Truth Value Checking

Here is an example of how truth value checking works in this API.

Objects from this API are considered false when:

• The object is null
• The object is an empty array
• Special cases such as SoundItem and TexturePaletteEntry. These are considered null once they are removed from a SoundList or TexturePalette, respectively

Python Docs on Truth Value Checking

import Editor
import Vertex
import VertexArray

# Opening two documents, one new document, and one that doesn't exist
docExists = Editor.NewDocument()
nullDoc = Editor.OpenDocument( "nonExistentDoc.gls" )

# Will be True because the document object exists
if docExists:
    print( "Document exists." )

# Will be considered False since the object is null
if not nullDoc:
    print( 'Document does not exist' )

# Creating an empty VertexArray
vertexArray = VertexArray.VertexArray()

# Will be considered False because the array object is empty
if not vertexArray:
    print( 'The array is empty' )

# Adding a vertex to the array
vertex = Vertex.Vertex( 0, 0, 0 )
vertexArray.Insert( vertex )

# Will now be considered True because the array is not empty
if vertexArray:
    print( 'The array is not empty' )

# Retrieving the document's sound list and adding a sound to it
soundList = docExists.GetSoundList()
soundList.AddSound( "someSound.mp3" )
soundItem = soundList.GetSoundItem( 0 )

# The SoundItem exists as long as it's in the SoundList
if soundItem:
    print( 'This SoundItem exists' )

# Once the SoundItem is removed, it is considered null, and therefore false
soundList.RemoveSound( soundItem )
if not soundItem:
    print( 'This SoundItem no longer exists' )