title: Casting to Int and Float
tags: python

Three relatively unknown `__dunder__` methods, `__int__` and `__float__`, and `__bool__`
define the result of casting to `int`, `float`, and `bool` respectively
```py
class A:
  def __int__(self):
    return 42
  def __float__(self):
    return 3.14159
  def __bool__(self):
    return True

a = A()
print(int(a))
# 42
print(float(a))
# 3.14159
print(bool(a))
# True
```

# Dict and List
As for `dict` and `list`, these rely in using an iterator obtained via the `__iter__` method:
```py
class A:
  def __iter__(self):
    return iter([("pi",3.14159),("answer",42)])

a = A()
print(dict(a))
# {'pi': 3.14159, 'answer': 42}
print(list(a))
# [('pi', 3.14159), ('answer', 42)]
```