Re: [fpc-pascal] FPC bug or brain bug ?
On 27 May 2010, at 23:31, Yann Bat wrote: >> The compiler always adds a VMT if an object has a constructor or destructor. >> The reason is that the VMT also contains the instance size, which is used by >> the constructor helper to allocate the required amount of memory. > > Ok but why a different behaviour between [fpc | objfpc] mode and [tp | > delphi] mode ? It is allowed in Delphi and TP because they allow declaring typed constants of objects. I don't remember why it was disabled in the FPC modes, but that happened a long time ago (before the move from cvs to svn). Maybe someone else does. Jonas___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] FPC bug or brain bug ?
> The compiler always adds a VMT if an object has a constructor or destructor. > The reason is that the VMT also contains the instance size, which is used by > the constructor helper to allocate the required amount of memory. > Ok but why a different behaviour between [fpc | objfpc] mode and [tp | delphi] mode ? ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] FPC bug or brain bug ?
On 27 May 2010, at 16:01, Yann Bat wrote:
> I don't understand why compilation of the program below failed in fpc
> and objfpc mode. In tp and delphi mode it works as expected but in fpc
> and objfpc mode the compiler complains :
>
> blob.pas(17,3) Error: Constants of objects containing a VMT aren't allowed
> blob.pas(17,3) Fatal: Syntax error, ";" expected but "(" found
>
> Since my object has no virtual methods why a VMT ?
The compiler always adds a VMT if an object has a constructor or destructor.
The reason is that the VMT also contains the instance size, which is used by
the constructor helper to allocate the required amount of memory.
Jonas___
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Re: [fpc-pascal] FPC bug or brain bug ?
On 27 May 2010, at 21:51, Flávio Etrusco wrote:
> On Thu, May 27, 2010 at 11:01 AM, Yann Bat wrote:
>> type
>> TBlob = object
>>private
>> fId : LongInt;
>>
>>public
>> constructor Init;
>> function Id: LongInt;
>> end;
>>
>> PBlob=^TBlob;
>>
>> const
>> NullBlob : TBlob = (fId: 0);
>>
>> {=== TBlob ===}
>> constructor TBlob.Init;
>> begin
>> fId:=Random(1024) + 1;
>> end;
>>
>
> All TObject descendants have a VMT.
The above is not a TObject descendant. It's a TP-style object.
Jonas___
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Re: [fpc-pascal] FPC bug or brain bug ?
All TObject descendants have a VMT. The destructor is virtual, BTW.
-Flávio
On Thu, May 27, 2010 at 11:01 AM, Yann Bat wrote:
> Hi,
>
> I don't understand why compilation of the program below failed in fpc
> and objfpc mode. In tp and delphi mode it works as expected but in fpc
> and objfpc mode the compiler complains :
>
> blob.pas(17,3) Error: Constants of objects containing a VMT aren't allowed
> blob.pas(17,3) Fatal: Syntax error, ";" expected but "(" found
>
> Since my object has no virtual methods why a VMT ?
>
> Thanks.
>
>
> {$mode fpc}
> program Blob;
>
> type
> TBlob = object
> private
> fId : LongInt;
>
> public
> constructor Init;
> function Id: LongInt;
> end;
>
> PBlob=^TBlob;
>
> const
> NullBlob : TBlob = (fId: 0);
>
> {=== TBlob ===}
> constructor TBlob.Init;
> begin
> fId:=Random(1024) + 1;
> end;
>
> function TBlob.Id;
> begin
> Id:=fId;
> end;
>
> var
> B : TBlob;
> begin
> B:=NullBlob;
> WriteLn('B : ', B.Id);
>
> B.Init;
> WriteLn('B : ', B.Id);
> end.
> ___
> fpc-pascal maillist - fpc-pas...@lists.freepascal.org
> http://lists.freepascal.org/mailman/listinfo/fpc-pascal
>
___
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[fpc-pascal] FPC bug or brain bug ?
Hi,
I don't understand why compilation of the program below failed in fpc
and objfpc mode. In tp and delphi mode it works as expected but in fpc
and objfpc mode the compiler complains :
blob.pas(17,3) Error: Constants of objects containing a VMT aren't allowed
blob.pas(17,3) Fatal: Syntax error, ";" expected but "(" found
Since my object has no virtual methods why a VMT ?
Thanks.
{$mode fpc}
program Blob;
type
TBlob = object
private
fId : LongInt;
public
constructor Init;
function Id: LongInt;
end;
PBlob=^TBlob;
const
NullBlob : TBlob = (fId: 0);
{=== TBlob ===}
constructor TBlob.Init;
begin
fId:=Random(1024) + 1;
end;
function TBlob.Id;
begin
Id:=fId;
end;
var
B : TBlob;
begin
B:=NullBlob;
WriteLn('B : ', B.Id);
B.Init;
WriteLn('B : ', B.Id);
end.
___
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Re: [fpc-pascal] $CODEALIGN / Dynamic Arrays
On 27 May 2010, at 09:47, Helmut Hartl wrote: Does the $CODEALIGN (http://www.freepascal.org/docs-html/prog/progsu9.html ) directive influence dynamic array memory layout ? No, that directive only influences static code and data layout. I need an an aligned dynamic array of vectors for SSE operations. If the fpc dynamic array implementation supports alignment somehow I would not need an own implementation of an allocator. It doesn't support that. The proper way to support it would be to add some kind of vector data type to the compiler, whose rtti would indicate the alignment requirements (so the dynamic array allocation would take care of the alignment automatically). Jonas ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] $CODEALIGN / Dynamic Arrays
Does the $CODEALIGN (http://www.freepascal.org/docs-html/prog/progsu9.html) directive influence dynamic array memory layout ? I need an an aligned dynamic array of vectors for SSE operations. If the fpc dynamic array implementation supports alignment somehow I would not need an own implementation of an allocator. Any thoughts ? thanks, helmut ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
