Re: advantages or disadvantages of ADA over pascal or modula

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

Steve wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message
> news:av6gr5$cgael$1@ID-77047.news.dfncis.de...
>> Steve wrote:
>>
>> >   Ada has no equivalent to Pascal's "with" statement (if you've
> maintained
>> >   a
>> > lot of Pascal code, you know why this is an advantage).
>>
>> In fact Ada 95 has an equivalent of Pascal's "with":
>>
>> X : Some_Type renames An.Extremely.Long.Path.Name.Object;
> 
> After maintaining both Pascal and Ada code, I wholeheartedly disagree that
> Ada's renaming is equivalent to Pascal's with.
> 
> If you're trying to analyze Pascal code that looks something like:
> 
>   with a, b, c, d do
>     begin
>        field1 := fieldA
>     end;
> 
> Tracking down where the !@** field1 and fieldA come from is non trivial. 
> In fact if these fields exist in more than one of the a, b, c, d records
> it may be compiler dependent.
> 
> With Ada's renaming you can easily track a field back to its source.  You
> may have to sift through a few renamings, but in practice this is easy to
> do.

I agree that Ada's "rename" is better than Pascal's "with". However they 
both are responses to same problem. And neither is ideal. For example, 
people often write something like:

with Ada.IO_Exceptions;
package My_IO is
   End_Error : exception renames Ada.IO_Exception.End_Error;

and run into troubles when both Ada.IO_Exceptions and My_IO are "used". This 
causes some people to believe that "use" is inherently bad, which is not 
true.

-- 
Regards,
Dmitry A. Kazakov
www.dmitry-kazakov.de