[fpc-devel]Proposal for audo-destructors

[Vincent Snijders]

Nico Aragón wrote:

> Hello,
> 
> On Sun, 12 Sep 2004 13:07:24 +0200 (CEST), marcov at stack.nl (Marco van
> de Voort) wrote:
> 
> 
>>>Absence of automatic construction/destruction of 
>>>classes is very painfull and it can significantly 
>>>degrade the
>>>development process (i.e. smart pointers and RAII are 
>>>impossible).
>>
>>Very painfull is a bit exaggerated :-)
> 
> 
> Sometimes, it's. F.i.:
> 
>   procedure CopyFile(SourceFileName, TargetFileName: string);
>   var
>       s, t: TStream;
>   begin
>       s := TFileStream.Create(SourceFileName, fmOpenRead);
>       try
>           t := TFileStream.Create(TargetFileName, fmCreate);
>           try
>               t.CopyFrom(s);
>           finally
>               t.Free;
>           end;
>       finally
>           s.Free;
>       end;
>   end;

Except in the original proposal, constructor were to be compiler 
generated too. That is impossible in this example, since the constructor 
has parameters.

> Imagine you could write:
> 
>   procedure CopyFile(SourceFileName, TargetFileName: string);
>   auto
>       s, t: TStream;
>   begin
>       s := TFileStream.Create(SourceFileName, fmOpenRead);
>       t := TFileStream.Create(TargetFileName, fmCreate);
>       t.CopyFrom(s);
>   end;
> 
> Eight lines instead of sixteen and much clearer. The compiler would
> internally translate it to something like:
> 

Vincent.