On 17 kesä, 10:47, voltron <[EMAIL PROTECTED]> wrote:
> I am having problems using decorators with controllers. In a test
> controller:
[clip]
> I have to pass "self" to the function passed to the decorator somehow,
> what would be the best way to do this? I want the decorator to carry
> out a few things before calling the controller function its
> decorating.
A generic decorator factory looks like this
def dec(whatever_parameter):
def decorator(func):
def wrapper(*a, **kw):
print whatever_parameter, a, kw
return func(*a, **kw)
return wrapper
return decorator
So, consider
class Foo(object):
@dec("calling foo")
def foo(self):
print "foo"
@dec("calling bar")
def bar(self, k, m):
print "bar", k, m
This is *equivalent* to (and so for all decorators, the @ is just
syntax sugar)
class Foo(object):
def foo(self):
print "foo"
foo = dec("calling foo")(foo)
def bar(self, k, m):
print "bar", k, m
bar = dec("calling bar")(bar)
That is, both "dec" and "decorator" are run already when the module
is imported. The "decorator" should return a function that is fit
to be used as a class method, i.e. accepts "self" as the first
parameter.
Now,
a = Foo()
a.foo()
a.bar(5, m=6)
prints
calling foo (<__main__.Foo object at 0xb7cf74ac>,) {}
foo
calling bar (<__main__.Foo object at 0xb7cf74ac>, 5) {'m': 6}
bar 5 6
That is, the wrapper is run every time either foo or bar is called.
Note that 'self' is the first parameter to wrapper (the first entry in
*a),
since it is called as a class method. Keyword parameters go to the
**kw dict.
So if you want to "pass" self to the wrapper explicitly, you can write
the wrapper for example like
def wrapper(self, *a, **kw):
# do something with self
return func(self, *a, **kw)
Hope this clarifies decorators a bit.
--
Pauli Virtanen
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