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Mailing lists / fpc-devel / 2007-05

which constant expression?

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Mario R. Carro

Hi. Why does this fail to compile with FPC 2.3.1? (from ZeosLib):

procedure TZExpression.SetTokenizer(Value: IZTokenizer);
var
  Parser: TZExpressionParser;
begin
  FTokenizer := Value;
  TZExpressionParser(FParser).Tokenizer := Value; // <-- This line fails
end;

FParser is declared as TObject and assigned a is a property of TZExpressionParser of type IZTokenizer that gives direct access to the field FTokenizer of the same class.

The error message says:

ZExpression.pas(479,20) Error: Can't take the address of constant expressions

I googled a little and found that this error message is associated to trying to use a property as a var parameter or to try to modify a member of a value returned by a property, but this isn't any of those cases. May the problem be the property is of an interface type?

Thanks,
Mario

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Jonas Maebe
to Daniël Mantione
Daniël Mantione wrote 7 lines
Op Sat, 26 May 2007, schreef Mario R. Carro: > Hi. Why does this fail to compile with FPC 2.3.1? (from ZeosLib): Please read http://lists.freepascal.org/lists/fpc-pascal/2007-May/ 013794.html and the replies.

This is actually a different situation. I'm testing a fix, as the code posted (at least what I guess it should be when you add enough things so it becomes compilable -- please, people, /always/ provide a fully compilable sample so we don't have to guess what your code looks like) should work.

Jonas

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Mario R. Carro
to Jonas Maebe
Jonas Maebe wrote 14 lines
On 26 May 2007, at 23:40, Mario R. Carro wrote: > Hi. Why does this fail to compile with FPC 2.3.1? (from ZeosLib): > > procedure TZExpression.SetTokenizer(Value: IZTokenizer); > var > Parser: TZExpressionParser; > begin > FTokenizer := Value; > TZExpressionParser(FParser).Tokenizer := Value; // <-- This line > fails > end; Fixed. 
Great! But look at the attached test: The compilation of the
line "ArrayInts := nil" fails with the same error. Rewriting it
as "FArrayInts := nil" lets the compiler accept it. I'm using r7494.
Jonas

Thanks,
Mario

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Jonas Maebe
to Mario R. Carro
Mario R. Carro wrote
Great! But look at the attached test: The compilation of the line "ArrayInts := nil" fails with the same error. Rewriting it as "FArrayInts := nil" lets the compiler accept it. I'm using r7494.

Thanks, fixed.

Jonas

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Mario R. Carro
to Jonas Maebe
Jonas Maebe wrote 9 lines
On 28 May 2007, at 15:00, Mario R. Carro wrote: > Great! But look at the attached test: The compilation of the > line "ArrayInts := nil" fails with the same error. Rewriting it > as "FArrayInts := nil" lets the compiler accept it. I'm using r7494. Thanks, fixed. Jonas

With this fix ZeosLib-testing compiles out of the box with FPC from SVN (except a wrong ifdef in ZeosLib that I'll ask them to fix).

Thanks,
Mario

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Joost van der Sluis
to Mario R. Carro
Mario R. Carro wrote 13 lines
On Monday 28 May 2007, Jonas Maebe wrote: > On 28 May 2007, at 15:00, Mario R. Carro wrote: > > Great! But look at the attached test: The compilation of the > > line "ArrayInts := nil" fails with the same error. Rewriting it > > as "FArrayInts := nil" lets the compiler accept it. I'm using r7494. > > Thanks, fixed. > > > Jonas With this fix ZeosLib-testing compiles out of the box with FPC from SVN (except a wrong ifdef in ZeosLib that I'll ask them to fix).

You'd better test it with fpc 2.1.4 aka 2.2.0-beta. Changes in svn can break things again.

Joost.

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Mario R. Carro
to Joost van der Sluis
Joost van der Sluis wrote 18 lines
On Mon, 2007-05-28 at 13:34 -0300, Mario R. Carro wrote: > On Monday 28 May 2007, Jonas Maebe wrote: > > On 28 May 2007, at 15:00, Mario R. Carro wrote: > > > Great! But look at the attached test: The compilation of the > > > line "ArrayInts := nil" fails with the same error. Rewriting it > > > as "FArrayInts := nil" lets the compiler accept it. I'm using r7494. > > > > Thanks, fixed. > > > > > > Jonas > > With this fix ZeosLib-testing compiles out of the box with FPC from SVN > (except a wrong ifdef in ZeosLib that I'll ask them to fix). You'd better test it with fpc 2.1.4 aka 2.2.0-beta. Changes in svn can break things again.

Ok, I'll do that.

Joost.

Thanks,
Mario

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