Object oriented programming with ANSI-C (1993)

https://ritdml.rit.edu/bitstream/handle/1850/8544/ASchreinerBook1993.pdf?sequence=1

by xkarga00 • 13 years ago

79 54 13 years ago

ritdml.rit.edu

blacksqr• 13 years ago

I ran into this a while back. Worth knowing about I think. I'd like to see a compare-and-contrast with "Writing Bug-free C Code." (http://www.duckware.com/bugfreec/index.html)

deletes2• 13 years ago

I have read Object oriented programming with ANSI-C and implemented my own class system in C with inheritance and polymorphism.

Taking a look at Writing Bug-free C Code the chapter about class is really just an example how to use structs with pointers that don't expose the underlying implementation.

If you want to learn oop read the Oop with Ansi-C, where classes similar to c++ with certain limitations are possible. The book explains everything in detail with including source code[http://www.cs.rit.edu/~ats/books/ooc-14.01.03.tar.gz].

ExpiredLink• 13 years ago

This seems to be the horrible Schreiner book. IIRC, he tries to do OO in C by using a special pre-processor. Sorry, this approach has never been relevant.

pmelendez• 13 years ago

For page 33:

" struct Circle { const struct Point _; int rad; }; We let the derived structure start with a copy of the base structure that we are extending. Information hiding demands that we should never reach into the base structure directly; therefore, we use an almost invisible underscore as its name and we declare it to be constto ward off careless assignments. "

This looks so manual that reminds me "C with classes". It is a very pedagogic read though.

Roboprog3• 13 years ago

I had to make an application framework something like this with ANSI C in the 90s. Make a structure (or two) full of function pointers as an "interface", pass it (them) as the first parameter to all the relevant functions as "this"/"self". (wait, that kinda looks like what "Go" does - hmmmm)

Of course, some in the company tried to pad their resumes with actual (gahd-awwwful) C++. Lovely jewels like this:

    if ( output_format == A) {
        a.write_pg_header();
    } else {
        b.write_pg_header();
    }

Guess they never heard of a virtual method. Then there's the fun of all the memory leaks from copy constructors and other silly C++ pitfalls.

Simulated OOP in C is an interesting exercise. I suppose if I had not learned an OOP language other than C++ first, I would have thought C++ is just how (hard) it's supposed to be :-)

Roboprog3• 13 years ago

Also did an OOP emulation a few years earlier than this using Clipper 5, of all things. No structs, but you could make constants for array indices, and assign a closure/block to each array element, using the array as a virtual method table.

coldcode• 13 years ago

I did as well in 1988, but mine was missing a lot of things as I didn't have any good examples to base it on. All I had ever read was the Smalltalk issue of Byte.

filkatron• 13 years ago

Relative noob here, I'm learning programming in general and I picked C to start with. My university courses are pretty shitty so I have to do it by myself. OOP is pretty repulsive to me. I don't know why. Too many abstraction that I can't see clearly.

Would any of you recommend me to try and get the hang of OOP using C or should I just pick up Java or C++ ?

(sorry if this is a inappropriate comment on this post)

cypher543• 13 years ago

Unless you're working on ancient software or writing an OO programming language that translates to C, you really shouldn't need to worry about OOP in C. I suggest learning as much as you can about C and then graduate to C++. Java would be fine, too (as would C# or Python or whatever), but I personally like writing C++ whenever I can. It's a nice blend of low-level system programming and high-level abstractions. C++11 is even better with standard threads, clocks, promises, futures, anonymous functions, and so on.

UNIXgod2• 13 years ago

Consider a dynamic language to get a grounding on the abstaction. OOPS concepts make more sense in those especially if your doing windowing and graphics. May be worth it to look at smalltalk or ruby.

clarry• 13 years ago

Perhaps you could forget the buzzword and just learn to code well in your chosen language.

Then try another language -- preferrably one that is quite different from what you started with -- to learn a completely different approach.

wylee• 13 years ago

To just get the hang of OOP, you might be better off starting with Python or Ruby (or some other language with a REPL). Although you can do OOP style programming in C (and it's a fun exercise), there's a lot of low level stuff that's really interesting but not particularly relevant to the basic concepts of OOP.

If the choice is between just Java and C++, I'd go with Java, but it probably depends on what your long term goals are.

In any case, learning any language can't hurt, so I don't think there's any danger of making the wrong choice--unless you get so stuck that you're not making any progress. Just pick whatever "fits your brain" then branch out later.

dsego2• 13 years ago

You could try Objective-C. It's proper OOP with messages, and you can write normal C style stuff. None of C++ stupidity (like cout<<"Hello World", yuck).

pjmlp7• 13 years ago

Except Objective-C is Apple's toy.

