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?

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.