[Python-3000] PEP3099 += 'Assignment will not become anoperation'
tjreedy at udel.edu
Thu May 3 10:17:15 CEST 2007
"Greg Ewing" <greg.ewing at canterbury.ac.nz> wrote in message
news:463981B2.6090704 at canterbury.ac.nz...
| Terry Reedy wrote:
| > and hence '=' will not become an operator and hence '=' will not become
| > overloadable.
| Actually, '=' *is* overloadable in most cases,
It is not overloadable in the sense I meant, and in the sense people
occasionally request, which is to have '=' be an *operation* that invokes a
special method such as __assign__, just as the '+' operation invokes
| you can arrange for a suitably customised object
| to be used as the namespace being assigned into.
| About the only case you can't hook is assignment
| to a local name in a function.
I mentioned purse classes in the appropriate place -- c.l.p.
I cannot think of any way to make plain assignment statements ('a =
object') at module scope do anything other than bind an object to a name in
the global namespace.
Back to my original point: people occasionally ask that assignment
statements become assignment expressions, as in C, by making '=' an
operation with an overloadable special method. Guido has consistently said
no. This came up again today. Since this is a much more frequent request
than some of the items already in 3099, I think it should be added their.
Terry Jan Reedy
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