attributes' default value not saved in scene

[benblo]

If I create an attribute with a default value, but don't change it, the value is lost after saving & reloading the scene.
I don't know if it's by design or not, but I do see the default value I set appear correctly in the attribute editor, so it's extremely confusing to have the attribute be wiped after reloading the scene.

Here's an all-in-one example:

• create a new scene, add a sphere
• add 3 attributes to the sphere, with default values
• change the value of the first one
• assign the second one's to the same value
• don't touch the third one
• save & reload the scene: you'll see the first attribute's value is "1a", but the second & third are empty!

# create new scene, no prompt
cmds.file(new=True, force=True) # new file, no prompt

sphere = cmdx.encode(cmds.sphere()[0])
sphere.add_attr(cmdx.String("string_1", default="1"))
sphere.add_attr(cmdx.String("string_2", default="2"))
sphere.add_attr(cmdx.String("string_3", default="3"))
sphere["string_1"] = "1a"  # will be saved
sphere["string_2"] = "2"   # will be lost!
                           # string_3 will also be lost!

# save & reload scene, no prompt
scene_path = "test.ma"
cmds.file(rename=scene_path)
cmds.file(save=True, type="mayaAscii")
cmds.file(scene_path, open=True, force=True)

[wougzy]

That's probably because Maya doesn't support default values for non numeric types. You can't even do that manually.

String.default() should be removed to avoid confusion (or at least removed at addAttr)

[mottosso]

Strange that it assigns the value at all. :/

We could remove it, but I think we should handle it instead. No reason this shouldn't work other than a Maya API limitation, and we can just regularly assign it post-creation to keep all attributes uniform and working as expected.

Anyone interested in tackling this?

[benblo]

I have a workaround already, it’s ugly but I can kick a PR tomorrow-ish.
What’s weird is the OM API accepts the default for TypedAttr, it’s even custom handled by cmdx to convert the python str to MObj (plus reassigning the same value doesn’t trigger a dirty so the default is tracked)... so it really looks like it should work, it’s just not saved in scene.