try_open_existing()

static bool xtd::threading::event_wait_handle::try_open_existing ( const string &  name, event_wait_handle &  result  )

staticnoexcept

Opens the specified named synchronization event, if it already exists, and returns a value that indicates whether the operation succeeded.

Parameters

name

The name of the synchronization object to be opened and shared with other processes. The name is case-sensitive. The backslash character () is reserved and may only be used to specify a namespace. For more information on namespaces, see the remarks section. There may be further restrictions on the name depending on the operating system. For example, on Unix-based operating systems, the name after excluding the namespace must be a valid file name.

result

When this method returns, contains a The xtd::threading::event_wait_handle object that represents the named synchronization event if the call succeeded, or null if the call failed. This parameter is treated as uninitialized.

Returns

true if the named synchronization event was opened successfully; otherwise, false. In some cases, false may be returned for invalid names.

Exceptions

xtd::argument_exception	name is an empty string.
xtd::io::io_exception	name is invalid. This can be for various reasons, including some restrictions that may be placed by the operating system, such as an unknown prefix or invalid characters. Note that the name and common prefixes "Global\" and "Local" are case-sensitive. For some invalid names, the method may return false instead. -or- There was some other error. The HResult property may provide more information.
xtd::io::path_too_long_exception	The name is too long. Length restrictions may depend on the operating system or configuration.

Remarks

The name may be prefixed with Global\ or Local\ to specify a namespace. When the Global namespace is specified, the synchronization object may be shared with any processes on the system. When the Local namespace is specified, which is also the default when no namespace is specified, the synchronization object may be shared with processes in the same session. On Windows, a session is a login session, and services typically run in a different non-interactive session. On Unix-like operating systems, each shell has its own session. Session-local synchronization objects may be appropriate for synchronizing between processes with a parent/child relationship where they all run in the same session.

If a synchronization object of the requested type exists in the namespace, the existing synchronization object is opened. If a synchronization object does not exist in the namespace, or a synchronization object of a different type exists in the namespace, false is returned.

To create the system event when it does not already exist, use one of the xtd::threading::event_wait_handle constructors that has a name parameter.

If you are uncertain whether a named synchronization event exists, use this method overload instead of the xtd::threading::event_xait_handle::open_existing(xtd::uttring) method overload, which throws an exception if the synchronization event does not exist.

Multiple calls to this method that use the same value for name do not necessarily return the same xtd::threading::event_wait_handle object, even though the objects that are returned represent the same named system event.