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live.observer

Monitor changes in Live objects

Description

The live.observer object is used to listen to changes in the values of properties of Live objects. This object works in conjunction with the live.path object, which sends id nn messages into the right inlet of live.observer.

After an object id and property is specified, its value is sent out the left outlet. From this moment on, the value is sent on each change of the property ('notification') as well as in response to bang messages.

The left outlet is reserved for value messages, all other output is sent to the right outlet.

Not all properties can be observed, please consult the Live Object Model to see which can. Also, it is not possible to modify the live set from a notification, i.e. while you are receiving a value message spontaneously sent by a live.observer 's outlet.

Besides properties, it is also possible to observer children of Live objects. Their values are object ids or lists of them.

Arguments

Name Type Opt Description
property symbol opt Specify a property or child name as argument to live.observer.

Inlets

Name Description
Left inlet Gets all command messages described below.
Right inlet Gets object id message id nn to select the object to operate upon. In response to the id message, the current value of the property, if a property was already selected, is sent out the left outlet.
id 0 means no object, i.e. all messages to the left inlet are ignored, which is also the initial state.

Outlets

Name Description
Left outlet Sends the current value of the selected property of the selected object. The value type depends on the property, as described in the Live Object Model, and may be int, float, symbol, id nn or lists of ids.
Right outlet Sends responses to getproperty, gettype, getid.

Messages

bla list-property [symbol]
 Arguments:
list-property the name of a list property of the current object

Operation:
Sends the list of values of given property of the current object.

Remark:
Not all properties can be set.
The types of the properties are given in the Live Object Model.

Outlet Output Example
left value 1 ... value n foo bar
property property [symbol]
 Arguments:
property the name of a property of the current object

Operation:
Selects the property to be observed. Outputs the current value to the left outlet if a proper Live object is selected.

Remark:
Not all properties can be observed.
The types of the properties are given in the Live Object Model.

Outlet Output Example
left value 3.1415926
property child [symbol]
 Arguments:
child the name of a child of the current object

Operation:
Selects the child id to be observed. Outputs the id (or "id 0") to the left outlet if the selected Live object has such a child.

Remark:
Not all children can be observed.

Outlet Output Example
left id nn id 17
property list-child [symbol]
 Arguments:
child the name of a child list of the current object

Operation:
Selects the child list to be observed. Outputs the id list (or nothing) to the left outlet if the selected Live object has such a list child.

Remark:
Not all child lists can be observed.

Outlet Output Example
left id nn ... id mm id 4 id 5
getproperty Operation:
Sends the name of the selected property (or child resp. list-child) out the right outlet.

Outlet Output Example
right property property or
property child 		property name or
property selected_track
gettype Operation:
Sends the type of currently observed property or child to the right outlet. The types of the properties and children are given in the Live Object Model.

For list-children it just sends type tuple, w/o further type information.
Outlet Output Example
right type property-type or
type object-type 		type int or
type Track
getid Operation:
Sends the id of the currently observed Live object to the right outlet.

Outlet Output Example
right id nn id 20
bang Operation:
Sends current value of selected property of current object to the left outlet. Does nothing if no property or no Live object is selected or if they don't match.

Outlet Output Example
left value Drums
id nn Operation:
Sets the current object. The message has the same effect if sent to both the right or the left inlet. For clarity it is suggested to always use the right inlet to supply the object id.

- no output -

Information for box attributes common to all objects

Inspector

Persistence: The live.observer object has a special entry in its inspector labelled "Use Persistent Mapping". This setting, when enabled, causes the id associated with the object to persist when the Live document is saved and restored, and when the Max Device is moved between the Live application and the Max editor, or within the Live Set. Beginning in Live 8.2.2, Live API ids remain persistent between launches of Live, which in conjunction with the Persistence feature of live.object, live.observer and live.remote~, makes it possible to create simpler devices which retain their association with elements in the Live user interface.

Examples

See Also

Name Description
Live API Overview
Live Object Model
live.path Navigate to objects in the Live application
live.object Perform operations on Live objects
live.remote~ Realtime control of device parameters
Using the Live API Creating Devices that use the Live API
The LiveAPI JavaScript Object (jsliveapi) The LiveAPI Object