PCPP2 Practice Questions 1 — 50 Questions

Question 1

Which keyword is used to raise an exception in Python?

Accepted Answer

raise. The raise keyword is used to trigger an exception.

Answer

trigger

Answer

throw

Answer

catch

Question 2

When using SQLAlchemy Declarative Base, how do you define a table name that differs from the class name?

Accepted Answer

Set __tablename__ = 'name'. The __tablename__ attribute is used to explicitly map a class to a specific table name.

Answer

Set __table_name__ = 'name'

Answer

Map it in the metadata object.

Answer

Use the 'table' argument in the class definition.

Question 3

You need to ensure that a class can only be instantiated once throughout the application lifecycle. Which design pattern is most appropriate?

Accepted Answer

Singleton Pattern. The Singleton pattern ensures that a class has only one instance and provides a global point of access to it.

Answer

Factory Pattern

Answer

Adapter Pattern

Answer

Proxy Pattern

Question 4

When using inheritance, how can you explicitly call a method from a specific parent class that is not the immediate superclass?

Accepted Answer

BaseClass.method(self). Calling the method directly on the class object (e.g., Parent.method(self)) bypasses the MRO.

Answer

self.method()

Answer

Using the __parent__ attribute

Answer

super().method()

Question 5

When writing a context manager using the @contextlib.contextmanager decorator, what should the function do to pass a value to the 'as' clause?

Accepted Answer

Yield the value. The yield statement in a decorated generator function passes the value to the with statement's as target.

Answer

Assign to a global variable

Answer

Use the return statement

Answer

Raise an exception

Question 6

You need to ensure that a method can be called on the class directly, without requiring an instance. Which decorator should be used?

Accepted Answer

@classmethod. The @classmethod decorator receives the class as the first argument, allowing factory-style methods.

Answer

@property

Answer

@abstractmethod

Answer

@staticmethod

Question 7

Which THREE of the following features are common to both the threading and multiprocessing modules?

Accepted Answer

The start() method to begin execution.. Both modules provide mechanisms for joining, starting, and using locks for synchronization.

Answer

Direct access to the GIL.

Answer

Automatic shared memory.

Question 8

Which THREE of the following are benefits of using __slots__?

Accepted Answer

Faster attribute access. __slots__ reduces memory usage, prevents the creation of __dict__, and can potentially speed up attribute access.

Answer

Automatic support for multiple inheritance

Answer

Automatic serialization

Question 9

Which TWO of the following are potential issues when using the 'fork' start method in multiprocessing?

Accepted Answer

Threads present in the parent may not be safe in the child.. Forking a process inherits the parent's memory, which can lead to issues with locks and threads.

Answer

It cannot share data at all.

Answer

It crashes on all Unix systems.

Answer

It is always slower than spawn.

Question 10

Which command-line argument shows the values of local variables in the event of a test failure?

Accepted Answer

--showlocals. The --showlocals flag instructs pytest to display local variables in the traceback output upon failure.

Answer

--debug

Answer

--traceback

Answer

--locals

Question 11

Which THREE of the following are valid address families or socket types used with the Python socket module?

Accepted Answer

socket.AF_INET. AF_INET and AF_INET6 are common address families, while SOCK_STREAM and SOCK_DGRAM are standard socket types.

Answer

socket.AF_TCP

Answer

socket.SOCK_LOCAL

Question 12

You are designing a class hierarchy where a subclass needs to ensure it calls the constructor of its parent in a multiple inheritance scenario. Which mechanism is the standard Pythonic approach to handle this dynamically?

Accepted Answer

Using super().__init__(). super() is the standard way to delegate to the next class in the Method Resolution Order (MRO).

Answer

Explicitly calling ParentClass.__init__(self)

Answer

Manually tracking parent states in a registry

Answer

Using the __init__subclass__ hook

Question 13

You are handling large datasets and want to improve memory efficiency. Which Python feature allows you to iterate over a large sequence without loading it entirely into memory?

Accepted Answer

Generators. Generators provide a lazy evaluation mechanism to yield items one at a time.

Answer

Deepcopy

Answer

Set literals

Answer

List comprehensions

Question 14

When using a multiprocessing.Queue to share data between processes, what happens if the queue is full and you use the put() method without a timeout?

Accepted Answer

It blocks indefinitely until a slot becomes available.. By default, put() is a blocking operation that will wait until a slot is available if the queue is full.

Answer

It restarts the child process.

Answer

It raises a Full exception immediately.

Answer

It silently drops the data.

Answer

It overwrites the oldest item in the queue.

Question 15

Which TWO of the following are valid ways to execute a raw SQL query in SQLAlchemy?

Accepted Answer

Using engine.execute('SELECT * FROM table'). SQLAlchemy allows executing raw SQL via text() with engine.execute() or session.execute().

Answer

Using session.query(RawSQL('SELECT * FROM table'))

Answer

Using session.commit('SELECT * FROM table')

Answer

Using table.run('SELECT * FROM table')

Question 16

You are utilizing abstract base classes (ABCs). How do you enforce that a subclass implements a specific method?

Accepted Answer

Use the @abstractmethod decorator. The @abstractmethod decorator marks a method as requiring implementation in concrete subclasses.

Answer

Use a metaclass check

Answer

Raise NotImplementedError in the base class

Answer

Pass the method name to __init__

Question 17

Which command-line tool is typically used to inspect the contents of a SQLite database file?

Accepted Answer

sqlite3. The 'sqlite3' command-line interface is the standard tool to interact with .db files.

Answer

mysql

Answer

mongo

Answer

psql

Question 18

Which built-in function allows you to retrieve an attribute from an object by its string name?

Accepted Answer

getattr(). getattr() is the built-in function to access object attributes dynamically.

Answer

fetch()

Answer

getattribute()

Answer

access()

Question 19

You are using the multiprocessing.Process class and notice that child processes are not terminating cleanly. Which method should you call to ensure the main process waits for the child process to complete?

Accepted Answer

process.join(). The join() method blocks the calling thread until the process whose join() method is called terminates.

Answer

process.wait()

Answer

process.terminate()

Answer

process.close()

Answer

process.is_alive()

Question 20

Two threads are modifying a shared global integer. You want to ensure that only one thread modifies the integer at a time. Which synchronization primitive is most appropriate?

Accepted Answer

threading.Lock. A Lock (or Mutex) is the standard tool to ensure mutually exclusive access to a shared resource.

Answer

threading.Event

Answer

multiprocessing.Semaphore

Answer

multiprocessing.Queue

Answer

threading.Condition