On Sun, Nov 2, 2008 at 10:35 AM, Simon King <[EMAIL PROTECTED]> wrote:
>
> Hi!
>
> On Nov 2, 6:18 pm, "William Stein" <[EMAIL PROTECTED]> wrote:
>> >> People coming from a Mathematica background should not assume that
>> >> they know all there is to know about how to use a Computer Algebra
>> >> System, and instead, read the documentation.
>>
>> > This is so obnoxiously wrong, I just don't know where to start.
>>
>> What is wrong? That statement Justin made or that he made it at all?
>
> I think Justin's statement is true in the sense that people with a
> Mathematica, Maple, Magma or Sage background should not believe that
> the respective system is the philosopher's stone. It should be self-
> evident that changing from one system to another sometimes involves to
> look into a manual.
>
> On the other hand, the statement is partially wrong in the following
> sense: We should not *suppose* that a person changing from Mathematica
> to Sage will first thoroughly read the manual. I agree with Robert,
> who wrote that one should try to accomodate the people.
>
> I think Harald is right that a descriptive error message can be very
> helpful to a novice. The problem is that a very descriptive message
> would depend on the context, and making it context-sensitive would
> involve work. But it is (to some extent) doable!
>
> Example:
> -------------
> 1.
> sage: y
> ...
> NameError: name 'y' is not defined
>
> That's clear enough.
>
> 2.
> sage: sin(y)
> ...
> NameError: name 'y' is not defined
>
> That's the same message - but the context (calculus-function) makes it
> clear that the user wanted to make y a variable. Suggestion:
>
> 3.
> Context sensitivity could be obtained by catching and re-raising
> errors.
> Would it be possible that the calculus-functions catch any NameError
> and re-raise it with an extended error message? The following error
> message may be a better help to the people:
> sage: sin(y)
> ...
> NameError: name 'y' is not defined. If 'y' is intended to be a
> variable, please use var('y'). Type var? for help
The NameError is raised before the code is ever evaluated
by the sin function. It is a raised when the code is being
parsed by Python in the first place. So I don't know how
it would be possible to do what you suggest above.
William
--
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org
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