FAQ: __str__ vs __repr__

[Peter Hansen]

Jan Danielsson wrote:
>   Sorry, but I Just Don't Get It. I did search the 'net, I did read the
> FAQ, but I'm too dumb to understand.
> 
> As far as I can gather, __str__ is just a representation of the
> object. [snip]

> However, I don't understand what __repr__ should be. 

__repr__ shouldn't be anything, if you don't have an actual need for it. 
  Neither should __str__.

But if you have a need for something, and you're not sure which to use, 
think of it this way.  If you are trying to output a representation of 
the object for use in debugging, such as in a debug log file, then use 
__repr__ and make it look like whatever you want, but preferably 
following the <Angle brackets convention> like all the builtin stuff.

If you have a need for some representation of the data to use in your 
application for non-debugging purposes, such as perhaps to display data 
to a user, or to write data to an output file, then __str__ is a good 
candidate, and you can make it look like whatever you need.

Just don't waste your time defining either a __repr__ or a __str__ just 
because those methods exist.  That won't do anyone any good.

-Peter