Weird list in Python

Question

I was trying to fetch a member of my discord server using discord.py. Using the guild.members I was iterating over it, and it returned me the names of the members, but then I printed it directly and I got something like this:

[<Member id=102833403109497170 name='Xiaoling' discriminator='147' bot=False nick=None guild=<Guild id=102393565654216714 name='DarkFuture' chunked=True member_count=22>>, <Member id=94117068084664839 name='Rishit' discriminator='0184' bot=False nick=None guild=<Guild id=1023935685654216714 name='DarkFuture' chunked=True member_count=22>>, <Member id=9417194317169792 name='麦わら帽子・Zoro' discriminator='905' bot=False nick=None guild=<Guild id=102393565654216714 name='DarkFuture' chunked=True member_count=22>>]

Is this a List? I checked its type, and it said list, but it didn’t look like a list to me. If I paste it directly in the code editor, there’s an error highlighting, and if I run it, it gives me a syntax error. What is this? How is Python iterating over it?

I just found a weird list in Python which I don’t know what is and I needed the information.

Asked By: Rishit Chaudhary

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Source

Answer 1

Take a look at the class Member

class Member:
    def __init__(self,id,name,somethingElse=True):
        self.id = id
        self.name = name
        self.somethingElse = somethingElse

    def addExtraValue(self,extra):
        self.extra = extra
    
    def __repr__(self):
        return "<id = {}, name = '{}'>".format(self.id, self.name)

Here,
the Member class has its own attributes like id, name, etc.

Let’s create a list of this class

m1 = Member(1,'name 1')
m1.addExtraValue(15)
m2 = Member(2,'name 2', False)

members = [m1,m2]

When we print members at this point. It will show output like,

[<id = 1, name = 'name 1'>, <id = 2, name = 'name 2'>]

instead of

[<__main__.Member object at 0x7fb9c093e4c0>, <__main__.Member object at 0x7fb9c07e8130>]

It is due to the def __repr__(self) function in class, which is used to create custom output.

I hope this will clear the confusion regarding the print of < mark in the output.

Then, Class attributes are not iterable, hence we can not directly iterate over it or can not access the attributes as a list (i.e. member[key] is not supported).

To solve this issue you can use the eval method as shown below.

possibleKeys = ['id','name','somethingElse','extra']
for member in members:
    for key in possibleKeys:
        try:
            value = eval('member.{}'.format(key))
        except:
            value = 'Not Available'
        print("{} => {}".format(key,value))
    print()

The eval is wrapped in try and catch because the extra attribute is not necessary to be available in all class objects.

I hope this will clear the way to iterate over class objects to get other attributes.

Answered By: Aditya Dhembre

Weird list in Python

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