bzrlib.decorators : API documentation

Function	only_raises	Make a decorator that will only allow the given error classes to be
Function	use_fast_decorators	Change the default decorators to be fast loading ones.
Function	use_pretty_decorators	Change the default decorators to be pretty ones.
Function	cachedproperty	A decorator for methods that makes them properties with their return
Function	_get_parameters	Recreate the parameters for a function using introspection.
Function	_pretty_needs_read_lock	Decorate unbound to take out and release a read lock.
Function	_fast_needs_read_lock	Decorate unbound to take out and release a read lock.
Function	_pretty_needs_write_lock	Decorate unbound to take out and release a write lock.
Function	_fast_needs_write_lock	Decorate unbound to take out and release a write lock.
Class	_CachedPropertyForAttr	Undocumented
Class	_CachedProperty	Undocumented

def _get_parameters(func):

Recreate the parameters for a function using introspection.

:return: (function_params, calling_params, default_values)
    function_params: is a string representing the parameters of the
        function. (such as "a, b, c=None, d=1")
        This is used in the function declaration.
    calling_params: is another string representing how you would call the
        function with the correct parameters. (such as "a, b, c=c, d=d")
        Assuming you used function_params in the function declaration, this
        is the parameters to put in the function call.
    default_values_block: a dict with the default values to be passed as
        the scope for the 'exec' statement.

    For example:

    def wrapper(%(function_params)s):
        return original(%(calling_params)s)

def _pretty_needs_read_lock(unbound):

Decorate unbound to take out and release a read lock.

This decorator can be applied to methods of any class with lock_read() and
unlock() methods.

Typical usage:

class Branch(...):
    @needs_read_lock
    def branch_method(self, ...):
        stuff

def _fast_needs_read_lock(unbound):

Decorate unbound to take out and release a read lock.

This decorator can be applied to methods of any class with lock_read() and
unlock() methods.

Typical usage:

class Branch(...):
    @needs_read_lock
    def branch_method(self, ...):
        stuff

def _pretty_needs_write_lock(unbound):

Decorate unbound to take out and release a write lock.

def _fast_needs_write_lock(unbound):

Decorate unbound to take out and release a write lock.

def only_raises(*errors):

Make a decorator that will only allow the given error classes to be raised. All other errors will be logged and then discarded.

Typical use is something like:

@only_raises(LockNotHeld, LockBroken)
def unlock(self):
    # etc

def use_fast_decorators():

Change the default decorators to be fast loading ones.

The alternative is to have decorators that do more work to produce nice-looking decorated functions, but this slows startup time.

def use_pretty_decorators():

Change the default decorators to be pretty ones.

def cachedproperty(attrname_or_fn):

A decorator for methods that makes them properties with their return value cached.

The value is cached on the instance, using the attribute name provided.

If you don't provide a name, the mangled name of the property is used.

>>> class CachedPropertyTest(object):
...
...     @cachedproperty('_foo_cache')
...     def foo(self):
...         print 'foo computed'
...         return 23
...
...     @cachedproperty
...     def bar(self):
...         print 'bar computed'
...         return 69

>>> cpt = CachedPropertyTest()
>>> getattr(cpt, '_foo_cache', None) is None
True
>>> cpt.foo
foo computed
23
>>> cpt.foo
23
>>> cpt._foo_cache
23
>>> cpt.bar
bar computed
69
>>> cpt._bar_cached_value
69

b.decorators : module documentation