repr

Lately, I've had lots of trouble with __repr__() , format() , and encodings. Should the output of __repr__() be encoded or be a unicode string? Is there a best encoding for the result of __repr__() in Python? What I want to output does have non-ASCII characters. I use Python 2.x, and want to write code that can easily be adapted to Python 3. The program thus uses # -*- coding: utf-8 -*- from __future__ import unicode_literals, print_function # The 'Hello' literal represents a Unicode object Here are some additional problems that have been bothering me, and I'm looking for a solution that

It was my understanding that python will print the repr of the output, but this is apparently not always the case. For example: In ipython: In [1]: type([]) Out[1]: list In [2]: set([3,1,2]) Out[2]: {1, 2, 3} In python: >>> type([]) <type 'list'> >>> set([3,1,2]) set([1, 2, 3]) What transformation does ipython apply on the output? Instead of repr or standard pprint module IPython uses IPython.lib.pretty.RepresentationPrinter.pretty method to print the output . Module IPython.lib.pretty provides two functions that use RepresentationPrinter.pretty behind the scenes. IPython.lib.pretty.pretty

I've only seen examples for setting the __repr__ method in class definitions. Is it possible to change the __repr__ for functions either in their definitions or after defining them? I've attempted without success... >>> def f(): pass >>> f <function f at 0x1026730c8> >>> f.__repr__ = lambda: '<New repr>' >>> f <function __main__.f> Yes, if you're willing to forgo the function actually being a function. First, define a class for our new type: import functools class reprwrapper(object): def __init__(self, repr, func): self._repr = repr self._func = func functools.update_wrapper(self, func) def _

What does <function at 'somewhere'> mean? Example: >>> def main(): ... pass ... >>> main <function main at 0x7f95cf42f320> And maybe there is a way to somehow access it using 0x7f95cf42f320 ? You are looking at the default representation of a function object. It provides you with a name and a unique id, which in CPython happens to be a memory address. You cannot access it using the address; the memory address is only used to help you distinguish between function objects. In other words, if you have two function objects which were originally named main , you can still see that they are

This question already has an answer here: Difference between __str__ and __repr__? 22 answers what is the difference between str() and repr() functions in python 2.7.5? Explanation on python.org: The str() function is meant to return representations of values which are fairly human-readable , while repr() is meant to generate representations which can be read by the interpreter (or will force a SyntaxError if there is no equivalent syntax) But it wasn't clear for me. some examples: >>> s = 'Hello, world.' >>> str(s) 'Hello, world.' >>> repr(s) "'Hello, world.'" # repr is giving an extra double