I have a Python add-in that includes an extension class. The only purpose of this extension is for some buttons in the add-in to be automatically enabled/disabled depending on if there are relevant layers in the current MXD's table on contents (by using the extension's itemAdded() and itemDeleted() functions).

Therefore I need this extension to be loaded automatically AND enabled when this add-in is installed.

In the config.xml, I have autoLoad="true". In the Python class, the __init__ function for the extension class includes:

self.enabled = True

I thought this should be enough for it to work as I wanted.

However, when I install the add-in and re-launch ArcMap, the extensions dialog shows the extension but NOT checked.

Now, I have found that if I run something like:

myExtension.enabled = True

Within the __init__ method of some other toolbar class (eg, one of the buttons, NOT the extension class), then the extension IS CHECKED in the extensions dialog when ArcMap is re-launched! However, it doesn't actually work - it's functions are not called. But, if I then quit ArcMap and restart ArcMap, the extension is both checked in the dialogue AND fully functional (presumably because it remained enabled from the previous run of ArcMap).

So I can get the desired behaviour ONLY if I do ALL of the following ODD things:

  • enable the extension in the class of some other add-in button (NOT just in the extension class itself)
  • launch ArcMap
  • quit ArcMap
  • launch ArcMap

After that it works fine on subsequent launches of ArcMap.

Is it possible to get a Python add-in extension to automatically load and be enabled by default when the add-in is installed by any other means, and to have it work the first time ArcMap is launched after the add-in is installed?

Ie, is there a correct way to get an extension to be fully functional immediately after an add-in is installed (and ArcMap re-launched once) without any other manual interaction from the user? Or is this behaviour simply not supported?

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