Existence of an attribute

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Marco Baccalaro asked Apr 10, '18 Marco Baccalaro commented Apr 10, '18

Existence of an attribute

I have this code that returns <no path>:

Object box = model().find("Tools/FlowItemBin/Box/Box");
treenode itemBehaviour = box.attrs.behaviour;
return itemBehaviour;

But this code returns "It exists":

Object box = model().find("Tools/FlowItemBin/Box/Box");
treenode itemBehaviour = box.attrs.behaviour;
if (itemBehaviour)
	return "It exists";
else
	return "It does not exist";

It returns "It does not exist" if I change the second row to:

treenode itemBehaviour = box.find(">behaviour");

Why does this happen? Is it because those are hashed nodes?

Software Version:

FlexSim 18.0.4

attributes objectexists object.attrs

attributeexistence.fsm (16.1 KiB)

Answer 1 · 2018-04-10T15:06:22Z

Matthew Gillespie answered Apr 10, '18 Marco Baccalaro commented Apr 10, '18

This is a bug that we'll be fixing soon, but the issue is that currently box.attrs.behaviour is exactly the same as calling behaviour(box). This, like all the old commands that return a treenode, will return saferef instead of returning a null treenode.

So currently, if you use box.attrs.behaviour, you need to treat it like an old command and use if(objectexists(itemBehaviour)).

You could also use box.attrs.find("behaviour").

We'll be fixing the attrs property so that it no longer returns saferef when the attribute doesn't exist.

· 1

Marco Baccalaro commented · Apr 10, 2018 at 03:20 PM

Good! Thanks for the detailed explanation.

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