python style: inline function that needs no inlining?

I'mm writing gtk code. I often have short callbacks that don't need to be closures, as they are passed all the parameters they need. For example, I have this in a l开发者_开发技巧oop when creating some gtk.TreeViewColumns:

def widthChanged(MAINCOL, SPEC, SUBCOL, expandable):
    if expandable: return
    w = MAINCOL.get_width()
    SUBCOL.set_fixed_width(w)

cl.connect("notify::width", widthChanged, pnlcl, expand)

This is probably inefficient, since the function is being created on every iteration of the loop (side-question: is it actually, or is it optimized?). However, I feel like if I moved all these one-liners to the top level, the code would be more confusing. Any opinions?

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Go with whatever style is most readable. Don't worry about speed unless your code profiling tools have told you that the area is a hotspot.