PCPP1 Practice Test 4 — 25 Questions

Question 1

You want to bind a function 'on_click' to a left mouse button click on a Button widget. Which event sequence string is correct?

Accepted Answer

. The event sequence '' corresponds to the primary (left) mouse button.

Answer

<Mouse-1>

Answer

<Left-Click>

Answer

<Click-1>

Question 2

How do you implement the 'Strategy' pattern in Python?

Accepted Answer

By passing strategy instances into the context constructor.. By injecting different strategy objects into a context class, which then delegates operations to the injected object.

Answer

By using a large switch-case statement.

Answer

By creating a metaclass for all strategies.

Answer

By using inheritance for every strategy.

Question 3

According to PEP 257, what is the standard format for a single-line docstring?

Accepted Answer

Use triple quotes and keep the summary on the same line, ending with a period.. A single-line docstring should be on the same line as the opening triple quotes, ending with a period.

Answer

Use a single quote for the entire block.

Answer

The docstring should span three lines including the summary.

Answer

The summary should start on the next line.

Question 4

You have a Checkbutton and you need to track its state. What is the recommended way to associate a variable with the Checkbutton?

Accepted Answer

Pass a BooleanVar object to the 'variable' parameter.. A BooleanVar or IntVar should be passed to the 'variable' parameter of the Checkbutton.

Answer

Use the 'onvalue' parameter.

Answer

Use the state attribute directly.

Answer

Use the 'command' parameter to set a global flag.

Question 5

Which method on a widget instance causes it to be removed from the display, but not destroyed?

Accepted Answer

widget.pack_forget(). The pack_forget() (or grid_forget()) method hides a widget from the layout manager.

Answer

widget.hide()

Answer

widget.remove()

Answer

widget.delete()

Question 6

Which THREE of the following widgets are part of the 'ttk' (Themed Tkinter) module?

Accepted Answer

ttk.Entry. ttk.Button, ttk.Label, and ttk.Entry are part of the themed widget set, whereas standard tkinter widgets are in the top-level tkinter module.

Answer

ttk.Window

Answer

ttk.Canvas

Question 7

You want to create a Menu that contains sub-menus. Which class or method is used to add a sub-menu to an existing menu?

Accepted Answer

menu.add_cascade(). The add_cascade method is used to create a menu item that opens a sub-menu.

Answer

difficulty

Answer

menu.add_menu()

Answer

menu.add_command()

Answer

menu.add_submenu()

Question 8

In the context of the Descriptor Protocol, what is the primary difference between a data descriptor and a non-data descriptor?

Accepted Answer

Data descriptors define __set__ or __delete__, whereas non-data descriptors do not.. A data descriptor defines both __get__ and __set__ (or __delete__), while a non-data descriptor only defines __get__.

Answer

Non-data descriptors can override instance dictionary lookup.

Answer

Data descriptors only function with class attributes.

Answer

Non-data descriptors are always read-only.

Question 9

Which magic method should you implement to make your objects support the 'with' statement context manager?

Accepted Answer

__enter__ and __exit__. The __enter__ and __exit__ methods are required to implement the context manager protocol.

Answer

__context__

Answer

__open__ and __close__

Answer

__init__ and __del__

Question 10

In the context of the Observer pattern, what is the benefit of an event-driven system over a direct-method-call approach?

Accepted Answer

Decoupling between the subject and observers.. Decoupling is the primary benefit; the subject does not need to know the implementation details of the observers.

Answer

Reduced memory usage.

Answer

Increased performance.

Answer

Automatic thread synchronization.

Question 11

Which THREE of the following are true about the Python descriptor protocol?

Accepted Answer

They must be defined in the class body.. Descriptors allow you to manage attribute access, they have specific lookup order, and they are used by property/classmethod internally.

Answer

Non-data descriptors can define __set__.

Answer

They only work for instance attributes.

Question 12

You are configuring logging using a dictConfig. You want to send logs to a RotatingFileHandler. Which key must you define in the 'handlers' section?

Accepted Answer

class. The 'class' key is required to specify the handler type, e.g., 'logging.handlers.RotatingFileHandler'.

Answer

destination

Answer

type

Answer

handler_type

Question 13

When designing a public API, how should you signal that a method is for internal use only?

Accepted Answer

By prepending a single underscore.. Prefixing a name with a single underscore is the conventional way to indicate internal use.

Answer

By raising a warning if called externally.

Answer

By adding a comment like '# INTERNAL'.

Answer

By using all caps.

Answer

By suffixing with an underscore.

Question 14

Which comment style is preferred for block comments in Python?

Accepted Answer

Each line starting with a single '#' and a space.. Block comments should consist of paragraphs of text, each starting with a # and a single space.

Answer

Using a string literal (triple quotes) at the top level.

Answer

Using block comments inside a single line.

Answer

Using a single '#' at the end of every line.

Question 15

Which TWO practices help maintain clean code when using Python's 'try-except' blocks?

Accepted Answer

Keep the 'try' block as small as possible.. Keep the try block small and catch specific exceptions.

Answer

Use a single 'except:' clause for the whole project.

Answer

Always ignore errors in the 'except' block.

Answer

Put as much code as possible in the 'try' block.

Question 16

To prevent a user from editing text in a widget, which configuration option should you set?

Accepted Answer

state=tk.DISABLED. Setting 'state' to 'disabled' prevents user interaction with the widget.

Answer

editable=False

Answer

enabled=False

Answer

readonly=True

Question 17

When binding an event to a widget using 'widget.bind('<Key>', handler)', the handler function receives an event object. How do you access the specific character pressed?

Accepted Answer

handler(event.char). The event object passed to the handler contains the 'char' attribute which holds the character pressed.

Answer

handler(event.keysym)

Answer

handler(event.get_char())

Answer

handler(event.key)

Answer

difficulty

Question 18

Which THREE of the following represent common issues when using __slots__?

Accepted Answer

Subclasses must define their own __slots__ to avoid creating a __dict__.. Slots can break pickling in some cases, make multiple inheritance tricky, and prevent adding attributes dynamically.

Answer

They are incompatible with all decorators.

Answer

They prevent the use of multiple inheritance.

Question 19

Which TWO of the following are secure coding practices in Python?

Accepted Answer

Avoid using 'pickle' for untrusted data.. Avoiding dangerous functions and validating all inputs are key security practices.

Answer

Use 'subprocess' with 'shell=True'.

Answer

Always use 'eval()' for dynamic execution.

Answer

Use hardcoded credentials for database connections.

Question 20

You want to trigger a function when a user releases a key. Which event string should you use with bind()?

Accepted Answer

. The '' event is used to detect when a key is released.

Answer

<Key-Up>

Answer

Answer

<KeyUp>