CoCoA » CoCoALib

Just a small question to throw in the room: Might it be worth considering to migrate to #pragma once?
Despite not being standardized, Wikipedia (https://en.wikipedia.org/wiki/Pragma_once#Portability) has a list of compilers and their support status (none of the recent versions specify "no").
Then, such issues (and also name clashes) cannot become a problem in the future anymore.

I also searched for any reasons not to use it and only found this response on StackOverflow: https://stackoverflow.com/a/34884735/5894824
However, a little more research reveals that the linked GCC bug 11569 has been fixed since 2003, and even on Reddit there are heated discussions about whether the points made in the SO post are correct (yet, nobody seems to have found failing scenarios).

Just ignore this comment, if it is not of interest/out of scope, by the way!

Thanks to Nico for the suggestion about #pragma. I read also the discussion about its pros and cons -- it is not clear what should happen if one tries to do "acrobatics" with the preprocessor... [not relevant to our use]

I am hesitating because, as Nico wrote, the #pragma is not standard (though recognized by "every" compiler).
At this point it requires less time just to check & correct the few include-guard symbols (already done) than to change every header file to use #pragma.

As for the CPP symbols in the interpreter... strictly that is not part of CoCoALib, so is not constrained by the coding standards of CoCoALib: in other words, there is no obligation to use the CoCoA_ prefix... but it might be a good idea anyway? Perhaps CoCoA5_ is a better prefix?