Hot Reloading in Swift

https://www.merowing.info/hot-reloading-in-swift/

by mgrayson • 4 years ago

99 34 4 years ago

markhelo• 4 years ago

"Microsoft has been killing it over the last decade regarding dev tooling and experience, so it is not a big surprise."

To be fair, for all the flack Microsoft got/gets, the dev tooling for Windows ecosystem is miles ahead of anyone else and world class. Perhaps I am biased as I worked there at one point, but since I don't anymore, I have also seen tooling from Apple and Google and they are a couple of decades behind. There is some truth to why Steve Ballmer went ballistic with his Developer chant, they really built great tooling for developers.

game-of-throws• 4 years ago

MS had "edit and continue" (aka hot reloading) in Visual Basic in the 90s. Then I switched to other languages and I've gone without it the rest of my career. I don't think VB the language is very good, but the developer experience still beats anything I've used since then.

pjmlp3• 4 years ago

With the caveat that Borland is even better before they decided to focus on enterprise customers, and went through all those acquisitions and name changes.

Delphi and C++ Builder are still unmatched in many capabilities on the Visual Studio side.

refulgentis2• 4 years ago

This is an odd response given the article calls at Google as having the gold standard for this, and I'm not sure there's any equivalent at all at MS? They push Flutter too

jayd16• 4 years ago

You mean like this?

https://docs.microsoft.com/en-us/visualstudio/debugger/hot-r...

"Microsoft has been killing it over the last decade regarding dev tooling and experience" was a direct quote from the article.

m_at_goog• 4 years ago

Maybe they mean internal at Google? Internal Google tooling is pretty hit or miss, especially with older products that are a patch work of different internal only Google stacks.

pjmlp3• 4 years ago

The gold standard are Smalltalk and Common Lisp environments, that people pushing Flutter tend to ignore on their marketing, as they ignored the existing work on Java and .NET ecosystems.

tester756• 4 years ago

There's emoji after "killing it"

I believe it changes meaning of this sentence.

frosted-flakes• 4 years ago

No it doesn't? In that context, "killing it" means doing a great job.

can16358p• 4 years ago

Agreed. Visual Studio is an excellent piece of software, along with .NET and C#.

I think Apple isn't that bad either, yet still behind MS.

Google is a disaster though. A few weeks ago I needed to download Android Studio. Downloaded a clean stable release from its official site for my machine (M1 Mac). From that clean install literally erroring while trying to launch AVDs to cryptic error messages about JDK environments, Google's the only IDE out of these big three where I get countless of errors and losing hours on something that literally doesn't work out of the box.

Hope Xcode and VS never becomes something crappy like Android Studio.

musesum3• 4 years ago

Ironically, I think Brad Cox had something like this in mind, after coming up with Objective C. Or at least, pluggable components [1]

I wonder what the threat model would be? Injectable binaries seem like a decent attack vector. But, if we're talking 2040, maybe a signable Merkle tree would do the trick.

Meanwhile, have been experimenting with recompiling Metal code at runtime. Was kinda fun with ObjC/C++/OpenGL, a few years ago.

[1] https://thenewstack.io/objective-cs-roots-in-the-life-of-bra...

dmix• 4 years ago

Erlang has had hotloading for a long time and seems to be fine security wise AFAIK.

kaba0• 4 years ago

Hot reloading’s quality (and to a degree, security) depends mostly on how fine-grained a change can be. The reason Lisp-REPl workloads are so well loved is that very small scopes can be changed easily, Erlang also has a sane encapsulation that can be swapped without much fuss.

melony• 4 years ago

Most of (traditional) Erlang deploymens are in embedded systems. They have a different threat model.

toast0• 4 years ago

Erlang has a very limited security model. In the default distribution, any process on any node can spawn a process on any other connected node to run any function --- you can send the function too. Modules can have a function to run on load, too. Loading an untrusted module is asking for that module to take over your whole system. Best to make sure nobody unauthorized can do that.

astrange• 4 years ago

Objective-C used to support reloading but now explicitly does not (dlclose() doesn't do anything) because it's unsafe.

Xcode used to have these features (called Zero Link and fix and continue) but they were quickly removed because nobody used them.

saagarjha4• 4 years ago

Hot reloading is typically considered to be concept of swapping out an implementation rather than literally unloading the code from memory. Objective-C is mildly limited by its C heritage but one can go pretty far with runtime trickery to get a similar effect. The other features were removed because they were not fully fleshed out and too unreliable to use.

andrekandre• 4 years ago

  > quickly removed because nobody used them

what is the definition of "nobody"?

n=1 and all that, but as a developer i used it all the time and was totally dismayed it was removed...

KerrAvon• 4 years ago

If you read the first edition of his book[1], it's pretty clear about what he was trying for, which IIRC was essentially resumable software components as black boxes that you could buy off the shelf and integrate in your own products.

I find this quote interesting:

But in addition, “I had just become incredibly annoyed with proprietary languages,” he said. Fortran vendors, for instance, would add extra features to try to lock customers into their particular version.

But this is exactly what he did with Objective-C -- it was a proprietary language until NeXT bought his company! It could have had widespread adoption had there been a widely available implementation.

[1] https://archive.org/details/objectorientedpr00coxb

ChrisMarshallNY• 4 years ago

resumable software components as black boxes that you could buy off the shelf and integrate in your own products.

Wasn't that one of the goals of CORBA? [D]COM?

I know it was one of the lynchpins of OpenDoc, but that took it even farther, with a document-centric approach to applications.

saagarjha4• 4 years ago

Hot reloading is a user(/developer) facing tool. You open up the application and put some of your own code in it. Platform vendors have almost universally rejected this model because it takes away control from them, but just like all apps load system libraries because they’re signed and trusted the solution here is to allow the hot reloader to add their own root of trust along with the one in the OS. Then you can just sign your own interpositions and load them safely.

lisper2• 4 years ago

This is one of the main reasons I like Common Lisp, and Clozure CL in particular, which has a blazing fast compiler: my debug cycles are measured in seconds. Over dozens or hundreds of cycles it really adds up.

Cthulhu_• 4 years ago

Isn't lisp a scripting language though? Different flavor of language.

I mean JS used to be a scripting language, but thanks to Reasons there's a lot more involved to get fast development cycles.

lisper2• 4 years ago

Isn't lisp a scripting language though?

No. Where did you get that idea?

leecommamichael• 4 years ago

You can hot-reload any language that can load a dynamic library. Compile the hot-reloadable portion of your app to a dylib and use a hotkey to reload the lib.

mananaysiempre• 4 years ago

That is only the beginning, isn’t it? The hard part is figuring out how to migrate state, and clearly saying “no” when that fails instead of leaving the user to debug a configuration that could not have arisen had the new code been started from a clean slate. (I don’t think that’s actually possible to disprove, even, but at the very least guaranteeing that memory contains the types the new code thinks it does would be good.)

Hot Reloading in Swift

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