On Oct 9, 5:52 pm, Steven D'Aprano <st...@remove-this- cybersource.com.au> wrote: > On Sat, 09 Oct 2010 12:44:29 -0700, chad wrote: > > Given the following... > > > [cdal...@localhost oakland]$ python > > Python 2.6.2 (r262:71600, May 3 2009, 17:04:44) [GCC 4.1.1 20061011 > > (Red Hat 4.1.1-30)] on linux2 Type "help", "copyright", "credits" or > > "license" for more information. > >>>> class foo: > > ... x = 1 > > ... y = 2 > > ... > >>>> one = foo() > >>>> two = foo() > >>>> print one > > <__main__.foo instance at 0xb7f3a2ec> > >>>> print two > > <__main__.foo instance at 0xb7f3a16c> > >>>> one.x > > 1 > > > Is 'one' a reference or a name space? Also, in 'one.x'. would 'one' > > be the name space? > > 'one' is a name. Since it is a bound name, it naturally refers to some > object (in this case an instance of foo), which also makes it a reference. > > The object that 'one' is bound to is the namespace. The name itself is > not -- the name itself comes *from* a namespace (in this case the global > namespace). > > However, since people are lazy, and 98% of the time it makes no > difference, and it is long and tedious to say "the object which the name > 'one' is bound to is a namespace", people (including me) will often > shorten that to "'one' is a namespace". But remember that when people use > a name sometimes they're talking about the name itself and sometimes the > object it is bound to: > > > > >>> x = 123 # x applies to the name 'x'. > >>> print x # x applies to the object the name is bound to > 123 > >>> del x # x applies to the name 'x' > > Not all names are references: > > >>> spam > > Traceback (most recent call last): > File "<stdin>", line 1, in ? > NameError: name 'spam' is not defined > > Since the name 'spam' is not bound to any object, it is not a reference. > Likewise, given: > > def func(x, y): > pass > > the name 'func' is a name which is bound to a function object. The > function object includes two names 'x' and 'y'. Since they're not bound > to anything, they are not references *yet*, but when you call the > function, they become (temporarily) bound. > > Hope this helps.
Maybe I'm being a bit dense, but how something like [cdal...@localhost oakland]$ python Python 2.6.2 (r262:71600, May 3 2009, 17:04:44) [GCC 4.1.1 20061011 (Red Hat 4.1.1-30)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> spam Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'spam' is not defined >>> Generate an error, but something like >>> def foo(x, y): ... pass ... >>> Doesn't? I mean, in the first case, 'spam' isn't bound to anything. Likewise, in the second case, both 'x' and 'y' aren't bound to anything. I don't see why the interpreter doesn't complain about 'x' and 'y' not being defined. Chad -- http://mail.python.org/mailman/listinfo/python-list
