Stream: helpdesk (published)

Topic: PythonCall: Handling possibly None value

Jesper Stemann Andersen (Apr 18 2023 at 17:02):

How to handle a Py value which can be None (with PythonCall)?

The following seems quite verbose (and it fails if x is an ndarray)

using PythonCall

function handle_optional_value(x::Py)
    if pyconvert(Bool, x == pybuiltins.None)
        return nothing
    end
    # something else
end

Santtu (Apr 19 2023 at 04:20):

I do not think that is verbose at all. There is a difference between being succinct and being so truncated as to be illegible. There seems to be an undue respect towards the latter, in many cases.

Santtu (Apr 19 2023 at 04:28):

Also, you should probably be using the pyis function from the PythonCall library instead of ==, to compare x to None (link).

jar (Apr 19 2023 at 05:03):

function then(f, x::Py)
    if pyconvert(Bool, x == pybuiltins.None)
        return nothing
    end
   f(x)
end

then(y) do x
   x + 1
end

Last updated: Oct 02 2023 at 04:34 UTC