How do I change the string representation of a Python class

Question

In Java  I can override the toString   method of my class  Then Java s print function prints the string representation of the object defined by its toString    Is there a Python equivalent to Java s toString     For example  I have a PlayCard class  I have an instance c of PlayCard  Now    gt  gt  gt  print c   lt   main   Card object at 0x01FD5D30 gt    But what I want is something like    gt  gt  gt  print c  A    How do I customize the string representation of my class instances   I m using Python 3 x

User · Accepted Answer

The closest equivalent to Java s toString is to implement   str   for your class  Put this in your class definition   def   str   self        return  foo    You may also want to implement   repr   to aid in debugging   See here for more information    Special Method Names - Basic Customization

User · Answer

This is not as easy as it seems  some core library functions don t work when only str is overwritten  checked with Python 2 7   see this thread for examples How to make a class JSON serializable Also  try this  import json  class A unicode       def   str   self           return  a      def   unicode   self           return u a      def   repr   self           return  a   a   A   json dumps a    produces         and not    a     as would be expected   EDIT  answering mchicago s comment   unicode does not have any attributes -- it is an immutable string  the value of which is hidden and not available from high-level Python code  The json module uses re for generating the string representation which seems to have access to this internal attribute  Here s a simple example to justify this   b   A  b   print b  produces   a    while  json dumps   b   b    produces    b    b     so you see that the internal representation is used by some native libraries  probably for performance reasons   See also this for more details  http   www laurentluce com posts python-string-objects-implementation

[python] How do I change the string representation of a Python class?

Examples related to python

Examples related to string

Examples related to python-3.x

Examples related to printing