newbie: question about "__repr__"

[chenyu]

Hi,
I have read others' code for study, and found one built-in function
"__repr__". Could anyone give me an simple example for explaining
"when and how" to use it.


Thank you for your attention.
kind regards/chenyu

 

[John Roth]

Hi,
I have read others' code for study, and found one built-in function
"__repr__". Could anyone give me an simple example for explaining
"when and how" to use it.

__repr__ is the "magic method" that is used by the repr() built-in
function. It's similar to the str() built-in, but they serve different
purposes. str() is for when you want a human-readable representation,
repr() is for when you want more detail; most objects try to make whatever
repr() puts out round-trip through the exec statement and eval() functions.
This isn't always possible, but that's the difference between the two.

Both repr() and str() will use the other entry point if their prefered
magic method isn't availible.

John Roth

 

[George Kinney]

Hi,
I have read others' code for study, and found one built-in function
"__repr__". Could anyone give me an simple example for explaining
"when and how" to use it.

The customary use of __repr__ is for it to return a string that can be
passed to eval()
and re-create the object. So for a class 'foo' that takes one string in its
__init__, __repr__
might return "foo('astring')".