhand, print is a function, and there's no distinction between unicode strings and ascii strings anymore. If you do a lot of "low level" networking involving byte strings, you'll notice the difference, because you can't just jump between bytes and strings anymore.

It's this distinction that's delaying a lot of networking related libraries from porting to Python 3 - basically, it's going to be a long, buggy journey. Libraries such as Twisted, have very old codebases - old enough that some of the practices aren't the best, even for Python 2 code. Upgrading it to Python 3 will introduce quite a few breakages.

There's a lot more that I can't think of right now, but I'm sure someone else can cover off other differences.

There's no reason not to learn both - I use Python 3 for a few personal projects, and Python 2 for work.

Ingaz2• 14 years ago

Python 3 is not "really that new" and Python 2.6-2.7 is not "old" in any way.

In fact we have: pre-2.4 (really old, preinstalled on old Redhats), 2.4-2.7, 3.x

Python 3 is curing problem with variable visibility (and if you do not write in "pure" functional way - you will never see this problem) and unicode strings. Other differences is not so "revolutionary".

damncabbage3• 14 years ago

> (and if you do not write in "pure" functional way - you will never see this problem)

Could you explain this a little more, please?

JDavo• 14 years ago

For the vast majority of projects, upgrading (or working with both PY2 and PY3 at the same time) is not that big of a deal unless the project you're working on is really, really old (2.3 days). At work we run unittests targeting different python versions and the most time I've spent changing a typically 4k loc project's codebase to work on both 2 and 3 has been around 4 hours. The average around 1.

megaman821• 14 years ago

The differences between Python 2.7 and 3.x are going to be minimal. You can mostly write Python 3.x style code in 2.7 and still have access to all of the libraries that have not ported their code yet.

pbreit3• 14 years ago

> I am concerned that I will learn something and create app's which within a year will be out of date

Don't worry about that. Start with Python 2 and if you ever have to move to Python 3, it will be fairly easy.

The same thing happened in the PHP world during the switch from 3 to 4 and then 4 to 5. The move from Python 2 to 3 will probably be smoother.

languagehacker• 14 years ago

I really don't think it's worth taking this guy seriously. First he writes a worthless and inaccurate lambast of PHP, and now he's trying to "convert" people to Python by telling us Unicode sucks. Get a life.

damncabbage3• 14 years ago

> ... by telling us Unicode sucks.

Could you tell us where he did this?

(I didn't notice it on the first time through; he did say to use Unicode everywhere inside your code, though, and to not do anything rude like converting Unicode to ASCII by stripping non-latin1 characters.)

smacktoward• 14 years ago

Right under the big bold "Unicode" header. The very next line is

> Unicode sucks. This is a universal truth.

(In fairness, I think what he's really getting at is that dealing with Unicode in languages that were created before it became ubiquitous sucks, not Unicode itself. But if you start off your discussion of Unicode with the statement that "Unicode sucks", you shouldn't be surprised if people think your beef is with Unicode rather than with the tools we use to deal with it.)

eevee20• 14 years ago

Who am I trying to convert? The article answers the question asked in the beginning—a question I've been asked several times since writing the PHP article.

Marwy2• 14 years ago

I've seen Flask mentioned here few times. Is Flask better than Bottle?

lclarkmichalek• 14 years ago

In my humble opinion.. Yes. I feel bottle sacrifices just a little too much for the sake of being a single file distribution. The lack of any (mainstream) templating engine might hinder newcomers, and Flask uses one of the best python templating engines around. I also find Flask's documentation to be more extensive and better laid out. Overall I would recommend Flask if you want to write a full featured website, Bottle if you are looking to write some kind of API layer, or similarly bear bones functionality, and will not require many "batteries included".

Marwy2• 14 years ago

You can use Jinja2 with Bottle:

> pip install Jinja2

from bottle import jinja2_template as template

gouranga• 14 years ago

Good article apart from one thing - avoid the hell out of session state. This becomes the dumping ground for all sorts of crap and will slowly knacker your app. You should only persist enough information to identify the user between requests and keep the rest stateless. We do that using encrypted cookies containing the user id, display name and correlation id.

I've just spent 6 months entirely removing session state from an asp.net app and the performance gain is amazing.

wink• 14 years ago

I was thinking this could redeem the author's credibility a little after the PHP rant, but the irrational hatred for Cheetah sounded very familiar.

