[Python-Dev] Adding a conditional expression in Py3.0 (original) (raw)

Michael Urman murman at gmail.com
Sat Sep 24 07:40:39 CEST 2005

On 9/23/05, Nick Coghlan <ncoghlan at gmail.com> wrote:

But I think there's a difference in kind here - to fix Raymond's example required a fundamental change to the structure of the line, none of which looked as clean as the original. There is no way to get the and/or construct to gracefully handle the case where the desired result in the 'true' case might itself be false: either you change to using an if statement, or you use a workaround like the ugly singleton-list approach.

That is, the following is fundamentally broken for pure imaginary numbers: return isinstance(z, ComplexType) and z.real or z

It's hard to say whether this fixes Raymond's example when the goal wasn't clearly stated, but I find a non ternary option

lambda z: complex(z).real

more readable than any of the variants proposed so far. The obvious downsides are that it can raise a ValueError, and turns integers into floats. But if the input list is all numeric, it has clean results.

-- Michael Urman

More information about the Python-Dev mailing list