In article <536decca$0$29980$c3e8da3$54964...@news.astraweb.com>, <SNIP> >Personally, I don't imagine that there ever could be a language where >variables were first class values *exactly* the same as ints, strings, >floats etc. Otherwise, how could you tell the difference between a >function which operated on the variable itself, and one which operated on >the value contained by the value? The best you can do is for variables to >be "second class" -- you can do these things to them, but you need >special syntax or declarations to tell the compiler you're operating on >the variable rather than the variable's value. E.g. Pascal and Algol have >syntax for instructing the compiler when to pass a variable as a value, >and when to pass the value. C gives you nothing.
You're talking about Algol, but there is a great distinction between Algol60 and Algol68. Algol68 through the ref keyword goes a long way towards making variables first class citizens. E.g. although `` int i'' in Algol68 means practically the same as in C, it is defined as being an abbreviation of 'ref' 'int' i = 'loc' 'int'; This means so much that i is a reference to an otherwise unnamed int that is allocated locally. Furthermore you can't break the tie between i and that int (because you use =, you could have used := ) Because I refers to that location you can change it by i:=1; Note that the left side *must* be a reference. You can't change an int, you can only change the content of a memory place you can refer to. Now you can define 'ref' 'int' pi; pi := i; van Wijngaarden and crue pretty much nailed it, IMO. <SNIP> >-- >Steven D'Aprano >http://import-that.dreamwidth.org/ Groetjes Albert -- Albert van der Horst, UTRECHT,THE NETHERLANDS Economic growth -- being exponential -- ultimately falters. albert@spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst -- https://mail.python.org/mailman/listinfo/python-list