GNUStep does not count, as it is ages behind Cocoa.

wsc981• 13 years ago

Perhaps the kinds of applications you've build don't lend themselves particulary well to OOP methodologies. Certainly OOP is very useful in most "business" apps.

stefantalpalaru• 13 years ago

Use GObject[1] from GLib.

[1] https://developer.gnome.org/gobject/stable/

dsego2• 13 years ago

Vala is a nice C#-like language based on gobject. It also has wrappers for most popular C libraries.

https://wiki.gnome.org/Projects/Vala/Tutorial

foobarian• 13 years ago

I would suggest Java. It has a really clean object model, is statically typed, and if you use Eclipse it will compile-as-you-write to highlight errors, suggest fixes, and autocomplete a lot of useful stuff like methods you can call on an object.

While you are at it, read "Effective Java" by Josh Bloch--it's full of excellent advice about OOP, and applies way beyond Java itself.

My biggest epiphany about OOP was realizing that just because you can use inheritance, you don't have to use it everywhere. You read a lot of toy examples where you have e.g. a shape, then you have children like square, rectangle, etc. and try to do everything this way in your projects. But it's actually often a really bad idea to overdo it, and Effective Java has some good explanations on the tradeoffs.

d4rti• 13 years ago

Zed Shaw's Learn C The Hard way has an exercise that builds a simple prototype based OO system using C[1].

[1] http://c.learncodethehardway.org/book/ex19.html

davidgerard• 13 years ago

Nice book, but please change the title to note this is a 221-page PDF!

mikevm• 13 years ago

When people tell me that they love C, I don't get it.

C is so tiny that if you're going to write anything non-trivial you either have to re-implement various common data-structures yourself, or find appropriate libraries. No built-in string type, no vectors, no nothing. Also, the lack of generics makes for really ugly code, filled with void pointers and casts whenever you attempt to write type agnostic data structures such as lists, queues, etc.

It also seems that whenever I have to write in C, I end up writing code that painfully wants to be object-oriented, or implementing features that are already part of C++.

So why would you willfully pick to use C when C++ is around? Heck, even if some sick reason you don't want to use explicitly use objects, at least you can enjoy some of the other benefits of C++ (e.g. its standard library).

georgemcbay• 13 years ago

"...or find appropriate libraries."

But... finding appropriate libraries is generally simple. Due to C++'s ongoing ABI issues C is, to this day, still the predominate language for library authors who want their library to be nearly universally consumable (in C, C++, Python, Go, Ruby, node/JavaScript, etc).

That said, I agree with part of your point which is why I use Go when I can today (though it also isn't suitable to be a C-like universal library language for other reasons). Built in strings, interfaces, maps, etc remove a lot of the basic code level pain points without also introducing the overbearing level of language complexity of C++/stl/boost (and I say that as someone who spent nearly 10 years programming professionally in C++ and at one time misguidedly considered myself a fan of the language).

Go is not so big on the full spectrum of traditional object orientation or generics, but once adapting to OO solely by composition and duck-type interfaces I haven't found either of those to be a big issue for me.

to3m• 13 years ago

I've found this too. It's rather turned me off using C for anything; in no time at all, I always find myself doing something that would be very straightforward in C++, but is a certain amount of bother in C. So (I ask myself)... what is this buying me again? What's the point?

Fortunately, most C++ compilers' support for inline C code is excellent. Even gcc didn't get it wrong ;)

icedchai• 13 years ago

People love C because it's simple.

Figuring out what some C++ code does can be very complex, depending on what particular features the previous developers decided to use.

C is also the lowest common denominator, making it better for certain development tasks (I'm thinking of mainly lower level shared libraries.)

pjmlp7• 13 years ago

I also don't get it.

When I got to learn C, back in 1992, I was already doing system programming in MS-DOS with Turbo Pascal.

A language with support for OOP, proper modules, blazing compile times, strings, vectors that don't decay into pointers, safer while offering the same low level features as C.

C looked stone age to me, luckily I got into C++ a few months later and saw a language which gave me back most of the features Turbo Pascal had, with the advantage of being a language in the process of being standardized.

I only used C when forced to do so during university assignments and on my first job.

Sadly C's compatibility is what helped C++ to become widespread, but also the cause of many of its issues in terms of security. At least with modern C++ is possible to avoid Cisms as much as possible.

maratc2• 13 years ago

Some people think that C is a better language than C++, and may disagree with you on standard library being a "benefit".

