Re: [Python-ideas] Reprs of classes and functions
On Wed, Feb 25, 2015 at 10:12:03AM +0200, Serhiy Storchaka wrote:
This idea is already casually mentioned, but sank deep into the threads of the discussion. Raise it up.
Currently reprs of classes and functions look as:
int
<class 'int'> int.from_bytes
<built-in method from_bytes of type object at 0x826cf60> open
<built-in function open> import collections collections.Counter
<class 'collections.Counter'> collections.Counter.fromkeys
<bound method Counter.fromkeys of <class 'collections.Counter'>> collections.namedtuple
<function namedtuple at 0xb6fc4adc>
What if change default reprs of classes and functions to just full qualified name __module__ + '.' + __qualname__ (or just __qualname__ if __module__ is builtins)? This will look more neatly. And such reprs are evaluable.
Do you mean like this?
repr(int) => 'int'
repr(int.from_bytes) => 'int.from_bytes'
repr(open) => 'open'
repr(collections.Counter) => 'collections.Counter'
repr(collections.Counter.fromkeys) => 'collections.Counter.fromkeys'
repr(collections.namedtuple) => 'collections.namedtuple'
-1 on that idea.
The suggested repr gives no clue as to what kind of object they are. Are they functions, methods, classes, some kind of Enum-like constant or something special like None? That hurts the usefulness of object reprs at the interactive interpreter. And it leads to weirdness like this:
def spam(x): if not isinstance(x, int): raise TypeError('expected int, got %r' % x)
# current behaviour
spam(int) => TypeError: expected int, got <class 'int'>
# proposed behaviour
spam(int) => TypeError: expected int, got int
As for them being evaluable, I don't think that's terribly useful. Do you have a use-case for that?
I'm not saying that it will never be useful, but I don't think it is useful enough to make up for the loss of human-readable information (the type of the object). Being able to eval(repr(instance)) is sometimes handy, but I don't think eval(repr(type_or_function)) is useful.
-- Steve