I only used it in one project, a few years ago, but there's really no bad thing about it I couldn't say about any other templating system in any language I ever tried.

I wouldn't really take offense with that, but while the XSS chapter still has some points, the Sanitizing chapter goes on to bash PHP for a subjective trend of sanitizing (examples?) just to go on and present an example of sanitizing.

In general, it was a decent article, but sadly again much more opinionated than needed. It's one thing to suggest one technology over the other but it doesn't help to make people who actually agree with your point have their eyes rolling every second paragraph. (That the author doesn't like MySQL was to be expected after the PHP rant as it usually goes hand in hand, but showing some real reasons for Postgres over MySQL would have been nice.)

Still the same criticisms apply, I'd wager most people use PHP (or MySQL for the matter) because it's MINDBLOWINGLY AMAZING, but because a) the infrastructure is set up (especially DBAs hate to mix and match in my experience) b) the people at hand can use the language and use it well c) it gets the job done. quickly. sometimes "good enough".

jeltz6• 14 years ago

Explaining why what he does not like about MySQL would have been moving too far from the subject of the article.

And I liked the sanitizing chapter. It explains well why "sanitizing" is a misused word, which should be avoided. Almost always when I see people call it "sanitizing input" they do not seem to know how to handle input correctly.

eevee20• 14 years ago

I don\'t see the problem with \"sanitizing\". It\'s easy: just add a \\ before every quote and the string is totally safe!

eevee20• 14 years ago

I'm kinda the de facto owner of Cheetah for a fairly heavy user of it—quite possibly the heaviest. It may appear-to-work for a small project, but you would not believe the insanity that lurks beneath the surface.

It's been effectively dead for years, anyway, and the author admitted he'd jumped ship for Mako in 2008.

jiggy20115• 14 years ago

Is there any cheap & easy webhosting available for Python?

Occasionally I get commisioned to build small websites ( < 50 visitors per day) and for that I want to be able to build the site in a day or two.

I don't want the hassle/expense of having to setup and run VPS/AWS infastructure. I just want to give someone a bunch of files and say "sign up for some cheap webhosting, ask them to give you a DB called X and upload these".

I usually end up just doing it in PHP, but it has always felt like a poor reason to choose a language with so many warts.

tantalor2• 14 years ago

Heroku is a good choice,

> This quickstart will get you going with Python and the Flask web framework on the Cedar stack. For Django apps, please see the Django quickstart.

https://devcenter.heroku.com/articles/python

It can be very cheap or free at low scale,

> Each application receives 750 free dyno hours per month.

https://devcenter.heroku.com/articles/dynos

evilduck2• 14 years ago

Replying to Jiggy, but can't directly reply since it's dead:

No, a simple Rails app is not very coupled to Heroku.

The deployment process is simpler and pretty unique to Heroku, but it's usually pretty easy to move away from Heroku or deploy in parallel to another location. I actually deploy one app to Heroku and I have an offsite backup process that deploys the same codebase to a NGINX/Passenger setup and clones the production Heroku data to that instance.

Your mileage will vary, of course. If you start using a bunch of Heroku plugins, you'll find it's harder to maintain an easy dual-deploy setup.

bryanh• 14 years ago

You can get close to that with Webfaction (some assembly required) or Heroku.

peter_l_downs• 14 years ago

I've had a lot of great luck with dotcloud.

http://docs.dotcloud.com/services/python/

pbreit3• 14 years ago

By far the easiest way to get started with Python web development is Web2py which comes as a self-contained install where you can get started in 5 minutes. So you automatically get "request" information, big deal.

eevee20• 14 years ago

Flask comes as a self-contained install where you can get started in 5 minutes.

yashchandra• 14 years ago

But Flask is a micro framework while web2py is a full stack framework. Comparing apples to oranges IMHO.

pbreit3• 14 years ago

Flask doesn't help much with the database.

VBprogrammer3• 14 years ago

   The idea is that a transaction starts when a request  starts, and it’s automatically rolled back if there’s an exception. This is behavior you want from the start! It’s half (err, ¼) the point of using a database.

I mostly agreed with the rest of the article but this strikes me as massive blooper. I can see no reason this would be considered good advise.

It's the database equivalent of the GIL, can't figure out what you actually need to lock? Just lock everything!

