Method to be used as a function decorator. ![]() The passed in callback is returned from the function, allowing this Unlike the other methods, callbacks added this way cannot suppressĮxceptions (as they are never passed the exception details). callback ( callback, /, * args, ** kwds ) ¶Īccepts an arbitrary callback function and arguments and adds it to The passed in object is returned from the function, allowing this Same way context manager _exit_() methods can. _exit_() method and adds it directly to the callback stack.īy returning true values, these callbacks can suppress exceptions the It is a callback with the same signature as a context manager’s If passed an object that is not a context manager, this method assumes Part of an _enter_() implementation with a context manager’s own push ( exit ) ¶Īdds a context manager’s _exit_() method to the callback stack.Īs _enter_ is not invoked, this method can be used to cover It provides a suitableįoundation for higher level context managers that manipulate the exitĬhanged in version 3.11: Raises TypeError instead of AttributeError if cm This is a relatively low level API that takes care of the details ofĬorrectly unwinding the stack of exit callbacks. This evenĮxtends to exception handling - if an inner callback suppresses or replacesĪn exception, then outer callbacks will be passed arguments based on that Statements had been used with the registered set of callbacks. Registration, this ends up behaving as if multiple nested with Since registered callbacks are invoked in the reverse order of Resources in their _init_ method (such as file objects) can be This stack model is used so that context managers that acquire their Invoked implicitly when the context stack instance is garbage collected. Reverse order when the instance is closed (either explicitly or implicitlyĪt the end of a with statement). The _enter_() method returns the ExitStack instance, andĮach instance maintains a stack of registered callbacks that are called in With ExitStack () as stack : files = # All opened files will automatically be closed at the end of # the with statement, even if attempts to open files later # in the list raise an exception Managers support multiple invocations in order to be used as decorators). When used as a decorator, a new generator instance is implicitly created onĮach function call (this allows the otherwise “one-shot” context managersĬreated by contextmanager() to meet the requirement that context It creates can be used as decorators as well as in with statements. ![]() Immediately following the with statement.Ĭontextmanager() uses ContextDecorator so the context managers The exception has been handled, and execution will resume with the statement Generator context manager will indicate to the with statement that Suppress it entirely), the generator must reraise that exception. Trapped merely in order to log it or to perform some action (rather than to The error (if any), or ensure that some cleanup takes place. Generator at the point where the yield occurred. If an unhandled exception occurs in the block, it is reraised inside the The generator is then resumed after the block is exited. ![]() The targets in the with statement’s as clause, if any.Īt the point where the generator yields, the block nested in the with This iterator must yield exactly one value, which will be bound to The function being decorated must return a generator-iterator whenĬalled. # even if code in the block raises an exception # Resource is released at the end of this block. with managed_resource ( timeout = 3600 ) as resource.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |