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From: Richard Riehle <richard@adaworks.com>
Newsgroups: comp.lang.ada
Subject: Re: ada vs. cpp
Date: Tue, 09 Oct 2001 22:18:02 -0700
Organization: AdaWorks Software Engineering
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Date: 2001-10-10T05:14:32+00:00
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"Robert*@" wrote:

> can GNAT implement a pragma
>
> pragma LOOSE_MODE_START

Such a pragma is not necessary.   There are two main issues
that annoy people who are accustomed to more loosely formed
languages:  the type model, and the visibility model.   Both of
these can be easily suppressed if one wishes to do so.

The default for every Ada construct is "type safe."   The default
for visibility is "visibility safe."    One may start with a language,
such as Ada, in which the defaults are "safe" and relax those
defaults through a variety of mechanisms.   In fact, we can quite
easily relax those defaults to the point that Ada becomes as
precarious as standard C or C++.

On the other hand, it is more difficult to start with a language where
the defaults are "unsafe" and increase the safety.   Such is the predicament

of the C and C++ programmer.   However diligently they may strive to
improve the safety of their code, the underlying default, "unsafe",
continues
to bedevil them.   Unfortunately, many of these attempts to make
the code more safe produces exactly the opposite result.

So, if you want unsafe Ada code, simply be liberal with use clauses,
don't define new data types (use the types in package Standard), make
everything a subtype of something else, use 'unchecked_access everywhere,
along with lots of other tricks to make Ada more like C.  Not very hard,
actually.   Stupid, yes.  Difficult, no.

Richard Riehle