An example of this going wrong in production, I work in the online gaming (gambling) industry. One of our users won a large jackpot, our code started a transaction, contacted the 3rd party to have them release the funds, recorded the win in the transaction journal, updated the customers balance etc. Then the stored procedure which inserted a row into the outgoing email queue had a small error. This caused all of the database work on our end to rollback.

For what its worth, this was discovered during a reconciliation with the 3rd party and the customer received his winnings.

My point being, this is a horrible way of dealing with database transactions. Only things which are transactional by nature should be carried out within the same transaction. Obviously your code needs to deal with any errors and carry on or report an error as is appropriate.

mbowcock2• 14 years ago

The transaction is internal to the database. It's essentially a list of operations to perform, if something goes wrong it provides a list of things to reverse. If the db transaction fails, then there would need to be some code to handle rolling back operations outside of the database. I don't think db transactions were to fault in your situation.

VBprogrammer3• 14 years ago

I'm not sure I really get what you are trying to say. I know what a transaction is, and I know it wasn't the fault of transactions. It was the fault of our poor use of transactions, in the same monolithic transaction pattern that the OP appears to be advocating.

jeltz6• 14 years ago

Indeed, transactions should be as short as possible but no shorter. If your code crashing within a set of queries would leave the code in an inconsistent state you should probably wrap them in a transaction, but if not you should not put them in the same transaction.

zzzeek4• 14 years ago

> An example of this going wrong in production, I work in the online gaming (gambling) industry. One of our users won a large jackpot, our code started a transaction, contacted the 3rd party to have them release the funds, recorded the win in the transaction journal, updated the customers balance etc. Then the stored procedure which inserted a row into the outgoing email queue had a small error. This caused all of the database work on our end to rollback.

Updating a customer's winnings and recording a win are definitely things that should be together in a transaction - if one happened and not the other, that's a failure.

This is not the fault of using a transaction, this is the fault of not working with what is essentially a distributed transaction. Since you are relying on a message against a third party, you need to build distribution into this system, which is challenging. You might contact the third party after you've completed the internal processing, and you might use two-phase semantics even such that you can "PREPARE TRANSACTION" the work you've done locally, (nearly) guaranteeing that a commit will proceed, then work with your external messaging, then commit locally.

background at http://en.wikipedia.org/wiki/Two-phase_commit_protocol

VBprogrammer3• 14 years ago

> Updating a customer's winnings and recording a win are definitely things that should be together in a transaction - if one happened and not the other, that's a failure.

Yes, they these clearly do belong in the same transaction. Inserting a congratulations email into the email queue doesn't.

eevee20• 14 years ago

It's only default behavior. The alternative is for any request that runs more than one query to be inherently but unpredictably unreliable; that is definitely not acceptable.

If you're doing something complicated, you're going to have to tread carefully anyway. No default could have handled your situation cleanly.

For what it's worth, zope transactions (which Pyramid uses) support combining notions of "transaction" from arbitrary other services and tries to do the right thing for a commit and rollback. I've used this to keep a database and mogilefs in sync, for example.

tantalor2• 14 years ago

> Some have helpers for creating RESTful routes

Can somebody point to an example of this?

optymizer3• 14 years ago

Personally, I _like_ PHP because, at the core, it is a collection of utility functions to write webapps quickly. Here's a small set of those function that I would like to see somewhere else (like in Python for example):

Save a file: file_put_contents()

Load a file: file_get_contents()

Trim whitespace: trim()

Print a string (even numbers!): print $str

Dump an array: print_r()

Print the stack trace: print $e->getTraceAsString()

Want to embed HTML? Go ahead, _without_ any of this nonsense: print "<table><tbody><tr><td>"+str(val)+"</td></tr></tbody></table>"

Want to check for errors and improve the quality of the code? Go ahead! Use lower level functions like fwrite, fread, etc; most functions return FALSE on error, use try/catch, throw Exceptions, create custom Exception classes, go nuts with over-architecting if that's your thing.

Also, as someone who knows C and C++ rather well, I find PHP completely intuitive, very easy and flexible, as opposed to:

  if __main__=="__main__": 
      main()

and passing self around is just plain redundant.

The icing on the cake is that a huge part of the built-in functions wrap and extend existing C functions: strpos, strlen, so the language rarely gets in your way. The docs are pretty good (there's room for improvement).

