This is great feedback…. And yet another
way we could consider doing this would be something whacky with metaclasses
where we had an “attribute-aware” metaclass or something like that…
But it demonstrates the difficulty in adding support for features like this and
the reason we need to tread lightly here.
From:
[EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Eric Larson
Sent: Monday, March 27, 2006 9:11
AM
To: Discussion
of IronPython
Subject: Re: [IronPython] .NET
Attributes
On the topic of
decorators and integrating with .NET, it seems that in order to keep IronPython
as close to CPython, it would be a good idea to consider adding .NET specific
pieces as a "library" instead of an addition to the language. That
way people could write python code that works in IronPython and CPython equally
well without changing radically how the code is written. For example, if I
wanted to make a class serializable, it seems logical to inherit from some
serializable base class.
from clr.netisms import IPSerializable
class MyClass(IPSerializable):
....
This may be an obvious solution, but it seems to make more sense to add
IronPython specific libraries to help integrate with .NET than to pollute the
language. I mention this because one of the great things about Python is the
"batteries included" mentality. There are many great libraries that
would be excellent to run using IronPython (ZODB for example) that may conflict
if the language gets massaged to fit into .NET perfectly. Often times writing
to the lowest common denominator can be bad (SQL portability for example), but
I believe in the case of Python, whatever can be done to work with the massive
amount of libraries will be the most beneficial.
I apologize if this is already addressed. I am thinking about issues such as
these from a python programmer's perspective.
Great work!
Eric
On 3/27/06, Dino
Viehland <[EMAIL PROTECTED]>
wrote:
This is a tough problem... There are two issues
here. But the executive summary here is I'd say the earliest you
should *expect* to see this is 1.1, but if (somehow) we end up with some extra
time we might have something in the 1.0 timeframe (but don't hold your breath!).
The first issue here is that when your code gets compiled we don't create what
are truly .NET classes. Let's forget about old-style classes for a
second (as those are REALLY not .NET classes, and never will be) and instead
focus on new-style classes.
When you define a class we'll see if anyone else has inherited from the same
set of base-types (including .NET interfaces). If someone has then
we'll use that class instead of creating a new class. If they
haven't we'll derive a new class from your base-class set, overriding all of
the virtual methods, and creating some new fields like __dict__ and
__class__. Those fields allow us to both allow you to change the
type of your classes at runtime as well as attach new properties to
instances. They also allow us to create a limited number of CLR
types (which aren't garbage collected) which means long-running programs
creating lots of types don't leak.
In the end there's not really anything good for us to attach the attributes
to. To get that we'd need to move to a more static-compilation model
while at the same time retaining the ability to do all the great dynamic stuff
with Python. It's a hard problem and one that we simply haven't
solved yet.
The second problem is also just as tough, but it's completely different. How
do you even express an attribute on a class? There's no Python
syntax for this so we'd have to add something new. It'd be great if
we could use decorators here, but they don't apply to classes. So
maybe that's something like __attributes__ = [Serializable, ...] or something
along those lines but it's not clear what's the best way to go here...
Do you want to help develop Dynamic languages on CLR? (http://members.microsoft.com/careers/search/details.aspx?JobID=6D4754DE-11F0-45DF-8B78-DC1B43134038
)
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]
] On Behalf Of Andrzej Krzywda
Sent: Monday, March 27, 2006 4:55 AM
To: users@lists.ironpython.com
Subject: [IronPython] .NET Attributes
Hi,
When there will be support for .NET Attributes in IronPython?
Is there any way currently to mark my class as Serializable?
--
Andrzej
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