Re: [libvirt] Python binding APIs strict or loose
On 04/20/2012 04:23 AM, Guannan Ren wrote:
Hi
There is a question. we need strict python binding API
or loose one.
For example:
The setSchedulerParameters(), it accepts one of
parameters: 'vcpu_quota'
In C its type is of 'long long', then we need a
conversion from PyInt/PyLong
to 'long long' by using cpython function
'PyLong_AsLongLong'.
The problem is when the user python pass in a value of
type Pyfloat instead
of PyInt/PyLong, the cpython function drops the fraction
part of the value
automatically, Is it what we want or we need to add a
type checking to ensure that
the type of value passed in is PyInt/PyLong, otherwise,
we raise an exception.
Or a third option - if it is not PyLong, but is a floating point, then
validate that conversion from floating point to integer and back does
not change the value (that is, there was no fractional value to begin with).
I know C would just truncate unconditionally, but I don't know enough
python coding conventions to know if python programmers expect the same
behavior as C, or if they expect something else. But I do know that
whatever we pick should be consistent - our current approach of
accepting but truncating fractions for int while rejecting fractions for
long long is not consistent.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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