I am not a python programmer, but am being forced to port one of my
(smalltalk) applications to python for pragmatic reasons (python is
embedded with a graphics package I am switching over to, so to use the
graphics package I am essentially forced to use python). Okay, enough
background.
At any rate, in my smalltalk solution, in order to avoid an if-then-
else chain of "if this command, do this function, else if this command
do another function..." I have commands set up in a dictionary. I
read the command integer, then key it into the dictionary to see what
method/function to call.
#Conceptual representation of dictionary with keys and values:
1: do_command1
2: do_command2
3: etc...
Trying to set up the same thing in python, it seems the lambda
expression is what I need. So I set up a simple class to test this,
with some simple code as follows:
###
class Blah(list):
pass
commands = {1: (lambda: Blah())}
###
This is accepted by the interpreter, no problem. If I type "commands"
into the interpreter I get the dictionary back showing the key '1'
attached to the lambda expression. If I type "commands[1]" into the
interpreter, I get the lambda function back. However, when I try to
invoke the lambda function with a "commands[1]()", I get a "global
name 'Blah' is not defined." I find this error odd, because if I do a
"Blah()", I get back a "[]" as expected (a list).
For a day, I have tried everything under the sun I know to try. For
instance, I thought perhaps lambdas don't work with methods, so I
wrapped the method call in a function. But I get the same error. I
have spent a day online googling this error, but have found nothing to
help me.
Can a guru out there help a python newbie with this? I figure you can
spot the problem in, oh, 5 seconds or less?
Thanks
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