wand.resource
— Global resource management¶
There is the global resource to manage in MagickWand API. This module implements automatic global resource management through reference counting.
-
wand.resource.
genesis
()¶ Instantiates the MagickWand API.
Warning
Don’t call this function directly. Use
increment_refcount()
anddecrement_refcount()
functions instead.
-
wand.resource.
terminus
()¶ Cleans up the MagickWand API.
Warning
Don’t call this function directly. Use
increment_refcount()
anddecrement_refcount()
functions instead.
-
wand.resource.
increment_refcount
()¶ Increments the
reference_count
and instantiates the MagickWand API if it is the first use.
-
wand.resource.
decrement_refcount
()¶ Decrements the
reference_count
and cleans up the MagickWand API if it will be no more used.
-
class
wand.resource.
Resource
¶ Abstract base class for MagickWand object that requires resource management. Its all subclasses manage the resource semiautomatically and support
with
statement as well:with Resource() as resource: # use the resource... pass
It doesn’t implement constructor by itself, so subclasses should implement it. Every constructor should assign the pointer of its resource data into
resource
attribute inside ofwith
allocate()
context. For example:class Pizza(Resource): '''My pizza yummy.''' def __init__(self): with self.allocate(): self.resource = library.NewPizza()
New in version 0.1.2.
-
allocate
(**kwds)¶ Allocates the memory for the resource explicitly. Its subclasses should assign the created resource into
resource
attribute inside of this context. For example:with resource.allocate(): resource.resource = library.NewResource()
-
c_clear_exception
= NotImplemented¶ (
ctypes.CFUNCTYPE
) Thectypes
function that clears an exception of theresource
.Note
It is an abstract attribute that has to be implemented in the subclass.
-
c_destroy_resource
= NotImplemented¶ (
ctypes.CFUNCTYPE
) Thectypes
function that destroys theresource
.Note
It is an abstract attribute that has to be implemented in the subclass.
-
c_get_exception
= NotImplemented¶ (
ctypes.CFUNCTYPE
) Thectypes
function that gets an exception from theresource
.Note
It is an abstract attribute that has to be implemented in the subclass.
-
c_is_resource
= NotImplemented¶ (
ctypes.CFUNCTYPE
) Thectypes
predicate function that returns whether the given pointer (that contains a resource data usuaully) is a valid resource.Note
It is an abstract attribute that has to be implemented in the subclass.
-
destroy
()¶ Cleans up the resource explicitly. If you use the resource in
with
statement, it was called implicitly so have not to call it.
-
get_exception
()¶ Gets a current exception instance.
Returns: a current exception. it can be None
as well if any errors aren’t occurredReturn type: wand.exceptions.WandException
-
raise_exception
(stacklevel=1)¶ Raises an exception or warning if it has occurred.
-
resource
¶ Internal pointer to the resource instance. It may raise
DestroyedResourceError
when the resource has destroyed already.
-
-
exception
wand.resource.
DestroyedResourceError
¶ An error that rises when some code tries access to an already destroyed resource.
Changed in version 0.3.0: It becomes a subtype of
wand.exceptions.WandException
.