[Python-Dev] Equality on method objects

Adam Olsen rhamph at gmail.com
Mon Mar 10 17:20:14 CET 2008

On Mon, Mar 10, 2008 at 4:26 AM, Armin Rigo <arigo at tunes.org> wrote:
> Hi Phillip,
>  On Sun, Mar 09, 2008 at 07:05:12PM -0400, Phillip J. Eby wrote:
>  > I did not, however, need the equality of bound methods to be based on
>  > object value equality, just value identity.
>  >
>  > ...at least until recently, anyway.  I do have one library that wants
>  > to have equality-based comparison of im_self.  What I ended up doing
>  > is writing code that tests what the current Python interpreter is
>  > doing, and if necessary implements a special method type, just for
>  > purposes of working around the absence of im_self equality
>  > testing.  However, it's a pretty specialized case (...)
>  I found myself in exactly the same case: a pretty specialized example
>  where I wanted bound methods to use im_self equality rather than
>  identity, solved by writing my own bound-method-like object.  But that's
>  not really hard to do, and the general tendency (which matches my own
>  opinion too) seems to be that using im_self identity is less surprizing.
>  In general, "x.append" is interchangeable with "x.append" even if
>  "x.append is not x.append", so let's go for the least surprizing
>  behavior: "m1.im_self is m2.im_self and m1.im_func==m2.im_func".
>  Objection?


Adam Olsen, aka Rhamphoryncus

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