[fpc-pascal] class property accessor static

[Maciej Izak]

2017-02-07 12:10 GMT+01:00 Mattias Gaertner <nc-gaertnma at netcologne.de>:

> The getter/setter of a class-property must be "static" (Delphi
> compatible).
> If I understand "static" correctly, then "static" simply omits passing
> the class as parameter. So a static class procedure is just a dumber
> version of a normal class procedure.
>
> What is the advantage of using "static" for class property accessors?
> Aka: Why did Delphi choose static here?
>

Generally "static" means no hidden parameter "self". "static" for methods
is used for methods designed for callbacks from external API.

We have 3 possibilities:

===code begin===
type
  TFooClass = class of TFoo;
  TFoo = class
    function A: Int32; // self as instance
    class function B: Int32; // self as meta class of TFoo
    class function C: Int32; static; // no self

    property D: Int32 read A;
    property E: Int32 read B;
    class property F: Int32 read C;
===code end===

"class property" has two advantages. First: you can use "static" methods
for properties and second: will work for improper implemented code ;)
(which is maybe disadvantage?):

TFoo($1).F;
TFooClass($1).F;

-- 
Best regards,
Maciej Izak
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