Properties — WirePlumber 0.5.17 documentation

# Properties

`Properties` is a string-to-string dictionary, the type used throughout WirePlumber for PipeWire object properties, event properties and so on. It binds the WpProperties C API.

Most of the time scripts obtain a `Properties` object from somewhere else — `node.properties`, `Event.get_properties()`, `Conf.get_section_as_properties()` — rather than constructing one.

## Accessing values

Values are read and written with the normal Lua indexing syntax. Reading a key that is not set returns nil.

    local props = node.properties

    local name = props ["node.name"]
    props ["my.custom.property"] = "value"

Because a `Properties` object holds strings, the typed accessors below are provided for the common cases of reading a value that represents a boolean or a number.

Properties(value)

  Constructs a new `Properties` object.

  Parameters:

    value -- a Lua table of string keys and values to initialize from, or another `Properties` object to copy, or nothing for an empty object

  Returns:

    the new properties object

  Return type:

    Properties

Properties.get_boolean(self, key)

  Returns the value of key interpreted as a boolean.

  Parameters:

    key (string) -- the key to look up

  Returns:

    the value, or nil if the key is not set

  Return type:

    boolean

Properties.get_int(self, key)

  Returns the value of key interpreted as an integer.

  Parameters:

    key (string) -- the key to look up

  Returns:

    the value, or nil if the key is not set

  Return type:

    integer

Properties.get_float(self, key)

  Returns the value of key interpreted as a floating point number.

  Parameters:

    key (string) -- the key to look up

  Returns:

    the value, or nil if the key is not set

  Return type:

    number

Properties.get_count(self)

  Binds `wp_properties_get_count()`

  Returns:

    the number of properties in the object

  Return type:

    integer

Properties.copy(self)

  Binds `wp_properties_copy()`

  Returns an independent copy of the properties, which can be modified without affecting the original.

  Returns:

    a copy of the properties

  Return type:

    Properties

Properties.parse(self)

  Converts the properties into a plain Lua table of string keys and values.

  Note

  This creates a full copy. Prefer indexing the `Properties` object directly when you only need a few keys; the shipped scripts were converted to do so because building a table for every object turned out to be measurably expensive.

  Returns:

    a table with the contents of the properties

  Return type:

    table