[fpc-pascal] Proper preprocessor?

[Sven Barth]

Am 22.06.2018 um 10:12 schrieb Ryan Joseph:
>
>> On Jun 22, 2018, at 12:24 PM, Sven Barth via fpc-pascal <fpc-pascal at lists.freepascal.org> wrote:
>>
>> If $Assertions is set to Off the complete Assert() line will be absent from the compiled code.
>
> Good to know thanks.
>
>
> Here’s an example of something I’ve seen for debugging. I think that was kind of cool you could print types like that and I’m not sure how that would work in Pascal if at all. Maybe some RTTI magic perhaps.
>
> {$define typestr(t):='#t: '+IntToStr(sizeof(#t))}
>
> program macro_test;
> uses
> 	SysUtils;
>
> type
> 	MyRecord = record
> 		x, y, z: single;
> 	end;
>
> begin
> 	writeln(typestr(MyRecord)); // MyRecord: 12
> end.
In trunk that can be done rather nicely:

=== code begin ===

program ttest;

{$mode objfpc}

uses
   TypInfo;

type
   TMyRecord = record
     x, y, z: Single;
   end;

generic function TypeStr<T>: String;
var
   ti: PTypeInfo;
begin
   ti := PTypeInfo(TypeInfo(T));
   WriteStr(Result, ti^.Name, ': ', SizeOf(T));
end;

begin
   Writeln(specialize TypeStr<TMyRecord>);
end.

=== code end ===

Regards,
Sven