Programming for humans with a well-defined __repr__

# default __repr__
>>> random.choice(Unit.get_all())
<module.Unit object at 0x10cff0550>

#After changing the definition__repr__
>>> random.choice(Unit.get_all())
Dragon Mermaid[ID:2001]

The value of __repr__ is also displayed in the error log, which is convenient for debugging. 'self' <Player: id: 123456 name: [Fishman] Orca Spycy Lv: 99>

Verify implementation of repr

python

# -*- coding: utf-8 -*-
from __future__ import absolute_import, unicode_literals


class BaseRepr(object):
    id = 12345
    name = 'Hinata Crab Zou'


class DefaultRepr(BaseRepr):
    pass


class DefaultReprOverWrite(BaseRepr):
    def __repr__(self):
        return '<{0}.{1} object at {2}>'.format(
            self.__module__, type(self).__name__, hex(id(self)))


class CustomRepr(BaseRepr):
    def __repr__(self):
        return '{}[ID:{}]'.format(self.name, self.id)


print DefaultRepr(), DefaultRepr.__name__
print DefaultReprOverWrite(), DefaultReprOverWrite.__name__
print CustomRepr(),  CustomRepr.__name__

Execution result

>>>python test.py 
<__main__.DefaultRepr object at 0x1086018d0> DefaultRepr
<__main__.DefaultReprOverWrite object at 0x1086018d0> DefaultReprOverWrite
Hinata Crab Zou[ID:12345] CustomRepr

Also verify the behavior of __str__ and __unicode__

python

class CustomRepr(BaseRepr):
    def __repr__(self):
        return '{}[ID:{}]'.format(self.name, self.id)

    def __str__(self):
        return '__str__'

    def __unicode__(self):
        return '__unicode__'

print 'str:', str(CustomRepr())
print 'unicode:', unicode(CustomRepr())

Execution result

>>>python test.py 
str: __str__
unicode: __unicode__

If you do not define __str__ and __unicode__

python

class CustomRepr(BaseRepr):
    def __repr__(self):
        return '{}[ID:{}]'.format(self.name, self.id)

print 'str:', str(CustomRepr())
print 'unicode:', unicode(CustomRepr())

Execution result

>>>python test.py 
str:Hinata Crab Zou[ID:12345]
unicode:Hinata Crab Zou[ID:12345]

reference

Python Reference Manual Python str versus unicode Difference between str and repr in Python Hyuga Crab Zou