Re: [fpc-pascal] EnumToString

2011-11-01 Thread Yann Bat 
You can directly write enums with Write or WriteLn and convert enums
to strings with WriteStr.

program EnumStr;
{$mode objfpc}{$H+}

type
  TColor = (cRed, cGreen, cBlue, cYellow);

function ColorToStr(C: TColor) : String;
begin
  WriteStr(Result, C);
end;

var
  Color : TColor;
begin
  for Color in TColor do
WriteLn(ColorToStr(Color));
end.

2011/11/1 Juha Manninen :
> Hi
> I remember there is a way to get a string representation of an enumerated
> type directly without using a lookup string array, but I forgot the syntax.
> Lazarus uses only lookup arrays, maybe because the other syntax is new.
> How is the syntax?
> Juha
>
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Re: [fpc-pascal] 2 bugs ???

2011-09-07 Thread Yann Bat 
2011/9/7 Leonardo M. Ramé :
> From: Yann Bat 
>
>
> The error message is correct, because inside the scope of method  Bug, _T 
> points to nil, and the size of nil is 0, so 1 div 0 raises the error.
>

I think that SizeOf(_T) should be unknown rather than 0. The compiler
should not make any assumption about _T before specialization.

> What about using Result := 100 div SizeOf(FField); ?

Same error with SizeOf(FField).



>
> Leonardo.
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Re: [fpc-pascal] 2 bugs ???Q

2011-09-07 Thread Yann Bat 
Thanks. You've just found bug number 3 ! :-)

But #1 and #2 are alway here.



2011/9/7 Marco van de Voort :
> In our previous episode, Yann Bat said:
>> I am trying to learn freepascal generics and I think that I have found 2 
>> bugs.
>
>> var
>>   V: TGenInt;
>> begin
>>   V.Create(589);
>
> This is no pascal way of creating a class. Use v:=tgenint.create;
>
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[fpc-pascal] 2 bugs ???

2011-09-07 Thread Yann Bat 
Hi,

I am trying to learn freepascal generics and I think that I have found 2 bugs.

Tested with FPC 2.4.4 Linux x86

==
= BUG 1 - with SizeOf =
==
program SizeOfBug;
{$mode objfpc}{$H+}

type
  generic TGen<_T> = class(TObject)
private
  FField: _T;
public
  constructor Create(Val: _T);

  function Bug: Integer;
  end;

{--- TGen.Create ---}
constructor TGen.Create(Val: _T);
begin
  inherited Create;
  FField := Val;
end;

{--- TGen.Bug ---}
function TGen.Bug : Integer;
begin
  Result := 10 div SizeOf(_T);  // *** DIVISION BY ZERO ***

  // THE FOLLOWING CODE IS OK !
  //
  // var
  //   S: Integer;
  // begin
  //   S := SizeOf(_T);
  //   Result := 10 div S;
end;

type
  TGenInt = specialize TGen;

var
  V: TGenInt;
begin
  V.Create(589);
  WriteLn('V.Bug = ', V.Bug);
  V.Free;
end.

==
= BUG 2 - with WriteLn =
==

program WriteLnBug;
{$mode objfpc}{$H+}

type
  generic TGen<_T> = class(TObject)
private
  FField: _T;
public
  constructor Create(Val: _T);

  procedure Bug;
  end;

{--- TGen.Create ---}
constructor TGen.Create(Val: _T);
begin
  inherited Create;
  FField := Val;
end;

{--- TGen.Bug ---}
procedure TGen.Bug;
begin
  WriteLn('FField = ', FField);  // *** CAN'T READ OR WRITE VARIABLES
OF THIS TYPE ***
end;

type
  TGenInt = specialize TGen;

var
  V: TGenInt;
begin
  V.Create(589);
  V.Bug;
  V.Free;
end.
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Re: [fpc-pascal] Length bug ?

2010-10-11 Thread Yann Bat 
2010/10/11 Michael Van Canneyt :
>
> Please enter a bug report for this.
>

Done.

http://mantis.freepascal.org/view.php?id=17604
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[fpc-pascal] Length bug ?

2010-10-11 Thread Yann Bat 
Hi,

I think I have found a bug in FPC 2.4.0. Tested under Windows XP 32
bits and Linux 32 bits.

program TestLength;
begin
  WriteLn('L =', Length('') );
end.

This program gives L = 1 but I think it should give L = 0.

Is this really a bug ? Can you reproduce this ?

Thanks
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Re: [fpc-pascal] FPC bug or brain bug ?

2010-05-28 Thread Yann Bat 
> It is allowed in Delphi and TP because they allow declaring typed constants 
> of objects.

Exactly what I wanted to use. I'll have to use constructors so.

Thank you for your help.
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Re: [fpc-pascal] FPC bug or brain bug ?

2010-05-27 Thread Yann Bat 
> 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 ?
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[fpc-pascal] FPC bug or brain bug ?

2010-05-27 Thread Yann Bat 
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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[fpc-pascal] Re: Memory allocation problem

2010-02-26 Thread Yann Bat 
Please forgot my stupid question.

GetMem works perfectly as described in the documentation. My problem
cames from an another part of my program.

Yann
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[fpc-pascal] Memory allocation problem

2010-02-26 Thread Yann Bat 
Hi,

I'm looking for a function or a procedure that tries to allocate
memory and return nil on failure.

GetMem seems to be a good candidate but it doesn't works as expected.
The FreePascal documentations
(http://www.freepascal.org/docs-html/rtl/system/getmem.html) tells
that it returns nil on failure but it raises an out of memory
exception (may be bug ???) when I try to allocates too much memory on
linux (I haven't try on windows).

Since my code is in fpc mode I can't catch the exeption. I know that
there is a ReturnNilIfGrowHeapFails variable but this changes the
behaviour of the all memory allocation system... I think I can do
something like the following code but I fear it's not thread safe.

function GetMemOrNil(size: PtrInt): pointer;
var
  tmp : boolean;
begin
  tmp:=ReturnNilIfGrowHeapFails;
  ReturnNilIfGrowHeapFails:=true;
  GetMemOrNil:=GetMem(size);
  ReturnNilIfGrowHeapFails:=tmp;
end;

Yann

Ps : Sorry for poor english.  I hope you can understand me.
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