Re: Python C API vs Ruby C API

	Subject: Python C API vs Ruby C API
	Date: mer 20 feb 13 11:57:22 +0900

Quoting Patrick ([e-mail]):

> The Ruby C API looks lighter but much easier to work with.

Once you get the hang, it is very straightforward. I do not know
Python, but compared with JNI, Ruby's way of interacting with C code
is a pleasure to work with.

> Is VALUE the only type?

Ruby being a pure OO language, everything is an object, and thus only
one type needs to travel through the border. But once you have a
VALUE, you can potentially access the whole object (i.e. call all of
its methods) from the C world. For those classes that are most often
used (numbers, strings, arrays and hashes, to name a few), there are
helping functions. You need to learn them, but once you learned them,
things work well. If you look at Ruby's source code, you will find
tons of examples. Under /ext you will find all those libraries that
are shipped with Ruby and which have C code. 

> Is it true that I do not have to manually increment and decrement
> values as well?

If you mean reference counts, the only cases when some complexity
appears is when you pass VALUEs to C and you want to use them after
the method call has returned (in background threads, for
example). Otherwise, the objects you create from C are correctly
garbage-collected. When you create you own Ruby classes in C, you
assign to them a C structure, which is allocated for each instance at
object creation, and which you can access from C-code methods. There
you can safely store all C stuff that you will need along the life of
the object. You must provide a function where your stuff is freed,
which is called when the object is GCed.

> I was also wondering about extending Ruby. If I create a C module
> FOO and another module POO, can FOO call functions from POO or is
> there a way to make them visible? I might like to call TK from
> another C module

The classes and modules you create from C become full-fledged Ruby
classes and modules. You can add C methods to classes you define under
Ruby, and vice-versa. 

I suggest that you download the Ruby source. Inside the directory you
will find a file called

README.EXT

which has much information about this topic. I personally needed a
good chunk of time and effort to make sense of that, but it has not
been wasted time.

Carlo

-- 
  *         Se la Strada e la sua Virtu' non fossero state messe da parte,
* K * Carlo E. Prelz - [e-mail]             che bisogno ci sarebbe
  *               di parlare tanto di amore e di rettitudine? (Chuang-Tzu)