Chris Angelico at 2015/12/27 UTC+8 2:32:32PM wrote: > On Sun, Dec 27, 2015 at 3:11 PM, <jf...@ms4.hinet.net> wrote: > > Last night I noticed that Python does not resolve name in "def" during > > import, as C does in the compile/link stage, it was deferred until it was > > referenced (i.e. codes was executed). That's OK for Anyway codes has to be > > debugged sooner or later. I just have to get used to this style. > > > > But check these codes, it seems not. > > ------- > > x = 1 # a global variable > > print(x) > > > > class Test: > > x = 4 # a class attribute > > print(x) > > def func(self): > > print(x) > > > > x1 = Test() > > x1.x = 41 # a instance's attribute > > x1.func() # it's 1 but 41 was expect:-( > > -------- > > > > --Jach > > When you import this module, it runs all top-level code. So the > 'print' at the top will happen at import time. > > Among the top-level statements is a class definition. When that gets > run (to construct the class itself - distinct from instantiating it, > which happens further down), it builds a class by executing all the > statements in it, in order. That results in that value of x being > printed, and then defines a function. > > The function definition is being run at time of class construction, > and it creates a new attribute on the Test class. At that time, the > function body isn't actually executed (as you might expect). However, > it's worth noting that the function does not inherit class scope. The > unadorned name 'x' references the global. If you want to access > class-scope names from inside methods, you need to say 'self.x', which > also applies to instance attributes. That's what would do what you > expect here. > > ChrisA
Yea, right, it's in a method, not a function. A stupid mistake I had made:-( Thanks for your kindly patient with me, and Happy New Year to you:-) --Jach -- https://mail.python.org/mailman/listinfo/python-list