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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Newbie question # 2
Date: Thu, 6 Aug 2020 23:08:00 +0300
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On 2020-08-06 22:45, Ian Douglas wrote:
> On Thursday, 6 August 2020 21:20:15 UTC+2, Niklas Holsti  wrote:
>>
>> Ada does not have such a feature.
> 
> I figured as much, probably "unsafe programming practice" at the end of the day.


I wouldn't say so. I think "namelist" input is a perfectly reasonable 
function to have in some programs, and is not particularly unsafe in any 
way -- if the programmer can limit the set of variables that can be 
named and changed by such input, which is the case in Fortran (and also 
in our various suggestions for implementing it in Ada).

PHP is (I believe) an interpreted language, so the symbol table is 
around at run-time, which makes it easy for PHP to support variables 
that refer to any other variable by its symbolic name. This can make 
"namelist" input in PHP unsafe, since the input can change any variable 
-- including variables that the programmer did not intend to be 
changeable in this way.

Ada is usually compiled, and the symbol table is not present when the 
compiled program runs, so it would be harder to implement a "namelist" 
input/output feature. But not impossible, as Fortran shows.


-- 
Niklas Holsti
niklas holsti tidorum fi
       .      @       .