How to use 'is' keyword in GhPy?

Scripting
#1

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That’s assigned to a variable obj
when I type obj is Rhino.DocObjects.ExtrusionObject, I’m expecting that it would evaluate to True. But it’s not. I think I’m using the is keyword wrong. Any help please?

#2

Hi @Will_Wang,

How about this:

import clr
extrusion_obj = clr.Convert(obj, Rhino.DocObjects.ExtrusionObject)
if extrusion_obj:
    # todo...

– Dale

#3

What about

if isinstance(obj,Rhino.DocObjects.ExtrusionObject):
    #do something
1 Like
#4

what makes the difference? looks like isinstance() is a built-in method. why wouldn’t is work?

#5

clr.Convert(obj,Rhino.DocObjects.ExtrusionObject) would throw an error if the obj isn’t that type, therefore stopping my script, which is essentially a type filter so a lot of non-type

#6

As far as I know (my programming knowledge is not incredible) ‘is’ means that the argument is exactly the same object as the target - this from StackOverflow:

The operators is and is not test for object identity: x is y is true if and only if x and y are the same object.

In this case your object is an instance of an extrusion object, not the equivalent of the class itself…

At least that’s the way I understood it, I just picked up ‘isinstance’ on the fly from looking at other examples…

#7

Thanks! Very clear.

#8

type(obj) is thetypeyoucomparewith

1 Like