[fpc-devel] Delphi anonymous methods

[Boian Mitov]

Or even more drastic example like this one:

AAttributes := TRTRtti.GetType( 
Component.ClassType() ).GetCustomAttributes( 
TVLCommonFilterHostedPreviewAttribute, True );
for AAttribute in AAttributes do
  if( AAttribute is TLPComponentEditorAttribute ) then
    begin
    AAttrItem := GComponentEditorAttributeList.Find(
                      function( AItem : IComponentEditorAttributeItem ) : 
Boolean
                      var
                        AAttributes     : IRTAttributes;
                        AAttributeClass : TCustomAttributeClass;

                      begin
                        AAttributeClass := 
AItem.GetInstance().AttributeClass;
                        AAttributes := TRTRtti.GetType( 
Component.ClassType() ).GetCustomAttributes( TLPSuppressAttribute, True );
                        if( AAttributes.Find(
                                function ( ASupressAttribute : 
TCustomAttribute ) : Boolean
                                begin
                                  Result := ( AAttributeClass = 
TLPSuppressAttribute( ASupressAttribute ).Attribute );
                                end
                              ) <> NIL ) then
                          Exit( False );

                        Result := ( AAttribute is AAttributeClass );
                      end
                   );

    Exit( AAttrItem.GetInstance().ComponentEditor.Create( Component, 
Designer ));
    end;

Try to write this without anonymous methods ;-) :-D .


With best regards,
Boian Mitov

-------------------------------------------------------
Mitov Software
www.mitov.com
-------------------------------------------------------
-----Original Message----- 
From: Martin
Sent: Sunday, March 03, 2013 8:42 PM
To: FPC developers' list
Subject: Re: [fpc-devel] Delphi anonymous methods

On 04/03/2013 03:49, Boian Mitov wrote:
> Yes, really!
> Then again this is over 4 mln mines of code after all. :-D
> Thank you for letting me know what closure is :-D . Can you imagine, me 
> being component vendor for over 16 years and not knowing what closure is 
> :-D.
Did I? Wow, I didn't know I did. Didn't mean to neither. I was just
checking, if you accidentally used the wrong word. (Happens to everyone,
even the very best / so no judgement implied)

> Anonymous methods lead to a different way of thinking altogether and allow 
> you to do things that you can't even imagine with closures ;-) .
> And they make the code infinitely easier to read, especially if like me 
> this is a huge codebase ;-) . After all we sell well over 400 components 
> not to mention some of our other Delphi based products ;-) .
> Sure, if you have small code you can do just fine with closures, as I have 
> for many years, then again I did just fine without having classes, and 
> objects in the old days, and also did fine in the older days in Assembler 
> :-D .
> So according to this logic, we really should be doing everything in 
> machine code (as I actually did briefly 24 years ago :-D ), who needs new 
> features such as those whatmacallit... ohhh yeahh... "compilers" :-D .
Well I give you the benefit of the doubt, and believe you. But that does
not help me, because I still do not know which case you are talking
about.... So for my benefit, please enlighten me with an example.

>From your above statement, I take, that you already used closures, and
that the big improvements really happened of a result of anonymous methods.
Just to be save, let me state the obvious: We are talking of dropping
the function name; and introducing the ability, to declare the function
anywhere within the code (probably the latter being the important). That
are the 2 only things, that anonymous methods do offer? (OR am I missing
anything?)

If so then I do not see how they save 20000 lines?
- The name is part of the declaration line, SO it should not affect the
line count at all). Unless you always write the name on a separate line
(which I would consider a very special case)
- the place of declaration also does not change the line count.


> -----Original Message----- From: Martin
> Sent: Sunday, March 03, 2013 7:38 PM
> To: FPC developers' list
> Subject: Re: [fpc-devel] Delphi anonymous methods
>
> On 04/03/2013 01:47, Boian Mitov wrote:
> Really, just by dropping the names? Or did you mean, you did all that by
> using closures?
>
> Closures, do not need to be written/declared in the middle of other code
> (in-line)

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