[Numpy-discussion] Fwd: GPU Numpy

[Robert Kern]

On Thu, Aug 6, 2009 at 19:00, Fernando Perez<fperez.net at gmail.com> wrote:
> On Thu, Aug 6, 2009 at 1:57 PM, Sturla Molden<sturla at molden.no> wrote:
>> In order to reduce the effect of immutable arrays, we could introduce a
>> context-manager. Inside the with statement, all arrays would be
>> immutable. Second, the __exit__ method could trigger the code generator
>> and do all the evaluation. So we would get something like this:
>>
>>    # normal numpy here
>>
>>    with numpy.accelerator():
>>
>>        # arrays become immutable
>>        # lazy evaluation
>>
>>        # code generation and evaluation on exit
>>
>>    # normal numpy continues here
>>
>>
>> Thus, here is my plan:
>>
>> 1. a special context-manager class
>> 2. immutable arrays inside with statement
>> 3. lazy evaluation: expressions build up a parse tree
>> 4. dynamic code generation
>> 5. evaluation on exit
>
> You will face one issue here: unless you raise a special exception
> inside the with block, the python interpreter will unconditionally
> execute that code without your control.  I had a long talk about this
> with Alex Martelli last year at scipy, where I pitched the idea of
> allowing context managers to have an optional third method,
> __execute__, which would get the code block in the with statement for
> execution.  He was fairly pessimistic about the possibility of this
> making its way into python, mostly (if I recall correctly) because of
> scoping issues: the with statement does not introduce a new scope, so
> you'd need to pass to this method the code plus the locals/globals of
> the entire enclosing scope, which felt messy.

Sometimes, I fantasize about writing a python4ply grammar that
repurposes the `` quotes to provide expression literals and ``` ```
triple quotes for multiline statement literals. They would be literals
for _ast abstract syntax trees.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
  -- Umberto Eco