PCAP Closures and Decorators 3

Question 1

What does `@property` allow you to do in a Python class?

Accepted Answer

Define a method that is accessed like an attribute, triggering computation on read

Answer

Make a class attribute permanently read-only at the metaclass level

Answer

Define compile-time constants that cannot be overridden in subclasses

Answer

Create name-mangled private attributes automatically

Question 2

Which built-in decorator marks a method that receives the class object (not an instance) as its first implicit argument?

Accepted Answer

@classmethod

Answer

@staticmethod

Answer

@property

Answer

@abstractmethod

Question 3

What makes a `@staticmethod` different from a regular instance method?

Accepted Answer

It receives neither self nor cls and is essentially a plain function namespaced inside the class

Answer

It cannot be overridden in subclasses and is resolved at compile time

Answer

It is called automatically when the class is instantiated

Answer

It can only be called once per program execution

Question 4

What is memoization as used in closure-based and decorator-based Python patterns?

Accepted Answer

Caching a function's return values keyed by its arguments so repeated calls skip recomputation

Answer

Storing a function's source code in memory to speed up parsing

Answer

Converting a synchronous function into a coroutine automatically

Answer

Logging every function call to an in-memory buffer for later inspection

Question 5

What does `@functools.lru_cache(maxsize=128)` do to the decorated function?

Accepted Answer

Automatically memoizes return values using a Least-Recently-Used cache limited to 128 entries

Answer

Restricts the function to at most 128 calls per second

Answer

Compresses return values to fit within 128 bytes of memory

Answer

Creates 128 pre-warmed copies of the function for parallel execution

Question 6

What will the following code print?

def decorator(func):
    calls = []
    def wrapper(*args, **kwargs):
        calls.append(args)
        return func(*args, **kwargs)
    wrapper.call_log = calls
    return wrapper

@decorator
def add(a, b): return a + b

add(1, 2)
add(3, 4)
print(len(add.call_log))

Accepted Answer

2

Answer

0

Answer

1

Answer

AttributeError: 'function' object has no attribute 'call_log'

Question 7

A property setter is defined by applying which decorator to a second method with the same name as the getter?

Accepted Answer

@<property_name>.setter

Answer

@property.setter

Answer

@setter(<property_name>)

Answer

@set_property