Python如何通过其属性查找对象？

Question

Is there a way to get an object by matching it up with its attributes? For example:

class band:
    def __init__(self, name, number):
    self.name = name
    self.number = number


rivers = band("rivers", 1)
patrick = band("pat" , 2)
brian = band("brian" , 3)
scott = band("scott", 4)

In this code, is there a way for me to use a number(lets say 1), to find the object rivers within the band class and get its name attribute?

Thank you for taking your time to read this and have a nice day.

Answer 1

In this code, is there a way for me to use a number(lets say 1), to find the object rivers within the band class and get its name attribute?

In this code, NO. Because you do not save the value of name to the class property.

However, if your class structure was like:

class band:
    def __init__(self, name, number):
        self.number = number
        self.name = name   # <--- Here is the difference

you could have done it. Let say rivers , patrick , brian and scott are part of the list as:

my_list = [rivers, patrick, brian, scott]

Iterate over the list and print the name of class for which value of number is 1 as:

for item in my_list:
    if item.number == 1:
        print item.name 

Answer 2

You may store a dictionary mapping number to band in order to achieve that.

For example

bands = {}

class band:
   def __init__(self, name, number):
      self.number = number
      self.name = name
      bands[number] = self

def getBandFromNumber(number):
   return bands[number]