And
sage: var('_')
_
On 10/05/15 22:38, Vincent Delecroix wrote:
> More subtle issue that isn't detected in the symbolic ring
>
> sage: var('None')
> None
> sage: parent(None)
> <type 'NoneType'>
>
> On 10/05/15 22:26, Vincent Delecroix 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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