User:Sybren/SfA/operators

Your Own Operator

• So far: only snippets of code.
• Not really user friendly.
• Menu items, buttons, panels.
• For that: operators.

What is operator

• Glue between some code and hotkeys, menus, buttons.
• F3 to search for them.
• Operator provides identifier, label, and tooltip.
• Checks the context.
• Multiple modes
  • execute: simplest, single-shot. This happens when you call from Python.
  • invoke: when called from UI, can do some extra things and then calls execute()
  • modal: needs to be set up from invoke, allows running for longer period (file browsers, exporters, network communication). Makes the operator receive events (keyboard presses, mouse moves, timers).

Making an operator

• Group some information together:
  • Identifier (the thing after bpy.ops)
  • Label
  • Tooltip
  • The code itself
• Make a class
  • Inheritance: parent-child structure
  • Just like in real life: child answers what it can, otherwise defers to parent: "Moooooom!"
  • The practical side: we can add what we need, and leave out what we don't.
• Put the code into a function.
• Add an execute method to call our function.
• Register the operator.
• Use F3 to find & run it.

Passing Parameters & the Redo Panel

• Property: Number of monkeys
• Set bl_options = {'REGISTER', 'UNDO'}
• Use the redo panel

Limiting the Context

• Show example of 'autocomplete' operator in 3D view and Python console.
• Done by poll class method returning True or False
• Make our operator only run when in 3D view:

@classmethod
def poll(cls, context) -> bool:
    return context.area.type == 'CONSOLE' and context.mode == 'OBJECT'