Re: local variables

[fjh@cs.mu.oz.au (Fergus Henderson)]

dewar@merv.cs.nyu.edu (Robert Dewar) writes:

>Instead you can just introduce a nested package:
>
>  package body Abstraction is
>    procedure Op1(...) is
>    begin
>      -- do something interesting
>    end Op1;
>
>    package body Encapsulate is
>
>      Counter : Integer := 0;  -- "static" variable used by Bump_Counter
>      procedure Bump_Counter(Next : out Integer) is
>      begin
>        Counter := Counter + 1;
>        Next := Counter;
>      end Bump_Counter;
>    end Encapsulate;
>  end Abstraction;
>
>
>The corresponding package spec might have
>
>  package Abstraction is
>    procedure Op1(...);
>
>    package Encapsulate is
>      procedure Bump_Counter (Next : out Integer);
>    end Encapsulate;
>
>    procedure Bump_Counter (Next : out Integer)
>      renames Encapsulate.Bump_Counter;
>
>  end Abstraction;

There's no need to put the package `Encapsulate' in the package
spec rather than the package body, is there?

I'd write this as

  package Abstraction is
    procedure Op1(...);

    procedure Bump_Counter (Next : out Integer);

  end Abstraction;

  package body Abstraction is
    procedure Bump_Counter (Next : out Integer)
      renames Encapsulate.Bump_Counter;

    package Encapsulate is
      procedure Bump_Counter (Next : out Integer);
    end Encapsulate;

    package body Encapsulate is
    	-- as above
    end Encapsulate;

    procedure Bump_Counter (Next : out Integer);
      renames Encapsulate.Bump_Counter;

  end Abstraction;

--
Fergus Henderson <fjh@cs.mu.oz.au>  |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>  |  of excellence is a lethal habit"
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