Henry Vermaak wrote:
I'm not sure what you mean - do you mean would I be willing to write the
support myself?
i think he's asking what the use of it is. number 2 under the link he
gave.
Oh, ok. Well, I'll try to summarize:
Class constants add the ability to provide scoped, "namespaced" constants.
Although one can handle basic scoping with global constants, by placing them
in interface vs implementation, they were not designed to be scope-limited.
They also do not provide a way to group several constants under a common
name, though one can simulate this functionality using creative constant
names.
Some of the benefits of class constants are: 1. They provide object-oriented
constants, 2. They simplify coding by saving the developer from having to
write long constant names to distinguish global constants from each other.
3. They reduce coding errors due to the ability to only make public what is
necessary, keeping what is visible to outside units/classes to a mimimum.
I'm sure that there are other benefits, I just can't think of them off the
top of my head.
Personally, the main reason I need them is for compatibility. I have a large
Delphi codebase that I'm porting to FPC and it uses class constants all over
the code.
Here is an example of their use:
-- Start of Unit1.pas --
unit Unit1;
interface
type
TTest = class
private
const PrivateConst = '1';
public
const PublicConst = '1';
constructor Create;
end;
implementation
constructor TTest.Create;
var
Str: String;
begin
Str := PrivateConst;
Str := PublicConst;
end;
end.
-- End of Unit1.pas --
-- Start of Unit2.pas --
unit Unit2;
interface
type
TTest2 = class
constructor Create;
end;
implementation
uses
Unit1;
constructor TTest.Create;
var
Str: String;
begin
Str := TTest.PrivateConst; // Will cause compiler error because
PrivateConst is not visible to this class.
Str := TTest.PublicConst;
end;
end.
-- End of Unit2.pas --
Jon
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