>I just completed an assignment out of Learning Python
> in which I used the Cmd class from the cmd module to
> create a little shell:
> Originally, I called the function 'ls', but when I did
> that, the function didn't work when I typed 'ls' at
> the prompt. When I looked in the back of the book, I
> saw the name the authors gave their function, which
> was 'do_ls'. When I changed the function's name to
> do_ls, the function worked when I typed 'ls' at the
> prompt. Does anyone know why this happened?
Its just how the module works - many GUI frameworks
adopt a similar convention - eg Visual Basic command handlers.
My guess os that cmd builds the command string then uses eval() to
execute the function, but I could be wrong. But in general frameworks
like cmd will either:
1) expect some kind of standard naming scheme
(like cmd apparently does) or
2) Have some form of function registration mechanism so that code
looks like
def someFunc():
# blah, blah
registerFunc("someCommand', someFunc)
def another():
# and more here
registerFunc("another", another)
Or sometimes as a table:
def foo(): # blah
def baz(): # more blah
registerFuncs( {"commandFoo": foo, "commandBaz": baz})
wxPython (Or more accurately its underlying framework, wxWidgets)
uses this second approach, for example. As does Microsoft in their
MFC C++ framework.
HTH
Alan G
Author of the learn to program web tutor
http://www.freenetpages.co.uk/hp/alan.gauld
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