On Sunday, May 10, 2015 at 11:02:05 PM UTC+2, vdelecroix wrote:
>
> Should we just allow the creation of such variable name but add a
> warning in the inject_variables function?
>
IMHO yes, both var and R.<x,y> = QQ[] and anything else that injects
globals should fail at the injection only. If you don't inject then any
identifier should be allowed as variable label.
>
> I am worried of making impossible the use of 'as' or 'or' as variable
> names. The following looks like a plausible Sage usage
>
> sage: alpha ='abcdefghijklmnopqrstuvwxyz'
> sage: PolynomialRing(ZZ, [i+j for i in alpha for j in alpha])
>
> On 10/05/15 22:54, Volker Braun wrote:
> > The checking in symbolic rings should be moved to sage.repl.user_globals
> > and hooked into set_global.
> >
> > As for part 2, "None" is not a reserved keyword in Python2 so its in
> > principle perfectly legal to use as identifier. Though it was later on
> > specifically disallowed to assign to None, but assignment to True/False
> is
> > still possible. This is fixed in Python3 where None, True, False become
> > keywords.
> >
> > We should probably exclude Python builtin names for that as well, i.e.
> > dir(__builtin__), not because its not legal but because its mighty
> > confusing to redefine int/str/id/all/...
> >
> > On Sunday, May 10, 2015 at 10:26:25 PM UTC+2, vdelecroix wrote:
> >>
> >> Hello,
> >>
> >> What should we do with variable names like 'or', 'and', ... This does
> >> not break uniformly
> >>
> >> The symbolic ring refuses the creation of such variable
> >> {{{
> >> sage: SR.var('and')
> >> Traceback (most recent call last):
> >> ...
> >> ValueError: The name "and" is not a valid Python identifier.
> >> }}}
> >>
> >> whereas polynomial rings silently fail
> >> {{{
> >> sage: R = PolynomialRing(QQ, ('and', 'or'))
> >> sage: R.inject_variables()
> >> Defining and, or
> >> sage: and
> >> ...
> >> SyntaxError: invalid syntax
> >> sage: 'and' in globals()
> >> True
> >> }}}
> >>
> >> Vincent
> >>
> >
>
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