当在 Python 中给出类属性之一的值时，如何访问列表中的类对象？

Question

I have a list of class objects and I want to know how can I print a particular class object inside the list given a value for one of its attributes.

Here is my code:

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age

lst = [Person("A",1), Person("B",2), Person("C", 3)]

inputAge = int(input("Age: "))

if inputAge == 2:
  print() #this should print the class object with age 2 from the list 

I don't know what should I put inside the print() code.

Answer 1

This is how you can find the first element of the list having a specific attribute (precondition: all objects of the list have that attribute):

obj = next((x for x in lst if x.age == inputAge), None)

obj is None if such an object can't be found in the list.

Once you found the object, you can do whatever you want with it, including printing ( print(obj) ).

If you want the printing of the object to be meaningful you would have to do something like this:

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age
  def __str__(self):
    return 'name: ' + self.name + ' age: ' + self.age

This is the complete example:

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age
  def __str__(self):
    return 'name: ' + self.name + ' age: ' + self.age

lst = [Person("A",1), Person("B",2), Person("C", 3)]

inputAge = int(input("Age: "))
obj = next((x for x in lst if x.age == inputAge), None)
print(obj) # prints the object with age = inputAge