PCPP-32-101 Sample Questions Answers

A. The sqlite3 module in python provides an interface compliant to the DB-API 2.0. Thus, it follows a standard performance metric that allows for consistency in database programming with python.

B. The special name 'memory' is used to create a database in RAM using the sqlite3 module. Thus, when you use it as the name of the database file while opening a connection, it creates a temporary database that exists only in memory.

ElementTree is a Python built-in module that provides a simple and efficient API for parsing and creating XML data. It allows you to access and manipulate XML data in a very straightforward way, making it easy to write XML processing applications.

Composition is an object-oriented design concept that models a has-a relationship. In composition, a class known as composite contains an object of another class known as component. In other words, a composite class has a component of another class1.

B. Composition allows a class to be projected as a container of different classes.

Composition is a concept in Python that allows for building complex objects out of simpler objects, by aggregating one or more objects of another class as attributes. The objects that are aggregated are generally considered to be parts of the whole object, and the containing object is often viewed as a container for the smaller objects.

In composition, objects are combined in a way that allows for greater flexibility and modifiability than what inheritance can offer. With composition, it is possible to create new objects by combining existing objects, by using a container object to host other objects. By contrast, with inheritance, new objects extend the behavior of their parent classes, and are limited by that inheritance hierarchy.

References:

• Official Python documentation on Composition: https://docs.python.org/3/tutorial/classes.html#composition
• GeeksforGeeks article on Composition vs Inheritance: https://www.geeksforgeeks.org/composition-vs-inheritance-python/
• Real Python article on Composition and Inheritance: https://realpython.com/inheritance-composition-python/

The correct answer is D. The code is responsible for the support of the inequality operator i.e. i != j. In the given code snippet, the __ne__ method is a special method that overrides the behavior of the inequality operator != for instances of the MyClass class. When the inequality operator is used to compare two instances of MyClass, the __ne__ method is called to determine whether the two instances are unequal.

In Python, type is the built-in metaclass that serves as the base class for all new-style classes. All new-style classes in Python, including built-in types like int and str, are instances of the type metaclass and inherit from it.

The json.dumps() function is used to convert a Python object into a JSON string 1. It takes Python data as its argument, such as a dictionary or a list, and returns a JSON string.

In the JSON processing context, the term serialization: A. names a process in which Python data is turned into a JSON string.

Serialization refers to the process of converting a data object, such as a Python object, into a format that can be easily transferred over a network or stored in a file. In the case of JSON, serialization refers to converting Python data into a string representation using the JSON format. This string can be sent over a network or stored as a file, and later deserialized back into the original Python data object.

The true statement related to PEP 257 is Option B. According to PEP 257, string literals occurring elsewhere in Python code may also act as documentation. They are not recognized by the Python bytecode compiler and are not accessible as runtime object attributes (i.e. not assigned to doc), but two types of extra docstrings may be extracted by software tools: String literals occurring immediately after a simple assignment at the top level of a module, class, or init method are called “attribute docstrings”. String literals occurring immediately after another docstring are called “additional docstrings”1.

Option B is true because the unbind() method is invoked from within a widget’s object 1.

Option D is true because the unbind() method needs the event name as an argument 1.

The unbind() method in Tkinter is used to remove a binding between an event and a function. It can be invoked from within a widget's object when a binding is no longer needed. The method requires the event name as an argument to remove the binding for that specific event. For example:

button = tk.Button(root, text="Click me")

button.bind("", callback_function) # bind left mouse click event to callback_function

button.unbind("") # remove the binding for the left mouse click event

The dump() method in the xml.etree.ElementTree module allows you to output a debug representation of an XML tree to a file or standard output. This method is useful for analyzing the structure of the tree and tracking down errors.