Antoon Pardon wrote: > Op 19-08-13 11:18, Chris Angelico schreef: <snip> >> The issue >> was regarding imports, and it's perfectly safe to import a constant, >> even if the interpreter doesn't protect you from then being a total >> idiot and changing it. > > Python doesn't have constants, so you statement about importing a > constant doesn't make sense. The point is that python doesn't provide > the mechanism for protecting names against reassignments. So you > don't know whether the variable you think of as a constant is so > in reality. And this from a pure language definition point of view. > That you can use tools that make the interpreter no longer behave > as the language should, doesn't negate that. >
Who cares what the language "protects?" I don't know any language whose protections can't be at least partially bypassed by clever foot-shooters. In any case, we all know that Python doesn't protect constants, so we're free to use the word in a friendlier way. A Python constant is what I use as a constant. I follow Pep-8 and make it all caps. So in any library I write struct_global.y would be a bug or a design flaw. (And with a single character name like that, it wouldn't be global in any case. Single character names are reserved for play code and for short loops) And if I subsequently change it in my calling code, it isn't a constant any more. If I rebind the name, it's not even the same variable any more. That's a bug, not an exception to the rule "don't use global variables." I also accept as a constant those values which are initialized sufficiently early in the code that most places will only ever see the final value. Those may be global without worry. -- DaveA -- http://mail.python.org/mailman/listinfo/python-list