So you can be a zealot all you want, but the truth is: the language doesn't make your code reliable - YOU make the code reliable and, from my experience, people who bash a language rarely know what they're talking about and it usually just boils down to personal preferences like braces vs no-braces.

Lastly, I wish you all the best in your fanatic bashing of a good tool that has proven itself appropriate for web applications. Everyone's tired of the following example, but I'm going to say it anyway: Facebook (and thousands of other large websites). Feel free to be in denial about that.

egonschiele2• 14 years ago

In Ruby:

    # Save a file
    f.write(str)

    # Read a file
    f.read

    # Trim whitespace
    " foo ".strip

    # Print anything
    puts 1 # even numbers!
    puts File.open("foo", "w+") # even file handles!
    puts [1, 2, 3, 4] # even arrays!
    puts [].class # even classes!
    puts [].method(:size) # even functions!

    # Dump an array (see above)

Python is similarly clear:

    # Save a file
    f.write(str)

    # Read a file
    f.read()

    # Trim whitespace
    " foo ".strip()

    # Print anything
    print 1 # even numbers!
    print open("foo", "w+") # even file handles!
    print [1, 2, 3, 4] # even arrays!
    print [].__class__ # even classes!
    puts [].remove # even functions!

    # Dump an array (see above)

Ruby and Python are extremely well documented. They have great standard libraries which wrap existing C functions too...and wrap them in a consistent fashion. They are also the second and third most popular language on Github, respectively...which means tons of great libraries to solve almost any problem you can think of.

Ruby and Python are just as easy to use as PHP.

getsat2• 14 years ago

Not sure about the Python ones, but the Ruby read/write file examples aren't quite fully done/correct here:

  # Equivalent of file_put_contents() in PHP
  # This could also be used for appending if the correct mode is specified.
  File.open("filename", "w") { |f| f.write("some data") }

  # Equivalent of file_get_contents() in PHP
  some_var = File.read("filename")

irahul2• 14 years ago

> Personally, I _like_ PHP because, at the core, it is a collection of utility functions to write webapps quickly. Here's a small set of those function that I would like to see somewhere else (like in Python for example):

As another commenter has already posted, these are pretty trivial in Ruby and Python(and plenty of other languages).

> Want to check for errors and improve the quality of the code? Go ahead! Use lower level functions like fwrite, fread, etc;

fwrite/fread improve quality of code? As opposed to what?

> The icing on the cake is that a huge part of the built-in functions wrap and extend existing C functions: strpos, strlen, so the language rarely gets in your way.

I don't see how your conclusion follows from your premise. How does a language using strlen equate to not getting in my way?

> from my experience, people who bash a language rarely know what they're talking about and it usually just boils down to personal preferences like braces vs no-braces.

None of the languages are perfect. Though a lot of people bash languages without knowing their shit, it doesn't mean all criticism is invalid. PHP has warts - warts that go beyond personal preferences.

optymizer3• 14 years ago

> these are pretty trivial in Ruby and Python I wasn't arguing that they're difficult, I was saying they're quick, dirty functions you can use to get something up quickly (the RAD way).

> fwrite/fread improve quality of code? As opposed to what? as opposed to just using file_put_contents() and never checking for the number of bytes actually written. The point I was trying to make is that you could use quick, high level functions (like file_put_contents()) and then replace them with more low-level functions like fopen()/fwrite()/fclose() to have more fine-grained checking of errors (you could complain that the script failed to open the file when calling fopen() and then you could print the exact reason why, as opposed to just printing 'could not write to file' when using file_put_contents).

> How does a language using strlen equate to not getting in my way? I switch between languages pretty often and so keeping an active context for each language in my mind is rather difficult. I have to recall if it's len(), str.len(), str.length, str.length() and so on for every other type of task I need to deal with. If the language is really similar to C, it is more natural for me to use strlen() even if I have to come back to it after 6 months. That's what I meant by 'not getting in my way'.

> it doesn't mean all criticism is invalid. PHP has warts - warts that go beyond personal preferences.

I agree. No language is perfect, but why do you feel compelled to say 'PHP has warts [...] that go beyond personal preferences' without actually bringing evidence. It makes it sound like you're speaking purely out of hatred for PHP and I can't respect that.

eevee20• 14 years ago

I get the feeling you aren't very familiar with Python. Actually I'm hard-pressed to name a popular language in which writing a string to a file is particularly difficult.

