Now, suppose your C/C++ program needs a library, in Unix
called /usr/lib/libfoo.so or /usr/lib/libfoo.a.
To use it we first create the file
config/foo.fpc
which looks like this:
///////////////////////////////
provides_dlib: -lfoo
provides_slib: -lfoo
///////////////////////////////
The file should be put in the 'config' directory used by
the Felix installation.
Now in you code you can write:
////////////////////////////////////////////
#import <flx.flxh>
body "#define main PROXY_MAIN";
proc main: int * &(charp) = "exit(main($1,$2));";
main(System::argc, System::_argv);
requires package "foo";
requires body '#include "foo.h"';
body cr"""
#include <stdio.h>
int main(int argc, char *argv[])
{
printf("Hello World argc=%d, argv[1]=%s\n",
argc, argc>1?argv[1]:"None"
);
foo();
return 42;
}
""";
/////////////////////////////////////////////
The requires package clause creates a dependency on
foo.fpc which in turn causes the right linker switches
to be use to link in the library automatically.
The requires body clause causes the header file
to be included, so that the call foo() in your code
binds to a declared function.
We COULD have put the #include directly in the body,
but we chose not to here.
ISSUE: wouldn't it be good not to have to do the
#include separately?
It is possible to do this:
body foo_h = 'include "foo.h"';
body foo_p = requires package "foo";
body foo = foo_h, foo_p;
requires foo;
but the question is: why isn't the header file
provided by the fpc package??
Should I change it? At present flxg doesn't have
to read and parse fpc files. We could make it do so.
I do NOT like this, because the files should be 'platform
independent'. At present, Felix generated C++ will compile
and run on any platform (modulo one platform dependent
include file).
OR we could do this:
#include foo // foo is a MACRO
and then make the C++ compiler have the switch
-Dfoo="\"foo.h\""
(although that is super ugly if the command line is
itself quoted .. :)
In that case, flx script can call flx_pkgconfig to retrieve
the requisite information. Another trick would be to simply
prepend some text to the front of files.
--
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net
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