CODEWITHSUNDEEP
pythonexpressionmaya
Alexander Sapphire
Alexander Sapphire

Reputation: 13

Maya Python - How to Call Function Using cmds.expression()

My current project requires that I call a particular class function whenever the timeline is scrubbed or selected (per frame, basically). I have tested the use of cmds.expression(s = 'print "hello "') and found that, every time I moused over a different frame while scrubbing the timeline, it printed "hello " just as I expected. However, whenever I tried to call a class function (or any other defined function for that matter), I receive errors. Here is a general synopsis of my code:

class DummyClass:
    def __init__(self):
        self.name = 'Dummy'

    def displayName():
        print self.name

d = DummyClass()
cmds.expression(s = 'd.displayName()')

I receive the error: # Error: line 0: Cannot find procedure "d.displayName". #

And this is a general synopsis of me trying to see whether or not I could call any function definition, let alone a class:

def foo():
    print 'Success!'

cmds.expression(s = 'foo()')

I receive the error: # NameError: name 'foo' is not defined #

Maybe I just don't understand what cmds.expression() truly does. Will it only work with external python files or something? I can get cmds.expression(s = 'print "hello "') to work, but nothing else within the same script can be found, apparently. Am I taking the wrong approach? Am I missing syntax? I have spent many hours doing research on the matter and have gotten nowhere.

How do I call a defined function, from within a class or otherwise, using cmds.expression? If that's not possible, is there a similar command that can do the trick?

Upvotes: 1

Views: 2854

Answers (1)

Andy Jazz
Andy Jazz

Reputation: 58493

Flag s sets the expression string. This type of expression is undoable, queryable and editable.

You should use it this way:

import maya.cmds as mc
mc.expression( s = 'pSphere1.translateX = cos(time/2)*10' )

But calling Python defined functions you can the same way as described in SO post:

How do I use Def Function strings in maya

Upvotes: 1

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