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On Thu, Oct 8, 2009 at 1:42 AM, Terry Reedy <> wrote:
> Hans Mulder wrote:
>
>> Errrhm, no. *He is not deleting the PyQt4 module from sys.modules;
>> he's only deleting the name QtGui from his own namespace. *Next
>> time Python comes across
>>
>> * *from PyQt4 import QtGui
>>
>> , it finds that the module PyQt4 already exists in sys.modules, so
>> Python does not have to load the module again. *All it has to do is
>> bind name QtGui in the importing module to the class with the same
>> name in the PyQt4 module. *That does not take many cycles.
>
> I recently discovered that when IDLE restarts (as when one runs a file from
> an edit window), it clears the global namespace but does not clear
> sys.modules. Hence re-running a script that does time-consuming imports is
> much faster, as only the global name binding is done after the first run.

Is that with or without '-n'?

Simon Forman wrote:
> On Thu, Oct 8, 2009 at 1:42 AM, Terry Reedy <> wrote:
>> Hans Mulder wrote:
>>
>>> Errrhm, no. He is not deleting the PyQt4 module from sys.modules;
>>> he's only deleting the name QtGui from his own namespace. Next
>>> time Python comes across
>>>
>>> from PyQt4 import QtGui
>>>
>>> , it finds that the module PyQt4 already exists in sys.modules, so
>>> Python does not have to load the module again. All it has to do is
>>> bind name QtGui in the importing module to the class with the same
>>> name in the PyQt4 module. That does not take many cycles.
>> I recently discovered that when IDLE restarts (as when one runs a file from
>> an edit window), it clears the global namespace but does not clear
>> sys.modules. Hence re-running a script that does time-consuming imports is
>> much faster, as only the global name binding is done after the first run.
>
> Is that with or without '-n'?

The Windows start menu IDLE entry, which I gather is without -n, though
the property sheet does not actually give the command-line equivalent.

Terry Reedy wrote:
> Hans Mulder wrote:
>
>> Errrhm, no. He is not deleting the PyQt4 module from sys.modules;
>> he's only deleting the name QtGui from his own namespace. Next
>> time Python comes across
>>
>> from PyQt4 import QtGui
>>
>> , it finds that the module PyQt4 already exists in sys.modules, so
>> Python does not have to load the module again. All it has to do is
>> bind name QtGui in the importing module to the class with the same
>> name in the PyQt4 module. That does not take many cycles.
>
> I recently discovered that when IDLE restarts (as when one runs a file
> from an edit window), it clears the global namespace but does not clear
> sys.modules. Hence re-running a script that does time-consuming imports
> is much faster, as only the global name binding is done after the first
> run.

Whoops, on rechecking, above does not seem to be true. The faster rerun
time I was seeing was due to some other cause. Sorry for the noise.