Free PCPP-32-101 sample questions

Correct answer: Composition and Polymorphism

The `Portfolio` class holding a collection of `Asset` objects is a classic example of Composition (a 'has-a' relationship). Since the collection can contain objects of subclasses like `Stock` and `Bond`, and the `Portfolio` can operate on them through the common `Asset` interface, this demonstrates Polymorphism. Inheritance is shown by `Stock` and `Bond` extending `Asset`, but the question specifically asks about the `Portfolio`'s relationship.

Correct answer: Three nested functions: the outer for the decorator's arguments, the middle to accept the function to be decorated, and the inner to serve as the wrapper.

To create a decorator that accepts arguments, you need a factory pattern. This is typically implemented with three levels of nested functions. The outermost function accepts the decorator's arguments (e.g., `attempts=3`) and returns the actual decorator. The middle function is the decorator itself, which accepts the function to be decorated. The innermost function is the wrapper that contains the new logic and calls the original function.

Correct answer: To create an explicitly chained exception, where the original exception `exc` is preserved in the `__cause__` attribute and included in the traceback.

The `raise NewException from OriginalException` syntax is used for explicit exception chaining. It sets the `__cause__` attribute on the new exception to the original one. This indicates that the new exception was raised in direct response to the original one, and both tracebacks are displayed to aid in debugging.

Correct answer: `requests.get('https://api.example.com/users/123', headers={'X-API-Key': 'secret'})`

The `requests` library uses the `headers` parameter to pass a dictionary of custom HTTP headers. The `data` parameter is used for the request body (typically in POST or PUT), `params` is for URL query parameters, and `auth` is for specific authentication schemes like Basic or Digest auth.

Correct answer: `if not my_list:`

PEP 8 recommends using the fact that empty sequences are 'falsy' in a boolean context. Therefore, `if not my_list:` is the preferred, more Pythonic way to check for an empty list, dictionary, or other collection. While `len(my_list) == 0` works, it is considered less idiomatic.

Correct answer: Open the file with `w` mode and `newline='`', use `csv.DictWriter` and its `writerow` method.

The `csv.DictWriter` class is specifically designed to write rows from dictionaries. It requires a `fieldnames` argument during instantiation to define the header. Its `writerow` method then takes a dictionary and writes the values corresponding to the fieldnames. It's crucial to open the file with `newline=''` to prevent extra blank rows from being written on some platforms.

Correct answer: `grid` arranges widgets relative to each other in a grid, making it good for responsive layouts, while `place` uses absolute or relative coordinates, making it rigid.

The `grid` manager organizes widgets in a table-like structure of rows and columns. This allows the layout to adapt as the window is resized. In contrast, the `place` manager positions widgets at specific x/y coordinates (either absolute pixels or relative to the container size), which does not automatically adjust well to window resizing, making it less suitable for most applications.

Correct answer: `__getitem__(self, key)`

The `__getitem__` method is used to implement evaluation of `self[key]`, which is how dictionary values are accessed. By implementing this method, the developer can add custom logic (like logging) before retrieving and returning the value. `__getattr__` is for attribute access (e.g., `self.key`), and `__get__` is part of the descriptor protocol.

Correct answer: `shelve` allows for random access to stored objects via keys, similar to a dictionary, while `pickle` requires sequential reading of the entire file.

The main advantage of `shelve` is its dictionary-like interface. It stores pickled objects in a database file, allowing you to access, add, or modify individual objects by their string key without having to load and rewrite the entire data structure. In contrast, `pickle` typically serializes an entire object graph to a stream, which must be read sequentially.

Correct answer: False

The statement is false. It has the constants reversed. `socket.SOCK_STREAM` is used for connection-oriented TCP sockets, while `socket.SOCK_DGRAM` is used for connectionless UDP sockets.