I think python only has 3 unary operations, + - and ~ and only + and - can also be binary operations.
unary + has less uses, since it normally just passes its argument, if valid, unchanged, but can be used to validate that its argument has the right type. I am not sure if a type could define its own unary+ to do something special, but I thought it could. On 4/2/21 11:19 AM, John wrote: > True. It gets ambiguous when doing n*(-(x + y)) i.e. n x y + - * > (fail). The simplest solution is n 0 x y + - * > > I can't actually think of any other unary operators. > > On Fri, Apr 2, 2021 at 10:54 AM Richard Damon <rich...@damon-family.org> > wrote: >> One problem with trying to mix RPN with in-fix is that some operators, >> like - can be either a unary or binary operation in the in-fix >> notations, distinguished by context. In RPN you have lost that context. >> >> is x y - - the same as -(x-y) or is it x-(-y) ? or is it waiting for >> another operator and be x ?? (-(-y)) or is it expecting a previous >> operand and is ?? - (x-y) >> >> (same with +) >> >> Typical RPN systems get around this by having unary - be a different >> symbol/key that binary - >> >> -- >> Richard Damon >> >> _______________________________________________ >> 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/LX5T33N6IU6IMDKXU4KQMA2RP6U627CG/ >> Code of Conduct: http://python.org/psf/codeofconduct/ -- Richard Damon _______________________________________________ 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/NCAY6SMGQJBRID7AYR6JWOTJGV7CZDGW/ Code of Conduct: http://python.org/psf/codeofconduct/
