Logtalk 2.25.0 files.

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1288 b08c6af1-5177-4d33-ba66-4b1c6b8b522a

Logtalk/examples/aliases/NOTES

@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.24.0
+Release 2.25.0
 
 Copyright (c) 1998-2005 Paulo Moura.  All Rights Reserved.
 =================================================================
@@ -10,4 +10,4 @@ To load this example and for sample queries, please see the SCRIPT
 file.
 
 For a description of this example, please see the comments in the 
-aliases.mlgt metafile.
+aliases.lgt source file.

Logtalk/examples/aliases/SCRIPT

@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.24.0
+Release 2.25.0
 
 Copyright (c) 1998-2005 Paulo Moura.  All Rights Reserved.
 =================================================================
@@ -30,6 +30,23 @@ yes
 Side = 2 
 yes
 
+| ?- square(2)::predicate_property(side(_), Property).
+
+Property = public ;
+Property = static ;
+Property = declared_in(rectangle(_G264, _G265)) ;
+Property = defined_in(rectangle(_G297, _G298)) ;
+Property = alias(width(_G182))
+yes
+
+| ?- square(2)::predicate_property(width(_), Property).
+
+Property = public ;
+Property = static ;
+Property = declared_in(rectangle(_G262, _G263)) ;
+Property = defined_in(rectangle(_G293, _G294))
+yes
+
 
 % check the object circle(_) public protocol:
 

Logtalk/examples/aliases/aliases.lgt

@@ -0,0 +1,70 @@
+/*
+This example illustrates the use of the predicate directive alias/3 for 
+defining alternative names for inherited predicates.
+*/
+
+
+% first, we define a simple parametric object for representing rectangles:
+
+:- object(rectangle(_Width, _Height)).
+
+	:- public(width/1).
+	:- public(height/1).
+	:- public(area/1).
+
+	width(Width) :-
+		parameter(1, Width).
+
+	height(Height) :-
+		parameter(2, Height).
+
+	area(Area) :-
+		::width(Width),
+		::height(Height),
+		Area is Width*Height.
+
+:- end_object.
+
+
+% next, we define a square object which adds an alias, side/1, for the 
+% inherited predicate width/1:
+
+:- object(square(Side),
+	extends(rectangle(Side, Side))).
+
+	:- alias(rectangle(_, _), width/1, side/1).
+
+:- end_object.
+
+
+% a similar example can be defined using ellipses and circles:
+
+:- object(ellipse(_RX, _RY)).
+
+	:- public(rx/1).
+	:- public(ry/1).
+	:- public(area/1).
+
+	rx(Rx) :-
+		parameter(1, Rx).
+
+	ry(Ry) :-
+		parameter(2, Ry).
+
+	area(Area) :-
+		::rx(Rx),
+		::ry(Ry),
+		Area is Rx*Ry*3.1415927.
+
+:- end_object.
+
+
+% in this case, we define an alias named r/1 for the inherited 
+% predicate rx/1:
+
+:- object(circle(Radius),
+	extends(ellipse(Radius, Radius))).
+
+	:- alias(ellipse(_, _), rx/1, r/1).
+
+:- end_object.