Ryan K wrote: > I'm thinking that perhaps this isn't a circular import and that I > don't understand importing. Here is a better explanation of my case (I > am using Django): > > I have file x.py that declares classes A, B, C.
Classes in Python are executable code, just like import-statements. That's why there is no Python equivalent to forward declarations in other languages; every name has to be known at the point where it occurs in the module. > There is also a file y.py that contains two methods T, U and the class > that we are talking about above. > > x.py uses a dispatcher system to connect a signal to methods T and U > in y.py so it does: from y import T, U. > > y.py needs to use classes A, B, C which is basically Menu and Link > (and some other class) above so I am thinking that if in y.py I have > from x import A, B, C that will cause a circular import? Yes. Having x import y and y import x creates a cycle. If you cannot avoid this by moving to a simpler design you can always introduce a third module z that imports x and y, and then explicitly resolves the circular references. > Is this not correct and if it isn't can you explain why? Does using > from ... import X, Y, Z, i.e. explicit imports avoid this problem or > does it exacerbate it? It has no effect. from module import X is equivalent to import module X = module.X del module # just the name, not the module itself Peter -- http://mail.python.org/mailman/listinfo/python-list
