Comment about 'self._providers = [k(self) for k in kprovcls]' in backend/openmp/base.py

[Kiny Wan]

Hi Freddie and everyone,

        The more you learn, the more problems you encounter! Today, I want to discuss about a python operation in backend/openmp/base.py, which is very advanced. The code is shown as follow:

# Instantiate mandatory kernel provider classes
kprovcls = [provider.OpenMPPointwiseKernelProvider,
blasext.OpenMPBlasExtKernels,
packing.OpenMPPackingKernels,
gimmik.OpenMPGiMMiKKernels]
self._providers = [k(self) for k in kprovcls]

        The 'self' is brought into the class 'k'. Using print function, I found that k(self) represents object and k denotes class.  I am wondering what impact this will have? 

print(provider.OpenMPPointwiseKernelProvider(self))

<pyfr.backends.openmp.provider.OpenMPPointwiseKernelProvider object at 0x7f5551a03b70>

print(provider.OpenMPPointwiseKernelProvider)

<class 'pyfr.backends.openmp.provider.OpenMPPointwiseKernelProvider'>

[Freddie Witherden]

Hi,

Here k corresponds to a class. Hence k(self) corresponds to creating an
instance of the class referred to by k passing self as the first
parameter, which results in an object.

Regards, Freddie.

On 07/07/2020 06:33, Kiny Wan wrote:
> Hi Freddie and everyone,
>         The more you learn, the more problems you encounter! Today, I
> want to discuss about a python operation in backend/openmp/base.py,
> which is very advanced. The code is shown as follow:
>
> # Instantiate mandatory kernel provider classes
> kprovcls = [provider.OpenMPPointwiseKernelProvider,
> blasext.OpenMPBlasExtKernels,
> packing.OpenMPPackingKernels,
> gimmik.OpenMPGiMMiKKernels]

> self._providers = [k(*self*) for k in kprovcls]
>
>         The '*self*' is brought into the class 'k'.
> Using print function, I found that k(*self*) represents object and k
> denotes class.  *I am wondering what impact this will have? *

>
> print(provider.OpenMPPointwiseKernelProvider(self))
> <pyfr.backends.openmp.provider.OpenMPPointwiseKernelProvider object at
> 0x7f5551a03b70>
> print(provider.OpenMPPointwiseKernelProvider)
> <class 'pyfr.backends.openmp.provider.OpenMPPointwiseKernelProvider'>
>

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[Kiny Wan]

Thank you very much. The 'self._providers' is passed to 'backend', which is used to register pointwise kernels. The backend.pointwise.register() in elements.py will get errors when using k instead of k(self).