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From: Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org>
Newsgroups: comp.lang.ada
Subject: Re: Pop function
Date: Wed, 14 Dec 2011 20:00:34 -0700
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Date: 2011-12-14T20:00:34-07:00
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On 12/14/2011 06:35 PM, Rego, P. wrote:
>> Your public interface should never use access types. Anonymous types are a
>> bad idea.
> Why so does the language allow it? Currently I could not think a better way
> of running over a pointer list: get the item, run the top of the list to the
> next one (and also keep the original pointer), free the original pointer and
> return the (newest) pointer to the top of the list. The problem I got was
> exactly when I tried to do this directly from the input access (so the
> anonymous type problem)

The language allows lots of things that are bad ideas: anonymous types, 
programming by extension, the list goes on. That's not a reason to use them.

While an unbounded list undoubtedly is implemented using access values, there is 
no reason to expose them to your clients.

The best way to run over a list is to reuse an existing implementation, such as 
Ada.Containers.Doubly_Linked_List, or PragmARC.List_Unbounded_Unprotected if you 
don't have access to a compiler for the current language. One wonders why you 
are trying to write another one.

>> Psychologists have found that the 1st few letters of a word are the most
>> important to recognizing what you're seeing. If many of your identifiers
>> start with the same few letters ("T_"), you are making your code harder to
>> read than necessary.
> I agree, but that's ok here. Think this as "be a general list type named
> T_List ..."

It's never OK to make your code harder to read.

-- 
Jeff Carter
"English bed-wetting types."
Monty Python & the Holy Grail
15

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