PCPP1 – Certified Professional Python Programmer Level 1 Free Sample Questions

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.