[Lazarus] Compare record

aradeonas aradeonas at operamail.com
Wed Mar 11 08:57:56 CET 2015


Thank you J├╝rgen,That is just a example but Its good to know there is
now way.
Thank you Sven for examples.I didn't know about advanced record support.

Regards,
Ara

On Tue, Mar 10, 2015, at 11:43 PM, Sven Barth wrote:
> On 10.03.2015 22:23, aradeonas wrote:
> > Hi,
> > How can I compare two record?
> > Like this :
> >
> >     type
> >     TRec=record
> >     na:string;
> >     end;
> >
> >     var
> >     R1,R2:TRec;
> >     Begin
> >     R1.na:='A';
> >     R2.na:='B';
> >     if R1<>R2 then
> >     Showmessage('Error')
> 
> At the declaration of TRec add this:
> 
> === code begin ===
> 
> operator = (aLeft, aRight: TRec): Boolean;
> 
> === code end ===
> 
> and then implement it like this:
> 
> === code begin ===
> 
> operator = (aLeft, aRight: TRec): Boolean;
> begin
>    Result := aLeft.na = aRight.na;
> end;
> 
> === code end ===
> 
> Alternatively you can declare the operator inside TRec if you enable 
> modeswitch advancedrecords:
> 
> === code begin ===
> type
>    TRec = record
>      na: String;
>      class operator = (aLeft, aRight: TRec): Boolean;
>    end;
> 
> === code end ===
> 
> Implementation:
> 
> === code begin ===
> 
> class operator TRec.=(aLeft, aRight: TRec): Boolean;
> begin
>    Result := aLeft,na = aRight.na;
> end;
> 
> === code end ===
> 
> This /should/ work though I did not test it by compilation.
> 
> Regards,
> Sven
> 
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