Re: Running a preprocessor from GPS?

["Randy Brukardt" <randy@rrsoftware.com>]

"EGarrulo" <egarrulo@gmail.com> wrote in message 
news:d5a73210-a67f-4d21-8b16-536af10ab157@googlegroups.com...
> On Wednesday, July 29, 2015 at 10:32:16 PM UTC+2, Randy Brukardt wrote:
...
>> In Ada terms, typing is something done at compile-time. Ada does not have
>> runtime typing (one could imagine tag checks to be runtime typing, but
>> that's a check in Ada, not related to typing).
>
> But is this a valid excuse? Aren't programming languages supposed to
> let programmers write useful programs?

Within the language philosophy. If writing *your* useful programs is too 
hard, then you are probably using the wrong language (or you need some 
re-education, which I think applies more to the current case ;-).

...
> If Ada offered runtime typing by means of a type `Any`, then `Printf`
> could be trivially written as:
>
>   type Printf_Arguments is array (Positive range <>) of Any;
>
>   procedure Printf (Format : String; Arguments : Printf_Arguments);

Surely, at the cost of all compile-time checking (because there isn't any). 
And there couldn't be any useful runtime checking, either (at least not 
unless Ada added Multiple Inheritance, which is unlikely), so such a 
construct would be unsafe. (Exactly how unsafe depends on the capabilities 
of the format string.)

...
>> > Generics *are* glorified macros anyway, in a sense.
>>
>> This is an especial sore point with me!
>>
>> Formally in the Ada RM they are, which causes all manner of nonsense 
>> effects
>> which then get erased by special rules. Stupid.
>
> What do you mean?  Conceptually, generics are macros.

Definitely not; that's the problem that programmers with extensive C++ 
knowledge don't understand, because they *are* macros in C++. But in Ada, 
the contents of the source text is not what gets duplicated (even though the 
RM mistakenly describes it that way -- definitely a sore point with me). 
Niklas explained the model in far more detail, so I won't repeat it here --  
but the "generic contract" is considered critically important to the 
language design (just like avoiding privacy violations is). It is very 
unlikely that we would ever allow anything that would make an Ada generic 
work like a macro.

                                  Randy.