You don't have to check for errors in Python; most functions raise exceptions on error, rather than letting your program continue with a known bad state.

The `if __name__ == "__main__":` pattern is a cute trick to distinguish a module from a file being run directly. It's not strictly necessary; just a nice habit. It's spiritually similar to the checks you have to do in PHP library files to make sure they're not being run directly.

You don't have to pass `self` around. You just list it as a parameter. There are design reasons for this, it's a tradeoff, blah blah. Think of it as the price you pay for getting to type 'def' instead of 'function'.

I'm not a C programmer, and I doubt many people writing web applications are, so how does wrapping C functions with C names help me? Are `'b' in 'abc'` and `len('foo')` that difficult to understand?

I like to think I've covered my reasons for disliking PHP well enough by now.

Okay. You're not the target audience of this article, then.

optymizer3• 14 years ago

> a cute trick allow me to disagree about the cuteness of that. there are ways to distinguish a module from an executable file. For example, 'main' could be a special function (like in C).

> you just list it as a parameter yes, that's what I wanted to say. the fact is, in other languages I don't have to list it as a parameter and I don't have to get used to it. Personally, I find it annoying (but I could live with it, like everyone else).

> how does wrapping C functions with C names help me forgive my forward reference, but I will argue that "you're not the target audience" for this language. I found that PHP works best if you're coming from a C background and you treat it as a C-based scripting language (and this is kind of what PHP claims to be). I've always suspected that people coming from other backgrounds are the ones who will dislike PHP the most (and it doesn't surprise me), but I also don't know why they seem so vocal about it. I, for one, don't post negative comments about Ruby/Python (unless I'm comparing PHP with them) because I acknowledge that other people with, say, LISP backgrounds will find those more intuitive and will make efficient use of the them.

Anyways, cheers.

salimmadjd• 14 years ago

Great article! For those of you who say how easy PHP is, it's because you don't remember the early days when you had to compile php to run on your box, only to watch it fail after an hour of compilation :) history aside, these are just tools. For many site, perhaps for majority of tasks, PHP might be the best tool for the job. Once you start doing more complex stuff that will require additional libraries and modules then you need to look into other languages.

I used servlets from very early days, just because I could never understand another man's perl code and I thought the architecture was better. However J2EE got so big and academic that took all the fun out of coding. I've recently started to do some stuff in python and the fun is back again. I love all the NLP libs that are available for python in addition to vast support and ease of coding. Not to mention, I like the python community more than ruby (rails really). It just seems like python guys come from a stronger CS background and are not some over-night rail guys who want to push their faith down your throat.

pimentel• 14 years ago

Should I really learn Pyramid instead of Django? I'm thinking about what would give me most value as a developer, one who already knows his python.

grey413• 14 years ago

It's a tradeoff. Django is a full-stack framework, which integrates lots of components such as templates, form generation, and an ORM. This means that you can get off the ground quicker, and that the community is all more or less on the same page. The downside is that if you want to do something that Django isn't good at (complicated database stuff, logic in templates, etc), you are in for a world of pain (reportedly). Overall, Django is a great default for making CMS-type sites, but can become a technical debt if your requirements outgrow it.

Pyramid, on the other hand, deliberately not a full stack framework, sacrificing ease-of-use for flexibility. It doesn't include any database opinions at all, can swap templating languages on a whim and wouldn't know a form if you hit it over the head with one. The upside is that it has first class core components, really well defined extension points, an unmatched routing system, and a few truly excellent plugins (I love you pyramid_tm). The downside, of course, is that you will own your entire stack, which means that A) there is more up-front work researching, designing, and developing your application's component stack and B) there's no central community guaranteed to be using the same stack as you. Overall, pyramid is suited for essentially any use case, so long as you put the work into it.

tldr: Django is (somewhat) inflexible but easy, Pyramid is flexible but more demanding. Both are excellent.

There are probably more jobs working with Django, if that's a consideration.

javajosh• 14 years ago

Google App Engine for Python. You don't have to configure your host, you get great tooling and documentation, and a very good community of users.

jpwagner• 14 years ago

Great overview.

jipipayo• 14 years ago

Its funny how Ruby hordes overwhelms this thread talking about ruby not python nor php :-D

I only know PHP. How do I write a Web application in Python?

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