How to use generics: what changed

Revision 0 to 1. Removed lines have a minus sign; added lines have a plus sign.

Title: How to use generics

New		Line
1	+	An example of how to use generics to write a `function gmax()` that takes the maximum of two not-yet-typed [[Variable\|variables]]. Note that while the functions here are namespaced by the classname, FPC versions from 3.1.1 onwards also support fully free-standing generic methods.
2	+
3	+	``` pascal
4	+	program UseGenerics;
5	+
6	+	{$mode objfpc}{$H+}
7	+
8	+	type
9	+	generic TFakeClass<_GT> = class
10	+	class function gmax(a,b: _GT):_GT;
11	+	end;
12	+
13	+	TFakeClassInt = specialize TFakeClass<integer>;
14	+	TFakeClassDouble = specialize TFakeClass<double>;
15	+
16	+	class function TFakeClass.gmax(a,b: _GT):_GT;
17	+	begin
18	+	if a > b then
19	+	result := a
20	+	else
21	+	result := b;
22	+	end;
23	+
24	+	begin
25	+	// show max of two integers
26	+	writeln( 'Integer GMax:', TFakeClassInt.gmax( 23, 56 ) );
27	+	// show max of two doubles
28	+	writeln( 'Double GMax:', TFakeClassDouble.gmax( 23.89, 56.5) );
29	+	readln();
30	+	end.
31	+	```
32	+
33	+	---
34	+	From the Free Pascal wiki, page "How to use generics", as it stood on 2023-09-20 after a change by RogueScholar, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).