On 05/22/2015 01:34 PM, Marko Rauhamaa wrote:
Ian Kelly <ian.g.ke...@gmail.com>:
An "object" in Javascript is basically just a collection of
properties. For example:
js> typeof([1, 2, 3])
"object"
js> typeof({a: 1, b: 2, c: 3})
"object"
Here's what happens when you try to access a property on null:
js> null.foo
typein:18:0 TypeError: null has no properties
That's not all that different from Python, where object() returns a
fresh instance at each invocation. However:
>>> object().x = 3
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'object' object has no attribute 'x'
Why are object instances immutable in Python?
# psuedo-code
class object:
__slots__ = ()
class bad_object:
"__slots__ not specified, so automatically gets a __dict__"
class tuple(...) <- object or bad_object? hint: the clue is in the name ;)
__slots__ = ()
If tuple is based on bad_object, it will get a __dict__ and be very-mutable.
In order to have slightly-mutable or immutable objects, the base class has to
not have a __dict__, so object does not.
Mind you, I don't know if that's the reason why it was decided to be like that,
or just a nice consequence of the choice to do it that way.
--
~Ethan~
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