PEP: Adding decorators for everything

[tharaka]

Hi Guys,

This is an idea for a PEP.

How would you guys feel about adding decorator support for
"everything"? Currently, only functions and method are supported.

For example:

@GuardedClass
class Foo:
@Transient
a = 'a transient field, ignored when serializing'

@Const
PI = 22.0 / 7

@TypeSafe(int)
count = 10

...



instead of:
class Foo:
a = Transient('a transient field, ignored when serializing')

PI = Const(22.0 / 7)

count = TypeSafe(int)(10)

...
Foo = GuardedClass(Foo)


I mean, this would pave the way for a declarative style of programming
(in a more intuitive way).

It would also be better if multiple decorators could be written on the
same line. E.g.:
@A @B(x, y) @C
def foo(): ...

instead of
@A
@B(x, y)
@C
def foo(): ...

(The function definition should start on the next line though).


Suggestions, Comments, flames, anybody?


Cheers!

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Re: Fire event when variable is Set/Get

[tharaka]

You are in luck because Python has "Properties" just like .NET.

For details lookup the documentation of the built-in function
property(). I'll just paste it here:


property( [fget[, fset[, fdel[, doc)

Return a property attribute for new-style classes (classes that derive
from object).
fget is a function for getting an attribute value, likewise fset is a
function for setting, and fdel a function for del'ing, an attribute.
Typical use is to define a managed attribute x:


class C(object):
def getx(self): return self.__x
def setx(self, value): self.__x = value
def delx(self): del self.__x
x = property(getx, setx, delx, "I'm the 'x' property.")


... now u can use x like any variable and, python will get & set it
through the appropriate methods. Hope this answers your question.

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