Extending write and str

[BeniBela]

Is it possible to extend write or str with new types?

So you can write:

Code: [Select]

  var x: TMyType;
  writeln(x:1:3);


[Leledumbo]

Is it possible to extend write or str with new types?

So you can write:

Code: [Select]

  var x: TMyType;
  writeln(x:1:3);


No. Note that Write[Ln] is mapped to compilerproc for the type of every given expression (argument). So, for:

Code: [Select]

WriteLn(1,'str');
it will be translated to:

Code: [Select]

fpc_writetext_shortint(1);
fpc_writetext_shortstr('str');
fpc_writeln_end;
real name might differ, but the concept is the same. Use fpc -al to know the actual translation.

[BeniBela]

No. No

That sucks...

[marcov]

Maybe classes can be made writeln()able due to their Tobject.Tostring method. I don't know if that is implemented though (in both FPC and Delphi)

[Leledumbo]

Maybe classes can be made writeln()able due to their Tobject.Tostring method. I don't know if that is implemented though (in both FPC and Delphi)

Now that's something that FPC could consider. It's been the concept in Java, C# and some other functional / pure oo languages. I prefer something that can be used on non-class types as well, though.

[A.S.]

Isn't it possible to declare an implicit type cast to string? Maybe record/type helper?

[BeniBela]

Even if toString would work, it cannot know the decimal formatting arguments