According to the Poser 11 PoserPython manual AskMenu returns a StringType.

This is correct, EXCEPT if you click the 'Cancel' button on the dialogue, when it returns a NoneType.

To catch that I found I had to cast (if that's the correct Pythonspeak) the return value as a string, which appears to convert NoneType to "None".

        ...
        action = ""
        while action == "":
            # According to the Poser 11 PoserPython manual AskMenu() returns .
            # If you select an option from the list and hit 'OK' it returns that option as a string.
            # If you hit 'OK' with 'None' selected it returns "".
            # BUT if you hit 'Cancel' it actually returns , so I have to cast the return value as a string just in case (it will be "None" for )
            action = poser.DialogSimple.AskMenu("Multiple 'SmartPlusData.txt' files found","Select which to use:",foundfilelist)
        locatedfile = str(action)
        ...

I don't recall having this problem with PP2014, although it's possible I never tested clicking the Cancel button from an AskMenu

(N.B. this darn forum s**tware removed anything between (and including) less-than and greater-than symbols, so the types in my code extract disappeared, despite being within a triple backtick block )`

you could try

def askmenu( foundfilelist ) :
    return poser.DialogSimple.AskMenu("Multiple 'SmartPlusData.txt' files found","Select which to use:",foundfilelist) else False

if askmenu( filelist ): 
    do something

***UNTESTED***

or an alternative

import wx
class dialogs:
    def choose( self, title = "", prompt = "", OptionList = [], parent = None ):

        dialog = wx.SingleChoiceDialog( parent, prompt, title, OptionList )
        
        if not OptionList == []:

            return dialog.GetStringSelection() if dialog.ShowModal() == wx.ID_OK else False

you can choose to return anything if the cancel button is pressed ,

e.g.

return dialog.GetStringSelection() if dialog.ShowModal() == wx.ID_OK else "NOTHING"

Yes indeed, there are many ways to get round it, but you shouldn't need to as it's supposed to return a StringType.

Hence 'bug'.

This looks like sloppy coding of AskMenu() to me - trust me, I'm an expert on sloppy coding... ;o)

However, I like your alternative workarounds better than my own, and this seems to get round the bug nicely for me:

       action = ""
        while action == "":
            action = poser.DialogSimple.AskMenu("Multiple 'SmartPlusData.txt' files found","Select which to use:",foundfilelist)
            # Handle NoneType return value if Cancel button pressed
            if action:
                locatedfile = action
            else:
               locatedfile = "CANCEL"
            print "TEST RESULT = "+locatedfile

P.S. I don't use wxPython - far too complicated for my decaying brain ! So I'm stuck with PoserPython's built in dialogues

Returning None is the correct Python way if nothing is selected (canceled). Returning nothing is different than returning an empty string.

result = poser.DialogSimple.AskMenu(...)
if result:
   do_something()
else:
    forget_it()

In Python None is assumed as False.

for item in emptylist or listwithcontent:
    print(item_from_listwithcontent)

In that case it's probably not a bug then, just my lack of understanding of Python :)

So AskMenu() returns nothing (NoneType) if you click 'Cancel', but returns an empty/null string (StringType, "") if you click 'OK' with the AskMenu dialogue's default 'None' option, as shown below.

Thanks - that makes some sort of sense now.

It's also worth noting that BOTH None and '' (empty string) evaluate to False in a boolean expression. That provides a simple way to distinguish between a useful returned string to be parsed (any non-empty string will evaluate as True) and a non-selection ('' OK) or cancellation (None). Python design has its own logic, and it takes some getting used to when coming from other languages.

Similarly with lots of other Poser Python API methods which can return None instead of an empty list. As in adp's second example, if a method could return None instead of an empty list, make use of None evaluating as False, and iterate over a list conditional like:

for item in ListMethodThatMayReturnNone() or []: # The " or []" CAN be iterated over without error, while None cannot
    pass