How to fix an undefined method in a simple class in Python for maya script?

Question

To get a better understanding of how classes are called and work, I have been trying to take a handful of functions that have been working for me in a simple script I have written that snaps one object to another in 3D space in maya.

When I put them in a class and try to run the code, the error message that I got was:

Error: NameError: file line 10: global name 'runSelected' is not defined #

I thought that this might be because I was calling methods that did not have self. in front of them. I tried doing this though and am still getting an error which is:

Error: NameError: file line 35: global name 'self' is not defined #

The script is run after selecting two objects in 3D space in maya and kicked off by running:

Align()

The code for the class is below:

#Class for snapping one object to another in Maya.

import maya.cmds as mc


class Align(object):

    def __init__(self):
        #starts the runSelected Method
        self.runSelected()       

    def selectionCheck(mySel):
        #checks that 2 ojects are created, returns True if so, Flase if not.
        if len(mySel) == 2:   
           print "Great! Two selected"  
           return True

        elif len(mySel) == 0: 
           print "Nothing Selected to constrain!"
           return False   

    def createWindow():
        #This creates a simple dialogue window that gives a message.
        mc.confirmDialog(title='Align Objects', m ="Instructions: You need to select two objects to constrain.")

    def runConstrainDelete(mySel):
        #Creates a parent constraint, does not maintain offset and then deletes the constraint when object is moved.Clears selection.
        myParentConstraint = mc.parentConstraint(mySel[0], mySel[1], mo=False)
        mc.delete(myParentConstraint)
        mc.select (clear=True)

    def runSelected(object):
        #Creates a list of objects selected. Runs selection check
        mySel = mc.ls(sl =True)
        result_Sel_Check = self.selectionCheck(mySel)

        #if statement handles if a warning window or the rest of the script should be run.
        if result_Sel_Check == False:
            self.createWindow()    
        else:
            self.runConstrainDelete(mySel)


test_Align = Align()

Answer 1

When defining instance method you need to explicitly pass self as a first parameter of a method. For example def runSelected(object): should be changed to def runSelected(self, object):, only then you can access self in method body. You should read up on python self and instance methods to gain some intuition.