NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c++-part2/14664

Internet Message Format | 1996-08-05 | 1.8 KB

Path: wdl1.wdl.loral.com!dst17!mab
From: [e-mail] (Mark A Biggar)
Newsgroups: comp.lang.ada,comp.lang.c++
Subject: Re: some questions re. Ada/GNAT from a C++/GCC user
Date: 1 Apr 1996 16:17:13 GMT
Organization: Loral Western Development Labs
Message-ID: <4jovi9$[e-mail]>
References: <[e-mail]> <[e-mail]> <[e-mail]>
NNTP-Posting-Host: dst17.wdl.loral.com

In article <[e-mail]> [e-mail] writes:
>   > Why doesn't Ada 95 allow declarations to be interspersed with ordinary
>   > statements as C++ does?  (Or does it?  _Ada as a Second Language_ is a
>   > big book!)  It seems to me that the C++ approach is a small but
>   > definite win.  Does it interact very badly somehow with all those
>   > guarantees on elaboration order?
>
>   To intersperse declarations, you have to use a block_statement, like
>   this:
>
>       for I in Some_String'Range loop -- I wish I could easily use an iterator here ;-)
>       declare
>           X: constant Character := Some_String(I);
>       begin
>           ...
>       end;
>       end loop;
>
>   To me, the "declare", "begin", and "end" are just useless verbosity.
>   I prefer the C++ rule.
>
>Yes, this seems needlessly verbose. Any Ada guru have a good reason why it has
>to be this way?

Yeah, 2 reasons.  The first goes clear back to the original Ada Strawman
documnt which calls for a clear distinction between declarations and code
statements.  The second reason is that is also the method of wraping an
exception handler around soem arbitary piece of code:

for I in Some_String'Range loop
    declare
        X: constant Character := Some_String(I);
    begin
        ...
    exception
        when ... ;
    end;
end loop;


--
Mark Biggar
[e-mail]