Friday, April 11, 2008

Which Languages Handle Packages and Libraries Best?

In the post Why Do We Use C++, I made the following statement.

Another, often forgotten strength of C++ and of many traditional modular and modular-turned-OO languages is linking, or more generally, we might say 'package management'. C++ innately offers build-time linking and runtime 'linking' is also usually available (i.e., DLLs). This allows graceful scaling. Tool support for this in C++ is strong and reasonably robust because C++ is so frequently used to build enormous projects. It's possible to build massive projects in pieces in ways that are awkward or impossible in many functional or logic languages.

Simon wrote,

C++ good at linking and package management??? That's the most ridiculous thing I've heard all week. This is one of the weakest aspects of C++. Where to start:
* no standard ABI for compiled code. ("Don't mix compilers")
* no standard for managing namespaces and packages like in Java.
* Very hard to evolve a class and keep binary compatibility. Lots of obscure compiler depend rules need to be followed to do this. ("Change a .h file, rebuild everything that uses it")
* dynamically loading code modules has to be done manually. Java, Python and other languages load classes on demand.
* C++ code can call C code, but any other kind of mixed language development is a nightmare.
* easy to break features like dynamic_cast when loading share libraries. (My fun debugging adventure this last week...)

I think Simon makes some excellent points here. So I'd like to ask the community.

What is the best language (and what are the best language features) for linking/loading and package and library management?

5 comments:

michaelw said...

I always liked ML's Functors (see, e.g., Designing a Generic Graph Library using ML Functors), however, I haven't done anything with it that really stretches it to the limits.

Tom Finnigan said...

My company is in the process of taking a c++ codebase and making it available as a library. c++ does have some serious issues when being used as a library, since iostream implementations are generally not binary compatible, and the runtime compiled against matters in other various ways.

Some of our library users have suggested providing C bindings, because it would alleviate a lot of the problems.

Other than C, languages that are interpreted all seem to do pretty well. But if you give the c++ source, you can also get very good compatibility, so that's not really apples to apples. Java has paid a lot of attention to the problem, and do well.

The best I've seen is a dependency resolution system such as perl's CPAN. This isn't a language feature per se, but greatly enhances the usability of libraries, even the compiled modules.

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Anonymous said...

C#. (<-- period)

You don't ever have to think about moving things out in separate dlls, and it's very easy to add links to e.g. c-dlls.

And via reflection you can access any dll you'd like. It's heaven ;)

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