[Grace-core] Undefined Variables

[Marco Servetto]

Hi Andrew, the more the time pass, the more you get closer to my ideas :P

I would like to remind you that any non capturable error is a Bad Idea
for the same reasons. Do we have any other non capturable stuff?

On 25 February 2015 at 23:15, Kim Bruce <kim at cs.pomona.edu> wrote:
> It sounds like one of those things that will be available, but not made prominent, that is mainly there for tools to use.  (Perhaps we could even issue a warning in any program that uses it.)  At any rate, while I would discourage students from using it, it seems useful for building tools.  It's OK to me tao have it raise an exception.
>
> Kim
>
>
>
>> On Feb 25, 2015, at 1:37 PM, Michael Homer <mwh at ecs.vuw.ac.nz> wrote:
>>
>> On Thu, Feb 26, 2015 at 8:37 AM, Andrew P. Black <black at cs.pdx.edu> wrote:
>>> I woke up in the middle of the night on Monday realizing what a Bad Idea it
>>> was to make the error that occurs when one accesses an undefined variable
>>> “uncatchable”.
>>>
>>> We can catch other kinds of programming error, such as requesting a method
>>> that does not exist, or indexing an array outside of its bounds.  Why should
>>> this one be different?
>> The motivation at the time was to prevent people using it as a bottom
>> or signal value (which was the kick you were all on then). Being able
>> to trap the error was regarded as a back door to null.
>> -Michael
>>
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