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delphiparametersdefault-parameters

Default parameter value for a TSomething in Delphi

I'd like to know if this is possible in Delphi (or if there's a clean way around it):

type
 TSomething = record
  X, Y : Integer;
 end;

GetSomething( x, y ) -> Returns record with those values.

... and then you have this function with TSomething as parameter, and you want to default it as

function Foo( Something : TSomething = GetSomething( 1, 3 );

The compiler spits an error here, however I'm not sure if there's a way around it!

Can this be done?

Solution

  • The easiest way is to use overloaded procedures:

    program TestOverloading;

{$APPTYPE CONSOLE}

uses
  SysUtils;

type
  TSomething = record
    X,Y : integer;
  end;

const
  cDefaultSomething : TSomething = (X:100; Y:200);

procedure Foo(aSomething : TSomething); overload;
begin
  writeln('X:',aSomething.X);
  writeln('Y:',aSomething.Y);
end;

procedure Foo; overload;
begin
  Foo(cDefaultSomething);
end;

begin
  Foo;
  readln;
end.