CODEWITHSUNDEEP
cprogramming-languages
Sauce McBoss
Sauce McBoss

Reputation: 6937

Include libraries in other languages in a C application

My general question is this: what's the most common way to include libraries in other languages in a C application?

For example, if I have a Ruby library intended for doing function X, and a Python library for doing function Y, how can I write a program in C (the language, that is) that uses the functions in each?

I've seen wrappers that give access to C libraries in these higher languages, but are there wrappers that go the other way? Is there a common way of handling this in general?

Upvotes: 0

Views: 487

Answers (1)

uliwitness
uliwitness

Reputation: 8773

Are these native-code libraries (i.e. have they been compiled?) Or are these source libraries (i.e. a bunch of text files containing Ruby source code)?

If the former, libraries in a language like Ruby or Lua or so usually have a published binary interface ("ABI"). This is low-level documentation that describes how their libraries and its functions work under the hood. Often, those are defined in C or C++, or whatever language was used to implement the interpreter/compiler for Ruby itself.

So you'd have to find that documentation, and find out how to call the parts you are interested in. Some languages even use the same ABI as C does, and you just need to create a header file that matches the contents of the library and you can call it directly (This is how you integrate e.g. assembler and C, or even C++, which you can get to generate straight C functions).

If the latter, you usually need to find an embeddable version of the language, and find out how to run a script from inside your application (This is how Lua is usually used, for example).

But are you sure you need the given Ruby libraries? Often, common libraries are implemented using a C or C++ library under the hood, and then just wrapped for scripting languages, so you can just skip the scripting translation layer and use the (maybe slightly more low-level) library yourself.

PS - there are also automatic wrapper generators, like SWIG, that will read a file in one language and write the translation code for you.

Upvotes: 1

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