Immutable and equality

Questions 1 to 5 of 8

1. 1. What does this program print? ``python from dataclasses import dataclass, replace @dataclass(frozen=True) class Point: x: int y: int p = Point(3, 4) moved = replace(p, x=p.x + 10) print(p, moved) ``

   Point(x=3, y=4) Point(x=13, y=4)Point(x=13, y=4) Point(x=13, y=4)Point(x=3, y=4) Point(x=3, y=14)Point(x=13, y=4) Point(x=3, y=4)
2. 2. A dataclass Range checks in __post_init__ that low is not above high. What does Range(9, 2) do? ``python @dataclass(frozen=True) class Range: low: int high: int def __post_init__(self): if self.low > self.high: raise ValueError(f"low {self.low} is above high {self.high}") ``

   It creates a Range with a length of -7It returns None, and the program keeps runningIt swaps low and high, so the result is a Range from 2 to 9It raises ValueError, and the caller gets no Range object
3. 3. The output shows a change to an object that was meant to be fixed. What is the bug? ``python from dataclasses import dataclass @dataclass(frozen=True) class Team: name: str members: list names = ["Asha"] team = Team("Blue", names) names.append("Ravi") print(team) ` Output: Team(name='Blue', members=['Asha', 'Ravi'])`

   Dataclasses cannot hold a list, so members should be declared with field(default_factory=list)The frozen flag copies each argument when the object is built, so names.append should never reach the teamThe frozen flag stops team.members from being reassigned, but the list it points to is shared with the caller, so names.append changes the teamThe team needs a set_members method before names.append can change it
4. 4. True or false: for @dataclass class Point: x: int, the way to read the value is p.get_x(), because dataclasses write a getter for every field.

   False, because a dataclass field is read directly as p.x, with no getter methodTrue, because dataclasses write get_ methods for every field
5. 5. What does this program print? ``python class Money: def __init__(self, cents): self._cents = cents def __eq__(self, other): if not isinstance(other, Money): return NotImplemented return self._cents == other._cents def __hash__(self): return hash(self._cents) a = Money(1050) b = Money(1050) print(a == b, a is b, a == "$10.50") ``

   True True FalseTrue False FalseFalse False FalseTrue False True