How to make Python Wait for input?

I am using python in Maya, a 3D animation package. I would loved to run a definition (A) but within that definition I want another definiton (B) that requires a valid object selection. The script will kept going until one is made (in def B) and I want to continue with my script (def A) with a returned value from def B. How can I tell def A to wait until a valid returned value is retreived from def B?

So short question: How can I make python wait for a valid returned value to be received?

I hope that make sense and thank you in advance for your time.

C

example:

def commandA () :
   result = commandB()
   ### Wait for a value here ###
   if result == "OMG its a valid selection" :
      do_another_commandC()

def commandB () :
   # This command is kept running until a desired type of selection is made
   maya.mel.eval("scriptjob "making a valid selection" -type polygon")
   if selection == "polygon" :
      return "OMG its a valid selection"
   else :
      commandB()

I need some thing in ### line for the function to wait until a desired return is received, then continue on with the rest. At the moment the function just run everything regardless.

Thank you

---

If the scope of commandB() is limited to commandA() you may consider using closures (what is a closure?)

or simply nested python functions (http://effbot.org/zone/closure.htm , http://www.devshed.com/c/a/Python/Nested-Functions-in-Python/)

in any part of your code considering "result = commandB()" statement,

the interpretter should wait until something is returned from commandB() and assigned to result, before proceeding to the next line to be executed.

---

You could just use a while loop:

def commandA () :
    result = ""
    while (result != "OMG its a valid selection")
       # perhaps put a 0.1s sleep in here
       result = commandB()
    do_another_command()

---

I noticed that

selection in your code isn't actually being given a value (at least not in the code you've given us), is it not supposed to be:

selection = maya.mel.eval("scriptjob "making a valid selection" -type polygon")

---

Also, is there a reason why you're calling commandB recursively? This could end up using unnecessary resources, especially if someone repeatedly makes the wrong selection. How about this?

def commandA () :
    result = ""
    while (result != "polygon")
       # perhaps put a 0.1s sleep in here (depending on the behavior of the maya command)
       result = commandB()
    do_another_command()

def commandB () :
   # This command retrieves the selection
   selection = maya.mel.eval("scriptjob "making a valid selection" -type polygon")
   return selection 

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