#Stack on safe won t open with code generator
#Stack on safe won t open with code code

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 Would if used directly as part of a with statement. These context managers may suppress exceptions just as they normally The return value is the result of the context enter_context ( cm ) ¶Įnters a new context manager and adds its _exit_() method to It provides a suitableįoundation for higher level context managers that manipulate the exit 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).

#Stack on safe won t open with code generator

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.

#Stack on safe won t open with code code

# 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.