On Thu, Jun 18, 2009 at 12:29 AM, Robert
Bradshaw<rober...@math.washington.edu> wrote:
>
> On Jun 17, 2009, at 9:21 AM, William Stein wrote:
>
>> 2009/6/17 Robert Bradshaw <rober...@math.washington.edu>:
>>>
>>> On Jun 17, 2009, at 3:05 AM, Utpal Sarkar wrote:
>>>
>>>> Thanks for the replies.
>>>> I noticed something funny: if you call x = var("X") in some
>>>> scope, it
>>>> is X that is injected into the global scope, not x. In fact I
>>>> thought
>>>> that the argument was merely a print name.
>>>
>>> var("X") is what makes the variable, there's nothing special about
>>> assignment. For example, if I wrote
>>>
>>> sage: x = var("X") + 1
>>>
>>> then x would have the value X + 1, and as a side effect, X would be
>>> injected into the global scope. This seems like a surprising artifact
>>> to many people, and is certainly not like anything Python does. Was
>>> there a strong justification for doing this?
>>
>> If I remember correctly:
>>
>> 1. The symbolic calculus code is not aimed at experience Python
>> programmers or users.
>>
>> 2. It is very nice for var('x,y,z,theta') to work, and to not require
>> the user to type:
>> x,y,z,theta = var('x,y,z,theta')
>>
>> 3. Having var at all is a compromise -- many symbolic calculus users
>> would prefer for undefined vars to just "magically" be defined, as is
>> done in Mathematica, Maple, Maxima, Axiom (?), etc.
>
> That's enough justification for me. I'm still in favor of an optional
> "global" keyword to the var function that was brought up earlier.in sympy we use symbols() for just returning the symbols and var() that calls (and returns) symbols *and* injects them to the global space. O. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
