watcher

​
This extension provides support for setting up 'event watchers'.
For example, if you want to allow interested parties to watch for 'update' events, you might have something like this:
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local thing = {}
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​
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thing.watchers = watcher.new('update')
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​
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thing.watch(events)
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	return thing.watchers:watch(events)
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end
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​
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thing.update(value)
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	thing.value = value
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	thing.watchers:notify('update', value)
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end
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Then, your other code could get notifications like so:
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thing.watch({
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	update = function(value) print "New value is "..value end
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})
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Then, whenever thing.update(xxx) is called, the watcher will output "New value is xxx".
API Overview
Functions - API calls offered directly by the extension
​new​
Methods - API calls which can only be made on an object returned by a constructor
​events​
​getCount​
​notify​
​unwatch​
​watch​
API Documentation
Functions
​new​
Signature
cp.watcher.new(...) -> watcher
Type
Function
Description
Constructs a new watcher instance.
Parameters
... - The list of event name strings supported by the watcher.
Returns
a new watcher instance
Methods
​events​
Signature
cp.watcher:events()
Type
Method
Description
Returns a list of the event names supported by this watcher.
Parameters
None
Returns
The table of event names.
​getCount​
Signature
cp.watcher:getCount()
Type
Method
Description
Returns the number of watchers currently registered.
Parameters
None
Returns
The number of watchers.
​notify​
Signature
cp.watcher:notify(type, ...) -> nil
Type
Method
Description
Notifies watchers of the specified event type.
Parameters
type - The event type to notify. Must be one of the supported events.
... - These parameters are passed directly to the event watcher functions.
Returns
Nothing.
​unwatch​
Signature
cp.watcher:unwatch(id) -> boolean
Type
Method
Description
Removes the watchers which were added with the specified ID.
Parameters
id - The unique ID returned from watch.
Returns
true if a watcher with the specified ID exists and was successfully removed.
​watch​
Signature
cp.watcher:watch(events) -> id
Type
Method
Description
Adds a watcher for the specified events.
Parameters
events - A table of functions, one for each event to watch.
Returns
A unique ID that can be passed to unwatch to stop watching.