On Mon, Aug 26, 2013 at 5:54 AM, chandan kumar <chandan_...@yahoo.co.in> wrote: > Hi all, > > Please see the below code,in which i'm verifying the global value in python. > > CHK=10 > > def test1(): > print "Value of CHK in test1",CHK > > def test2(): > CHK=40 > print "Value of CHK in test2",CHK > test1() > > def test3(): > global CHK > test2() > > test3() > > When i ran above code ,I'm getting vlaue of CHK as 40 in test2 method and 10 > in test1 method > Can somone explain me why the value of CHK is different in method test1 and > test2.
First, you are using incorrect terminology. You are defining functions here, not methods. A method is a 'function' that is contained within a class. Now, on to your question. You define CHK = 10 at the top of your code. CHK is a name defined within the global namespace of your file. In test1 you print CHK which will be the value of the global CHK. This is because, in python if a referenced name isn't present in the most immediate namespace (test1), it will look in the successive containing namespaces. to find the value. In test2 you create a new name CHK which is not the same as the outer CHK. The test2 CHK is only visible within the function. You assign it the value 40. When it executes, it prints 40. In test3 you let test3 know that CHK refers to the global (outer) name CHK. However when you call test2, you do it with no parameters. test2 knows nothing of your test3 internal names. You need to look up python namespaces, and scoping. I believe these are covered in the python.org tutorial. Be aware that if you learned another language (C, Java) that names will confuse you for a while in python. > > Best Regards, > Chandan > > > -- > http://mail.python.org/mailman/listinfo/python-list -- Joel Goldstick http://joelgoldstick.com -- http://mail.python.org/mailman/listinfo/python-list
