Quick Modifiers Modal

operator_modal.py

import bpy
from bpy.props import IntProperty, FloatProperty


class ModalOperator(bpy.types.Operator):
    """Move an object with the mouse, example"""
    bl_idname = "object.modal_operator"
    bl_label = "Simple Mirror"

    first_mouse_x = IntProperty()
    first_value = FloatProperty()

    mesh = bpy.context.active_object
    
    def modal(self, context, event):
        
        if event.type == 'LEFTMOUSE' and event.value == 'PRESS':
            obj = bpy.context.active_object
            print(obj)
            return {'PASS_THROUGH'}
        
        elif event.type == 'SPACE':
            
            bpy.context.scene.objects.active = self.mesh
            bpy.ops.object.modifier_add(type='MIRROR')
            
            self.mesh.select = True
            return {'FINISHED'}

        elif event.type in {'RIGHTMOUSE', 'ESC'}:
            return {'CANCELLED'}

        return {'RUNNING_MODAL'}

    def invoke(self, context, event):
        
        if context.object:
            context.window_manager.modal_handler_add(self)
            self.header_message = "Select an object"
            return {'RUNNING_MODAL'}
        else:
            self.report({'WARNING'}, "No active object, could not finish")
            return {'CANCELLED'}


def register():
    bpy.utils.register_class(ModalOperator)


def unregister():
    bpy.utils.unregister_class(ModalOperator)


if __name__ == "__main__":
    register()