Re: Is there a way to do large block of source code comments

[Stefan.Lucks@uni-weimar.de]

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On Tue, 2 Sep 2014, robin.vowels@gmail.com wrote:

> On Tuesday, September 2, 2014 5:04:21 AM UTC+10, Jeffrey Carter wrote:
>> On 09/01/2014 10:24 AM, g.nospam@gmail.com wrote:
>>> is there a way to handle several lines at a time without having to do -- on every line?
>>> like /* ...
>>
>>>            ...
>>
>>>         */
>> No, this was explicitly omitted. See the Ada-83 Rationale 2.1:
>> [...] Such comments would require a closing comment delimiter and this 
>> would again raise the dangers [...] without the programmer realizing it, so
>> that the program would not mean what he thinks.
>
> When a block of code is to be omitted (temporarily or semi-permanently)
> it's convenient to have something like /* and */ as comment markers.

Convenient: Yes! Safe: No!

The issue is that nesting /* and */ makes makes it difficult to parse 
programs -- not for the computer, but for humans. At the time Ada has been 
originally designed, syntax highlighting editors where not so common as 
they where today (to say the least). The designers of Ada decided to avoid 
these issues.

> The above quotation is mere hype, like the author's justification for 
> omitting exponentiation in Pascal, somehow more convenient to use log 
> and exp instead!

Nonsense!

You don't need to agree with that decision by the Ada designers -- I am 
not sure if I would agree with that either -- but you should understand 
that it was something the Ada designers had carefully considered before, 
very much unlike the Pascal example you gave, which was really an ad-hoc 
decision, for the convenience of the compiler writer.

Now, I actually think it would have been possible to have block comments 
the Ada way (and is still possible for Ada 202X): Allow block comments 
(I'd suggest Pascal's "(*" and "*)" for their brackets but that is a 
matter of taste). Just prohibit nesting! I.e., any "(*" inside a block 
comment is a syntax error. Conventional "--" comments are allowed, and any 
"(*" and "*)" inside a conventional comment are allowed and ignored (i.e., 
not treated as block comment brackets).

This language feature would allow to easily comment out large program 
parts without safety issues. But I doubt there is actually much demand for 
that in the Ada community!

------  I  love  the  taste  of  Cryptanalysis  in  the morning!  ------
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--Stefan.Lucks (at) uni-weimar.de, Bauhaus-Universität Weimar, Germany--