Final Exam Review: Exceptions and Generators

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Questions and Answers

What is the purpose of an accumulator in a for-loop?

An accumulator stores information computed in the for-loop and retains it after the loop completes.

How does an assert statement function in Python?

An assert statement checks if a boolean expression is true; if false, it raises an error and can include an error message.

Differentiate between instance attributes and class attributes.

Instance attributes belong to individual objects, while class attributes are shared across all instances of the class.

What is meant by attribute invariants?

Attribute invariants are conditions that maintain certain constraints on attributes to ensure they meet specific requirements. Signup and view all the answers

Describe the Bottom-Up Rule in Python.

The Bottom-Up Rule determines the method or attribute to use in an expression based on the object's class hierarchy, starting from the object's class to the parent classes. Signup and view all the answers

In what way can hiding attributes improve class design?

Hiding attributes (using underscores) promotes encapsulation and prevents direct modification, allowing the use of getter and setter methods. Signup and view all the answers

What role do attributes play within an object in Python?

Attributes store data or state specific to an object, providing a structure for characteristics and behaviors. Signup and view all the answers

Explain how an accumulator is typically implemented in a for-loop with an example.

An accumulator is initialized before the loop, and within the loop, it aggregates values, such as: <code>total = 0; for x in range(5): total += x</code>. Signup and view all the answers

What is a call frame in Python and what information does it contain?

A call frame is a formal representation used during a function call, containing the function's name, parameters, local variables, and an instruction counter to track the next line to execute. Signup and view all the answers

Describe the call stack and its structure during function execution.

The call stack is a collection of all the call frames of currently executing function calls, arranged such that the original function is at the top and the most recent call is at the bottom. Signup and view all the answers

What happens to a call frame once a function call is completed in Python?

Once a function call is completed, the call frame is deleted or erased from the memory. Signup and view all the answers

How is a new call frame added to the call stack when a function calls another function?

When a function calls a helper function, a new call frame is added to the bottom of the call stack. Signup and view all the answers

What is the role of the instruction counter in a call frame?

The instruction counter in a call frame tracks the next line of code to be executed in the function. Signup and view all the answers

Explain what occurs if an attribute or method is found in multiple locations in Python's class hierarchy.

If an attribute or method is found in multiple locations, Python uses the first one it encounters in the search order. Signup and view all the answers

Can you define what a constructor is in the context of class creation in Python?

A constructor is a special function that creates an object for a class, initializes it in heap space, and returns the object's name. Signup and view all the answers

What is the significance of the init method in Python classes?

The init method is an initializer that executes automatically when a new object is created, setting the initial values of the object's attributes. Signup and view all the answers

What is the purpose of a call frame in the context of function execution?

A call frame stores information about a function call, including local variables, parameters, and the return address. Signup and view all the answers

How does a call stack evolve during recursive function calls?

The call stack grows with each recursive call by adding new call frames, and shrinks when functions return. Signup and view all the answers

What is the significance of the return address stored in a call frame?

The return address indicates where the program should continue execution after the function call returns. Signup and view all the answers

What happens to the local variables when a function exits and its call frame is removed?

Local variables are deallocated and cannot be accessed once the call frame is removed. Signup and view all the answers

What is the structure of a call stack when multiple functions are called sequentially?

The call stack contains call frames for each called function, with the most recent call on top. Signup and view all the answers

How can visualization of a call frame help in debugging recursive functions?

Visualization helps track the values of parameters and local variables at each level of recursion, making it easier to identify errors. Signup and view all the answers

Explain the relationship between call frames and memory representation in programming.

Call frames reside in the stack segment of memory, while global variables are stored in the global space. Signup and view all the answers

In what scenario would a call frame remain for an extended period of time during function execution?

A call frame remains extended during a long-running recursive call that hasn't reached a base case. Signup and view all the answers

Flashcards

Accumulator

A variable inside a loop that stores information computed during the loop. It retains its value even after the loop ends.

Assert Statement

A statement that checks a boolean expression. If it's false, it causes an error and stops the program.

Attribute

A variable associated with an object, holding data about the object's state.

Instance Attribute

An attribute specific to an individual instance of a class, accessible only for that instance object.