what's the use of __repr__?when shall I use it?

[could ildg]

What's the difference between __repr__ and __str__?
When will __repr__ be useful?

[Vikram]

__repr__ should return something that when eval'ed yields an identical
object (if possible). essentially it should represent the programmer/debug
view of the object.

__str__ should mostly return a highly user-friendly string (note: str(obj)
will use __repr__ if __str__ doesn't exist)

you might also be interested in this thread covering the same topic:
http://groups-beta.google.com/group/...8f62f478057abd

thanks,
Vikram

[Greg Ewing]

Vikram wrote:

__repr__ should return something that when eval'ed yields an identical
object (if possible).

That's strictly possible in so few cases that it's not
really a very helpful guideline, in my opinion.

I find the following view more helpful:

* str() is for producing the normal output of a program,
to be seen by the user.

* repr() is for debugging output, and should indicate
reasonably unambiguously the *type* of the object.
When debugging, it's often at least as important to
know what type of object you have as what value it
has.

--
Greg Ewing, Computer Science Dept,
University of Canterbury,
Christchurch, New Zealand
http://www.cosc.canterbury.ac.nz/~greg