A startup puzzle

[Peter Otten]

Edward K. Ream wrote:

> I've just about convinced myself there is no good, clean solution to the
> following puzzle.  I wonder if you agree.

If I understand you correctly, you do

leoGlobals.py
_app=None
def app():
    global _app
    if not _app:
        # other code
        _app = Application()
    return _app

leoMain.py
from leoGlobals import *
app = app()
app.mainLoop()

leoOther.py
from leoGlobals import *

app().doSomething()


Does it happen that your program runs without ever creating the Application
instance? If not, there's no point in lazy creation:

leoGlobals.py
app=None
def createApp():
    global app
    assert not app
    app = Application()

leoMain.py
from leoGlobals import *
createApp()
app.mainLoop()

leoOther.py
from leoGlobals import *
# this works iff you can ensure that leoMain.py is the 
# only "entry point" to your application
app.doSomething()


If I missed something, it would probably help if you post similar code
fragments to show where the above scheme would fail to work.

Peter