[fpc-pascal] why can't we define class operator for old fashion object type, but ok for 'advanced record' type?

Michael Van Canneyt michael at freepascal.org
Wed Aug 15 11:05:38 CEST 2018



On Wed, 15 Aug 2018, Dennis wrote:

> I was trying to use a generic class TDictionary<T>  with type T. This 
> class has a method that compares a variable of T with another one.
>
> When I specialize a class using this TDictionary with a type:
>
> TSecurity = object
>   ....
> end;
>
>
> e.g. TNewDict = class(TDictionary<String, TSecurity>);
>
> it raise a compiler complaining that my TSecurity type has no operator = 
> defined.
>
> But when I try to add like this:
>
> TSecurity = object
>   ....
> class operator =  (constref aLeft, aRight: TSecurity ): Boolean; 
> //<---compiler Error: Procedure or Function expected
>
> end;

Did you try creating an "old-fashioned" = operator ?

Something like

Operator = (l,r : TSecurity) z : boolean;

begin
   // compare here
end;

Michael.


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