[Numpy-discussion] Ufuncs and flexible types, CAPI

Samuel John scipy@samueljohn...
Tue Jan 10 10:29:04 CST 2012

[sorry for duplicate - I used the wrong mail address]

I am afraid, I didn't quite get the question.
What is the scenario? What is the benefit that would weight out the performance hit of checking whether there is a callback or not. This has to be evaluated quite a lot.

Oh well ... and 1.3.0 is pretty old :-)


On 31.12.2011, at 07:48, Val Kalatsky wrote:

> Hi folks, 
> First post, may not follow the standards, please bear with me. 
> Need to define a ufunc that takes care of various type. 
> Fixed - no problem, userdef - no problem, flexible - problem. 
> It appears that the standard ufunc loop does not provide means to 
> deliver the size of variable size items. 
> Questions and suggestions:
> 1) Please no laughing: I have to code for NumPy 1.3.0. 
> Perhaps this issue has been resolved, then the discussion becomes moot. 
> If so please direct me to the right link. 
> 2) A reasonable approach here would be to use callbacks and to give the user (read programmer) 
> a chance to intervene at least twice: OnInit and OnFail (OnFinish may not be unreasonable as well). 
> OnInit: before starting the type resolution the user is given a chance to do something (e.g. check for 
> that pesky type and take control then return a flag indicating a stop) before the resolution starts
> OnFail: the resolution took place and did not succeed, the user is given a chance to fix it. 
> In most of the case these callbacks are NULLs. 
> I could patch numpy with a generic method that does it, but it's a shame not to use the good ufunc machine. 
> Thanks for tips and suggestions.
> Val Kalatsky
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