On Wed, Jun 5, 2019 at 12:52 AM Greg Ewing <greg.ew...@canterbury.ac.nz> wrote: > > Yanghao Hua wrote: > > Did Guido say "user defined syntax" or "user defined operator"? > > ... for me defining new operator is different > > To my mind it's not that much different. A reader encountering an > unfamiliar operator is pretty much faced with a new piece of > syntax to learn. Its spelling gives little to no clue as to its > meaning, it precedence in relation to other operators is not > obvious, etc. > > > The way scala allows user to define new operator is > > really elegant, > > There are some differences between Python and Scala that present > practical difficulties here. Some kind of declaration would be > needed to define its arity, precedence and corresponding dunder > method. This is no problem in Scala because it analyses imported > code at compile time. But the Python compiler only sees the module > being compiled, so it has no ability to import these kinds of > declarations from another module.
My understood how scala achieves this is, whenenver it sees "taken1 token2 token3" kind of expression, it does token1.token2(token3). So it was assumed token2 is a method of token1 and it always takes one argument. With my very limited understanding of cpython internals (at least when I implement <==) it seems cpython is searching for an operator and then translates it into a method call on the objects, so what if instead of telling e.g. python to search __add__ method call, it should search int.+ (the "+" method call) instead? Not sure if this helps at all I believe there are tons of other problems too. This is definitely NOT an easy thing to add post-fact if not thought through from the very beginning. _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org %(web_page_url)slistinfo%(cgiext)s/%(_internal_name)s Code of Conduct: http://python.org/psf/codeofconduct/
