info bigloo

28.8 A complete library example

For the means of an example let’s suppose we want to design a Bigloo library for 2d points. That library is made of three implementation files: two C files, cpoint.h and cpoint.c and one Scheme file spoint.scm. Here are defined the three files:

cpoint.h:

struct point_2d {
   double x, y;
};

cpoint.c:

#include <stdio.h>
#include "cpoint.h"

int print_point_2d( struct point_2d *pt ) {
   printf( "<point-2d: %g, %g>", pt->x, pt->y );
}

spoint.scm:

(module __point
   (include "spoint.sch")
   (extern  (include "cpoint.h"))
   (export  (make-point::s-point_2d* ::double ::double)
            (print-point ::s-point_2d*)
            (point? ::obj)))

(define (make-point::s-point_2d* x::double y::double)
   (s-point_2d* x y))

(define (print-point p::s-point_2d*)
   (print_point_2d p))

(define (point? obj::obj)
   (s-point_2d*? obj)
   obj)

makelib.scm:

We want our library to be composed of the whole exported Scheme functions. Thus the file to build the heap library could look like:

(module __point_makelib
   (import __point)
   (eval (export-all)))

point.init: Let’s suppose that the point library requires the libposix library. This means that any file linked with the point library needs to be also linked with the posix library. Furthermore, programs making use of the point library needs to include the point.sch file. That Scheme file needs in turn the C file point.h otherwise the produced C files won’t compile. The need for the libposix library and for the point.h file may be specified inside the point.init file. For our current library, the point.init file could look like:

(declare-library! 'point 
                  :basename "point" 
                  :srfi '(point)
                  :eval-init '__point_makelib)

(set! *ld-options*
      (string-append "-L/usr/lib " *ld-options*))

(set! *bigloo-user-lib*
      (cons "-lm" *bigloo-user-lib*))

(set! *additional-include-foreign*
      (cons "cpoint.h" *additional-include-foreign*))
      
(define-macro (point x y)
   `(make-point ,x ,y))

This file updates some compilation variables (*ld-options*, *bigloo-user-lib*, *additional-include-foreign*) and defines a macro: point. Because the point.init file will be loaded each time a compilation require the point library is spawned, user code are allowed to use the point macro. Here is an example file making use of the point library:

example.scm

(module example)

(let ((p (point 2.9 3.5)))
   (print "point?: " (point? p))
   (print "point?: " (point? 4))
   (print-point p)
   (print "done..."))

To conclude that example here is the Makefile used to compile the point library, heap file and one example.

# bigloo flags
BIGLOO          = bigloo
RELEASE		= ‘$(BIGLOO) -eval ’(begin (print *bigloo-version*) (exit 0))’‘
BHEAPFLAGS      = -unsafe -q -mkaddheap -mkaddlib -v2 -heap-library point
BCOMMONFLAGGS   = -mkaddlib -fsharing -q $(VERBOSE)        \
                  -copt ’$(CCOMMONFLAGS)’ -cc $(CC)
BSAFEFLAGS      = $(BCOMMONFLAGGS) -cg -O3 -g -cg -unsafev \
                  -eval ’(set! *indent* 4)’ -rm
BUNSAFEFLAGS    = $(BCOMMONFLAGS) -O4 -unsafe

# cigloo flags
CIGLOO          = cigloo

# cflags
CC              = gcc
CCOMMONFLAGS    = -I.
CSAFEFLAGS      = $(CCOMMONFLAGS)
CUNSAFEFLAGS    = $(CCOMMONFLAGS) -O2

# library objects
SAFE_OBJECT     = olib/spoint.o olib/cpoint.o
UNSAFE_OBJECT   = olib_u/spoint.o olib_u/cpoint.o

all: .afile heap lib example

.afile: spoint.scm makelib.scm
	bglafile $^ > $@

heap: point.heap

point.heap: spoint.sch spoint.scm
	$(BIGLOO) $(BHEAPFLAGS) makelib.scm -addheap point.heap

lib: lib_u lib.a

lib.a: olib $(SAFE_OBJECT)
	ar qcv libpoint_s-$(RELEASE).a $(SAFE_OBJECT) 

lib_u: olib_u $(UNSAFE_OBJECT)
	ar qcv libpoint_u-$(RELEASE).a $(UNSAFE_OBJECT) 

olib:
	mkdir olib

olib_u:
	mkdir olib_u

olib_u/spoint.o olib/spoint.o: spoint.scm
	$(BIGLOO) $(BSAFEFLAGS) $(<F) -o $*.o -c

olib_u/cpoint.o olib/cpoint.o: cpoint.c
	$(CC) $(CSAFEFLAGS) $(<F) -o $*.o -c

spoint.sch: cpoint.h cpoint.c
	cigloo $^ > $@

example: heap lib
	$(BIGLOO) -v2 -L . -library point \
            -static-bigloo example.scm -o example

clean:
	-/bin/rm -f point.heap
	-/bin/rm -f spoint.sch spoint.c
	-/bin/rm -fr olib olib_u
	-/bin/rm -f example example.c example.o
	-/bin/rm -f libpoint_s-$(RELEASE).a libpoint_u-$(RELEASE).a

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