Should I take your e-mail only for 'var'? What about PolynomialRing?
Should we just allow the creation of such variable name but add a
warning in the inject_variables function?
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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