Open mxd with python add-in?

[TrilliumLevine1]

This seems like it should be easy, but for some reason I can't figure it out.  Is there a way to implement a python add-in that runs on Arcmap startup that opens a specific mxd, as opposed to an empty one?  I know you can do lots of different things on startup with addins, but I haven't been able to find anything at all on simply running one that opens a specific mxd.  Any feedback would be appreciated!

[TrilliumLevine1]

this is what i've tried so far (as an application extension addin), but it's not working.  I also tried it without the open._doc_ bit:

import arcpy
import pythonaddins
import os

class Verbandsgebiet(object):
    """Implementation for Verbandsgebiet_addin.add (Extension)"""
    def __init__(self):
        # For performance considerations, please remove all unused methods in this class.
        self.enabled = True

    def startup(self):
        mxd = arcpy.mapping.MapDocument(r"E:\Programme\ArcGIS\Desktop 10.2\Templates\mymxd.mxd")
        open.__doc__(mxd)
return

[ShaunWalbridge]

The responses in this thread will be useful. You can't directly modify the current MXD, but if you're OK with opening a new session, you can do something like:

os.startfile(mxd_path)

If you do this, you won't need to use the arcpy.mapping call, just point it at the actual path of your MXD file.

[TrilliumLevine1]

Thanks Shaun, I'll check that thread out and see what shakes out...

[TrilliumLevine1]

ok, so i tried the os.startfile(mxd_path) bit within the extension add-in, and the result is that two instances of Arc always open -- a blank mxd and then mxd_path.  Another problem is that multiple instances of mxd_path open, seemingly without end.  I actually have to shut the machine down to get it to stop opening instances of mxd_path.

my add-in code currently looks like this:

import arcpy
import pythonaddins
import os

class ExtensionClass1(object):
    """Implementation for mxd_addin.extension2 (Extension)"""
    def __init__(self):
        # For performance considerations, please remove all unused methods in this class.
        self.enabled = True
    def startup(self):
        os.startfile('mxd_path)