Baking a series of textures with INVOKE_DEFAULT

Question

I'm trying to build a simple bake tool that will allow me to bake a set of objects. Everything works if I EXEC_DEFAULT the bake operator, but this doesn't give me a progress bar and completely freezes the UI.

Switching to INVOKE_DEFAULT causes a problem with async- the loop executes but only the first bake operation is performed.

The relevant code is here:

class BakeryOperation(bpy.types.Operator):
    bl_idname = "bakery.bake"
    bl_label = "Bake textures"

    def invoke(self, context, event):
        scn = context.scene
        materials = set()
        for o in scn.bake_objects:
            materials = materials.union(set(map(lambda x: (o.name, x.name), bpy.data.objects[o.name].data.materials)))

        for (name, material) in materials:
            bpy.data.materials[material].use_nodes = True
            node_tree = bpy.data.materials[material].node_tree
            found = False

            img_name = name+"_bake"
            for n in [n for n in node_tree.nodes if n.type == 'TEX_IMAGE']:
                found = False

                if n.image != None and n.image.name == img_name:
                    n.select = True
                    node_tree.nodes.active = n
                    found = True
                    break
            if not found:
                node = node_tree.nodes.new("ShaderNodeTexImage")
                node.select = True
                node_tree.nodes.active = node
                if img_name in bpy.data.images:
                    node.image = bpy.data.images[img_name]
                else:
                    node.image = bpy.data.images.new(name + "_bake", 512, 512)

            img = bpy.data.images[img_name]

            bpy.ops.object.select_all("EXEC_DEFAULT", action="DESELECT")
            bpy.ops.object.select_pattern(pattern = name)
            bpy.context.scene.objects.active = bpy.data.objects[name]
            bpy.ops.uv.lightmap_pack("EXEC_SCREEN")
            print("Baking " + name)
            bpy.ops.object.bake("INVOKE_DEFAULT") # or EXEC_DEFAULT
        return {'FINISHED'}

I've seen posts about using macros to order sequences of operators, but it doesn't seem possible to configure specific settings (in this case, which object to bake). This is my first foray into Blender scripting, so I'm surely missing something.

How would I achieve this, and are there any best practices I should be be aware of?

UPDATE

After a bit of playing around, I've solved this particular case. The solution is as follows:

class BakeryOperation(bpy.types.Operator):
    bl_idname = "bakery.bake"
    bl_label = "Bake Textures"

    def invoke(self, context, event):
        scn = context.scene
        materials = set()
        bake_pass = scn.bake_passes[scn.bake_passes_index]
        scn.cycles.samples = bake_pass.samples
        for o in scn.bake_objects:
            materials = materials.union(set(map(lambda x: (o.name, x.name), bpy.data.objects[o.name].data.materials)))

        bpy.ops.object.select_all("EXEC_SCREEN", action="DESELECT")
        for (name, material) in materials:
            bpy.data.materials[material].use_nodes = True
            node_tree = bpy.data.materials[material].node_tree
            found = False

            img_name = name+"_bake"
            for n in [n for n in node_tree.nodes if n.type == 'TEX_IMAGE']:
                found = False

                if n.image != None and n.image.name == img_name:
                    n.select = True
                    node_tree.nodes.active = n
                    found = True
                    break
            if not found:
                node = node_tree.nodes.new("ShaderNodeTexImage")
                node.select = True
                node_tree.nodes.active = node
                if img_name in bpy.data.images:
                    node.image = bpy.data.images[img_name]
                else:
                    node.image = bpy.data.images.new(name + "_bake", 512, 512)

            img = bpy.data.images[img_name]

            bpy.ops.uv.lightmap_pack("EXEC_SCREEN", PREF_CONTEXT="ALL_FACES")
            bpy.ops.object.select_pattern("EXEC_SCREEN", pattern = name)
        bpy.ops.object.bake("INVOKE_SCREEN")
        return {'FINISHED'}

Simply selecting all objects and then invoking the bake operation fixes the problem.

Answer 1

In this case, (doh), simply selecting the objects during the loop and then invoking the bake operation does what I need.