load_foreign_resource/1 [hookable]load_foreign_resource(:Resource)
Load the foreign resource Resource into Prolog. Relies on the
hook predicates foreign_resource/2 and foreign/[2,3].
The foreign resource to be loaded. The file extension can be omitted.
load_foreign_resource/1 takes a foreign resource and loads it
into Prolog.
The extension can be omitted from the filename given in the Resource argument.
Uses the foreign/[2,3] and foreign_resource/2 facts defined by the
user to make the connection between a Prolog procedure and the foreign
function. In this context,
the resource name is derived from Resource
name by deleting any leading path and extension
from the absolute file name of Resource.
When loading the foreign resource, it looks for a
foreign_resource/2 fact for the resource name. For each symbol
in that fact, it looks for a foreign/[2,3] fact that gives the name
of the Prolog procedure associated with the foreign symbol and the
argument specification.
Contrary to most hook predicates which reside in the user
module, load_foreign_resource/1 will look for
foreign_resource/2 and foreign/[2,3] facts defined in its source
module.
Foreign resources are created with the splfr tool (see The Foreign Resource Linker).
Errors in the specification of foreign/[2,3] and
foreign_resource/2 will all be reported when
load_foreign_resource/1 is called.
library(codesio) contains a foreign resource consisting of
three foreign functions, one init function, and one deinit function.
The Prolog source file contains the following lines of code:
:- dynamic foreign/2, foreign_resource/2.
foreign(codes_to_stream, '$codes_to_stream'(+codes,-address('SP_stream'))).
foreign(open_buf_stream, '$open_buf_stream'(-address('SP_stream'))).
foreign(stream_to_codes, '$stream_to_codes'(+address('SP_stream'),-term,-term)).
foreign_resource(codesio, [
init(codesio_init),
deinit(codesio_deinit),
codes_to_stream,
open_buf_stream,
stream_to_codes
]).
:- load_foreign_resource(library(system(codesio))).
Note that the foreign declarations are needed by other operations as well and should not be abolished after loading the foreign resource.
unload_foreign_resource/1,
foreign_resource/2,
foreign/[2,3],
Foreign Resources,
Calling C from Prolog.