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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Convention for naming of packages
Date: Sat, 11 Feb 2012 20:06:36 +0000
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Date: 2012-02-11T20:06:36+00:00
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"Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr> writes:

> Le Sat, 11 Feb 2012 11:17:41 +0100, Yannick Duchêne (Hibou57)
> <yannick_duchene@yahoo.fr> a écrit:
>
>> Le Sat, 11 Feb 2012 10:22:18 +0100, Simon Wright
>> <simon@pushface.org> a écrit:
>>> In most cases the subprogram name tells what it does, and the object
>>> parameter might just as well be called 'This'.
>
> Finally I will either not keep this one, or else, complete it. "This"
> as‑as and alone, don't map well on all subprograms.
>
> Fine with that:
>
>    Print (This => …);  -- Operation
>    Update (This => …); -- Operation
>
> But not with that:
>
>    Set_Weight (This => …, Value => …); -- Setter
>    Weight (This => …);                 -- Getter
>    Relation (This => …, Foo => …);     -- Expression

Personally I wouldn't use named association for the first
(dispatching/oblect) parameter. I saw Foo (This => This, ...) too
often. And now you'd say

   Foo.Set_Weight (Value => ...); or
   Foo.Set_Weight (To => ...);
   Bar := Foo.Weight;

> In any case, if things needs all to be properly named, naming from the
> user point of view, ends into bad name from the implementation/self
> point  of view. So a corresponding renaming could be advisable in
> implementation.
>
> Ex.
>
>    Me : constant Instance_Type renames This;
>    Me : constant Instance_Type renames On;
>    Me : constant Instance_Type renames Of;
>    Me : constant Instance_Type renames From;
>
> Would be rather pleasant to read and unlikely to make people shout
> "Hey, that's too much wordy! That's just bloat!".
>
> What's your feeling?

I think I would say it was bloat. One very quickly gets used to 'This'
(especially when using a code generator which always uses 'This' for the
object parameter!). But for one of the longer 'functional' names I was
mentioning earlier, it certainly could make sense.

In my current project I found myself saying

   type Attribute_Element is new Element with record
      ...
   end record;
   overriding
   procedure Resolve (A : in out Attribute_Element);
   overriding
   procedure Output (A : Attribute_Element; To : Ada.Text_IO.File_Type);

because 'This' seemed inappropriate. But it was only a vague feeling.