how to write a wrapper?
most of the Euphoria "heavyweights" (as opposed to the "lightweights", like me)
devote much of their time and effort into wrapping libraries to extend Eu's
functionality. I understand the basic mechanics of this:
There are actually 3 steps to go through.
1/ Your wrapper must open a shared file (.dll on Windows, .so on Linux/BSD)
using open_dll() (be sure to include machine.e). This function will return
some atom I'll call entry_point.
2/ For each routine you need to wrap, define a constant representing that
routine using defie_c_func (or _proc):
constant
the_func=define_c_func(entry_point,func_name,arg_type_list,return_type)
You can also access public variables using define_c_var().
3/ Then, in any program using the routines, including your own wrapper,
you use c_func() or c_proc() to call the routine, using the identifiers
defined in stage 2 as routine ids.
And that should be all, unless you have to fiddle with calling convention.
If the doc for your dll talks about cdecl, then there is a specific syntax
to use in define_c_func.
(thanks to CChris for this post). I'd like to have a go at writing a simple
wrapper but am unsure where to start. I assume I don't need much knowledge of C,
but surely I need some? and if so, what, particularly? I don't (hopefully) need
spoon-feeding, but if someone could point me in the right direction, that would
be great. I'm sure there are many other Eu coders who would like to see a
tutorial on this subject. I'd be happy to write one myself, once I've learned the
basics.
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