You may try to look at "C++ FQA" at http://yosefk.com/c++fqa/ for an example.

a8da6b0c91d• 13 years ago

If I recall correctly that FQA mostly bitches that C++ isn't Smalltalk, and offers no praise for C.

ketralnis• 13 years ago

And yet your operating system and over half of your userland is in C. Must be doing something right.

pjmlp7• 13 years ago

Only if you are speaking about UNIX distributions, excluding Mac OS X.

0x09• 13 years ago

C is so tiny that if you're going to write anything non-trivial you ...

pretty much know exactly how you're going to write it from the start. Since C is so constrained it's very easy to design for, and you usually have a very clear idea of what you are getting into, even if that includes reimplementing a common data structure or using external libraries. And if you are using an external library, the API is not likely to surprise you. There are countlessly fewer ways to design something within the rules of the language in C than C++. Different people will see this as a blessing or a curse.

For some situations it just makes sense. If your program revolves heavily around C libraries you will likely be forced into a C-like design anyway. And likewise, if you are designing a library with a primary interface in C. If you are already coding in this style, C offers some niceities to (ab)use that C++ doesn't (especially compound literals, designated initializers, and VLAs).

It's easy to become familiar with C which makes it easy for C to be a go-to language (obviously this depends on your problem space.)

EliRivers• 13 years ago

There are many platforms that have a C compiler, but not a C++ compiler. Sometimes you just don't have the choice.

mratzloff• 13 years ago

Well, C is simpler than C++. That means it's simpler to understand exactly what is happening. It's not that far removed from an assembly language.

And you really can't beat C for FFI. If you have a common library you want to share among many different platforms, C is the way to go.

aryastark• 13 years ago

So why would you willfully pick to use C when C++ is around?

There are many reasons to not use C. But C++ existing is not one of them. Over the 15 years or so that I've used C++, there is always the constant nagging feeling that I don't really know what is going on. My programs tend to work. But I often find that there are incredibly subtle nuances buried deep in the C++ run time model that are simply beyond comprehension.

If you can keep all the rules of C++ in your head, then you are a god among gods.

Today there are few reasons to even need C++. I tend to stick with C or go to Perl/Python. I don't really need a language that attempts to straddle the middle. Especially one that more often than not, gets it all wrong anyway.

EpicEng6• 13 years ago

    It also seems that whenever I have to write in C, I end up writing code that painfully wants to be object-oriented, or implementing features that are already part of C++.

So I guess you just don't really know/aren't comfortable with C. That's fine, but that hardly means that everyone else has the same problem.

    So why would you willfully pick to use C when C++ is around?

Because they are two very different languages and have their own strengths and weaknesses?

OO is not the "one true way", that has been shown time and time again. It's really not difficult to find a library for things you need in C. The fact that they aren't all available to include the moment you open your editor/IDE isn't a reason to use C++.

I use both C and C++ regularly. I love a lot of things about C++, but it also brings a lot of baggage along with it. It is an extremely complex language and I have seen some really, terribly awful code written in it.

I've seen bad C code as well, but C++ makes it easier to write bad code and harder to restructure it if you need to because you have to deal with much more abstraction. C++ also lends itself to writing code which contains very subtle errors in it. C makes that more difficult.

I read your post and I just hear someone with little C experience who loves his objects and can't fathom doing things another way.

klipt• 13 years ago

OO is not the "one true way"

Personally, I think C++'s big win over C++ is not OOP but generics. You can do OOP in C if you want; you can't do generics efficiently and safely.

fatca• 13 years ago

In what are these various common data-structures supposed to be implemented? Also in a language that already has them?

We have to keep building and maintaining a kernel, a libc, and other basic infrastructure software. Should we also do that in a language that implements the missing things already? Maybe the CPU itself should implement these common data structures?

What solution do you propose?

daviddlhg• 13 years ago

Historical interest: Amiga BOOPSI. Not saying it was perfect, but it certainly existed.

http://en.wikipedia.org/wiki/BOOPSI http://en.wikibooks.org/wiki/Aros/Developer/Docs/Libraries/I...

bluedino• 13 years ago

I was kind of expecting this to be a link to Zhivago's article on OOP with C

http://www.codersger.de/mags/cscene/CS1/CS1-02.html

ithinkso• 13 years ago

Big C/C++ fan here, although I'm sure writing software for PC in C is extremely painful. Personally for PC soft I'm using C++ (Qt) but I actually really had to learn some 'higher level' language for this particular job. However, my main area of interest are microcontrollers and there is NO other option than learning C (C++ compilers costs too much for a hobby projects).

Object oriented programming with ANSI-C (1993)

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