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
>
--
You received this message because you are subscribed to the Google Groups
"sage-devel" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To post to this group, send email to sage-devel@googlegroups.com.
Visit this group at http://groups.google.com/group/sage-devel.
For more options, visit https://groups.google.com/d/optout.
