How to create a lattice and link all objects to it procedurally?

Question

I've been trying to do that but have got some problems:

1. I was not able to retrieve the reference to a recently created object with bpy.ops.object.add().
   I had to use bpy.ops.lattice.select_all(), but that sounds inelegant.

2. While I was able to create a lattice for each object with bpy.ops.object.modifier_add(type='LATTICE'), I was not able to link it - mostly because the command to link a lattice modifier to the lattice object won't show on the info window. (Also, this needs the object to be selected...)

What is the proper way to do it?

Answer 1

The proper way is to not use operators:

import bpy

scene = bpy.context.scene

lattice = bpy.data.lattices.new("Lattice")
lattice_ob = bpy.data.objects.new("Lattice", lattice)
lattice_ob.scale = (5, 5, 5)

for ob in scene.objects:
    if ob.type == 'MESH':
        mod = ob.modifiers.new("Lattice", 'LATTICE')
        mod.object = lattice_ob

scene.objects.link(lattice_ob)
scene.update()

The .new() methods return object references to be used for subsequent method calls and property assignments in contrast to operators, which run isolated and only return a status (e.g. {'FINISHED'}). Some methods also take objects (the second parameter of objects.new()), whereas operators don't support objects/pointers, but only references by name (StringProperty).

//update: For Blender 2.8 and above, I believe you would do it like this:

import bpy

collection = bpy.context.collection

lattice = bpy.data.lattices.new("Lattice")
lattice_ob = bpy.data.objects.new("Lattice", lattice)
lattice_ob.scale = (5, 5, 5)

for ob in collection.objects:
    if ob.type == 'MESH':
        mod = ob.modifiers.new("Lattice", 'LATTICE')
        mod.object = lattice_ob

collection.objects.link(lattice_ob)