design-patterns/creational/prototype/main.py
Ruidy 7b0e4a5801
Singleton (#6)
* singleton example

* chore: enforce style guidelines
2020-09-14 21:27:39 +02:00

85 lines
2.8 KiB
Python

import copy
from components import SelfReferencingEntity, SomeComponent
list_of_objects = [1, {1, 2, 3}, [1, 2, 3]]
circular_ref = SelfReferencingEntity()
component = SomeComponent(23, list_of_objects, circular_ref)
circular_ref.set_parent(component)
shallow_copied_component = copy.copy(component)
# Let's change the list in shallow_copied_component and see if it changes in
# component.
shallow_copied_component.some_list_of_objects.append("another object")
if component.some_list_of_objects[-1] == "another object":
print(
"""Adding elements to `shallow_copied_component`'s some_list_of_objects
adds it to `component`'s some_list_of_objects."""
)
else:
print(
"""Adding elements to `shallow_copied_component`'s some_list_of_objects
doesn't add it to `component`'s some_list_of_objects."""
)
# Let's change the set in the list of objects.
component.some_list_of_objects[1].add(4)
if 4 in shallow_copied_component.some_list_of_objects[1]:
print(
"Changing objects in the `component`'s some_list_of_objects "
"changes that object in `shallow_copied_component`'s "
"some_list_of_objects."
)
else:
print(
"Changing objects in the `component`'s some_list_of_objects "
"doesn't change that object in `shallow_copied_component`'s "
"some_list_of_objects."
)
deep_copied_component = copy.deepcopy(component)
# Let's change the list in deep_copied_component and see if it changes in
# component.
deep_copied_component.some_list_of_objects.append("one more object")
if component.some_list_of_objects[-1] == "one more object":
print(
"Adding elements to `deep_copied_component`'s "
"some_list_of_objects adds it to `component`'s "
"some_list_of_objects."
)
else:
print(
"Adding elements to `deep_copied_component`'s "
"some_list_of_objects doesn't add it to `component`'s "
"some_list_of_objects."
)
# Let's change the set in the list of objects.
component.some_list_of_objects[1].add(10)
if 10 in deep_copied_component.some_list_of_objects[1]:
print(
"Changing objects in the `component`'s some_list_of_objects "
"changes that object in `deep_copied_component`'s "
"some_list_of_objects."
)
else:
print(
"Changing objects in the `component`'s some_list_of_objects "
"doesn't change that object in `deep_copied_component`'s "
"some_list_of_objects."
)
print(
f"id(deep_copied_component.some_circular_ref.parent): "
f"{id(deep_copied_component.some_circular_ref.parent)}"
)
print(
f"id(deep_copied_component.some_circular_ref.parent.some_circular_ref.parent): "
f"{id(deep_copied_component.some_circular_ref.parent.some_circular_ref.parent)}"
)
print(
"^^ This shows that deepcopied objects contain same reference, they "
"are not cloned repeatedly."
)