EVB::CallbackManager name
name define callback-name
name register callback-name script
name get callback-name
name invoke callback-name substitutions values
Manages a set of callbacks. This can be used by megawidgets and supports script substitution patterns.
The conceptual idea is that the application instantiates a callback
manager and uses define to define
callbacks. As callback scripts are supplied they are inserted
into the callback manager using register.
When it is time to run a callback, invoke
allows you to do so specifying a set of substition keys and the
values to substitute for those keys in the script.
invoke runs callbacks at level 0 using
uplevel #0.
When constructing a manager, supply a single parameter that provides a name for the callback manager object. The special name %AUTO% allocates a unique name for the object for you. Construction returns the name of the object. The following idiom is therefore best used when using %AUTO%:
Defines a callback. Clients can only register callback
scripts for callbacks that have been defined via this
method. Furthermore, only define callbacks can be
invoked without an error
being thrown. Callbacks have names (callback-name).
Registers a script for the
callback callback-name.
If script is empty, the
callback is assumed to have no script.
Returns the script that is registered on the
callback-name. If there is no
script registered, an empty string is returned.
Invokes the callback registered on callback-name.
If the registered script is empty, this is a no-op.
Prior to executing the script, all occurences of
the strings in the list substitutions
are replaced by corresponcing elements in the list
values
This mechanism allows callers to supply information to the callback as desired by that callback.