Steven D'Aprano wrote: > On Thu, Oct 17, 2019 at 08:19:13AM -0000, Steve Jorgensen wrote: > > Why the need for strictness of type for the operator? > > I get that it's > > analogous with the behavior for list, but I guess I'm also not sure > > why that should be strict. > > (1) Follow the precedent of existing operators. > (2) It is easier to relax restrictions later, than to add restrictions > if the original behaviour turned out to be a mistake. So it is (usually) > better to begin with the most conservative thing that will work and > gradually allow more if and when needed. > (It is relatively easy to add functionality to the language, but very > difficult to take it away.) > > Also, why was subtraction dropped? It seems to me the > > ability to > > subtract an iterable of keys makes a lot of sense — or maybe that > > should be a separate PEP? > > In the initial discussion, the subtraction operator got very little > attention. It isn't really fair to sneak in a second operator as part of > a controversial proposal like this one. > If someone wishes to re-propose the subtraction operator, or the full > suite of set-like operations (intersection, difference, symmetric > difference, union) they are free to do so, either as an adjunct to, > or a competitor of, this PEP.
Thanks. Those explanations make sense to me. :) _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/JNKQ6DB56MA6TCTYPLBK4LOGKRKP4R5U/ Code of Conduct: http://python.org/psf/codeofconduct/
