spir wrote:
On Thu, 04 Mar 2010 09:22:52 -0500
Dave Angel <da...@ieee.org> wrote:
Still, slots are important, because I suspect
that's how built-ins are structured, to make the objects so small.
Sure, one cannot alter their structure. Not even of a direct instance of
<object>:
o = object()
o.n=1
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'object' object has no attribute 'n'
Now, some objects, probably most of the built-ins, are not extensible.
You can't add new methods, or alter the behavior much.
This applies to any attr, not only methods, also plain "information":
s = "abc"
s.n=1
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'str' object has no attribute 'n'
Other objects,
such as instances of a class you write, are totally and very flexible.
conceptually this is equivalent to have no __slots__ slot. Or mayby they could
be implemented using structs (which values would be pointers), instead of
dicts. A struct is like a fixed record, as opposed to a dict. What do you
think? On the implementation side, this would be much simpler, lighter, and
more efficient.
Oh, this gives me an idea... (to implement so-called "value objects").
Denis
having not played much with slots, my model is quite weak there. But I
figure the dictionary is in the implementation structure, along with a
flag saying that it's readonly. Each item of such a dictionary would be
an index into the fixed table in the object. Like a struct, as you say,
except that in C, there's no need to know the names of the fields at run
time.
DaveA
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