Re: signals documentation question

On Tue, Oct 30, 2012 at 1:40 PM, Mike Dewhirst <miked@dewhirst.com.au> wrote:

The 1.5 docs say ...

Where should this code live?
You can put signal handling and registration code anywhere you like. However, you'll need to make sure that the module it's in gets imported early on so that the signal handling gets registered before any signals need to be sent. This makes your app's models.py a good place to put registration of signal handlers.

... and my question:

When models live in a models directory instead of models.py, should the signal handling and registration code go in __init__.py where the models are imported?

There isn't really going to be a *good* answer for this, due to the general problems that exist with having  reliable, one-time-import-only startup routine. __init__.py is probably as good a place as any (modulo the usual arguments against putting code in __init__.py); the actual files providing the models would be another candidate location. 

However, this will all depend on the exact import patterns that exist in your own code. Even putting signals in a 'normal' models.py file can be problematic, depending on how you import your code. Essentially -- suck it and see; if you start seeing multiple signals being fired unexpectedly, investigate the ways your code is being imported, and either simplify those imports, or find another location to put the registrations.

As an aside -- this is one of the reasons we need help landing the #3591 app-refactor branch. One of the side effects of this branch will be a reliable startup mechanism for apps, which will provide somewhere you can put code (like signal registrations) that needs to be invoked exactly once at the startup of the stack.

Yours,

Russ Magee %-)

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