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From: kilgallen@eisner.decus.org (Larry Kilgallen)
Subject: Re: PRECOMPILATION
Date: 1999/02/09
Message-ID: <1999Feb9.081125.1@eisner>#1/1
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References: <918556681.260459@dedale.pandemonium.fr>
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Newsgroups: comp.lang.ada
Date: 1999-02-09T00:00:00+00:00
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In article <918556681.260459@dedale.pandemonium.fr>, "=:-) Vincent" <vb@bruker.fr> writes:
> Are there precompilation instructions in Ada95,
> like in C (#ifdef,...etc) ? In other words, how can
> I set compilation conditions ?

Conditional compilation is explicitly omitted from Ada to avoid
a host of problems (not the least of which is readability issues).

For situations where you would use the C preprocessor to set varying
bounds, a small package declaring the current values is appropriate.
At compile-time you can substitute a different rendition of that
package which has different limits.

One strange case often handled by the C preprocessor is the definition
of named constants.  If this is your interest, take a look at Ada
enumerated types.

The piece of Ada which most closely matches C "macros" would be
Ada "generics".  At a rough level, you can first think of them
as "macros with type checking".  There are certainly (unsafe)
thinks you can do with C macros that are not possible with Ada
generics, but then again C macros are a crude shadow of the
macro capabilities of a language like Bliss.

Larry Kilgallen