Anon function with undefined result yields no warning

[Lars Fosdal 1792]

Is this a known issue?
If you assign an anonymous function to a property, there is no warning if the result of the function is not defined.

Normally, a function where Result is not set will yield a warning.

program anon_method_func_result;

{$APPTYPE CONSOLE}
{$R *.res}

uses
  System.SysUtils;

type
  TConvertFunc<T> = reference to function(const invalue: string; out outvalue: T): Boolean;

  TValue<T> = class
  private
    FConverter: TConvertFunc<T>;
  public
    property Converter: TConvertFunc<T> read FConverter write FConverter;
    constructor Create;
  end;

constructor TValue<T>.Create;
begin
  FConverter := function(const inValue: string; out outvalue: T): Boolean
    begin
      outvalue := Default(T); 
      // Would have expected a warning here
      // since Result is never set
    end;
end;

begin
  try
    try
      var V := TValue<Integer>.Create;
      V.Free;
    except
      on E: Exception do
        Writeln(E.ClassName, ': ', E.Message);
    end;
  finally
  {$ifdef Debug}
    Write('Press Enter: ');
    Readln;
  {$endif}
  end;
end.

 

[Stefan Glienke 2002]

This issue is as old as generics are: https://quality.embarcadero.com/browse/RSP-10506

[Lars Fosdal 1792]

Well, I voted now, because I got bit by it.

[FredS 138]

3 hours ago, Stefan Glienke said:

as old as generics

Can't expect 'em to implement a new feature in under 5 years now..

[Guest]

Ouch. Thx!!!, one thingy off my plate. I vas bitten too. Did not have the time to dig in to that at that moment. Delphipraxis shows its use case again!

Edited September 2, 2021 by Guest

[Vincent Parrett 750]

On 8/27/2021 at 12:34 AM, FredS said:

Can't expect 'em to implement a new feature in under 5 years now..

And another 5 for it to actually work properly. 

[Vandrovnik 214]

On 8/26/2021 at 4:34 PM, FredS said:

Can't expect 'em to implement a new feature in under 5 years now..

This one was created on 11/Mar/15 🙂

[Guest]

3 hours ago, Vandrovnik said:

This one was created on 11/Mar/15 🙂

Please use ISO dates. I would have to do some research in order to know if you mean 2011-03-15 or 2015-03-11.

I would have to do research even to know if the "/" is information enough or if i need to know your "locale".

[Vandrovnik 214]

2 minutes ago, Dany Marmur said:

Please use ISO dates. I would have to do some research in order to know if you mean 2011-03-15 or 2015-03-11.

I would have to do research even to know if the "/" is information enough or if i need to know your "locale".

I just copies it from https://quality.embarcadero.com/browse/RSP-10506

I suppose it was created in 2015, but I would believe in 2011, too 🙂

Edited September 3, 2021 by Vandrovnik

[Fr0sT.Brutal 900]

29 minutes ago, Dany Marmur said:

Please use ISO dates

2015-03-11T23:04:42.837Z