Struct Attr 

pub struct Attr<M: Model> { /* private fields */ }

An attribute of a single device, together with the last value written to it, which Tango keeps aside from the model, and its configuration on that device. Its definition is shared the way that of a Command is.

Implementations

impl<M: Model> Attr<M>

pub fn name(&self) -> &str

The name of that attribute, as its definition gave it.

pub fn config(&self) -> AttrConfig

The configuration of that attribute on its device.

pub fn is_memorized(&self) -> bool

Whether that attribute is memorized, see AttrMemorized.

pub fn info(&self) -> Result<AttrInfo>

What a client is told of that attribute: what it may read and change of its configuration, and what its definition advertises of its data.

A definition advertising neither a kind nor a format, which only one built out of a raw handler and given neither can be, has nothing to tell a client of its data and is answered with an error rather than with a guess.

An attribute whose configuration could not be applied is described all the same, with what could be, so that a client can still see what it is configured with.

TODO: AttrMode::ReadWithWrite cannot be derived from the handlers, the write attribute it is paired with having to be named; it needs its own definition.

pub fn push_history( &self, read: Result<AttrRead<Value>>, valid_for: Option<Duration>, ) -> Result<()>

Record that reading in the history of that attribute, the oldest one being dropped when the history is full, see Self::set_history_depth. A reading that failed is recorded as well, as the error it failed with.

The latest reading is what a read from the cache is answered with, for that long when given a validity, after which the device is read again, or a read from the cache alone fails as outdated; without one, it answers until the next is recorded.

The reading must have a read value, so an attribute that cannot be read records none, and be of a valid quality for the State and the Status, their commands answering with the value alone. The write value is merged into it as for an event, see Dev::push_attr_event.

pub fn history(&self, max: usize) -> Vec<RecordedResult<AttrRead<Value>>>

The latest readings recorded in the history of that attribute, oldest first and at most max of them, see Self::push_history.

pub fn clear_history(&self)

Forget every reading recorded in the history of that attribute, so that a read from the cache finds none.

pub fn history_depth(&self) -> usize

How many readings the history of that attribute keeps at most.

pub fn set_history_depth(&self, depth: usize)

Set how many readings the history of that attribute keeps at most, the oldest ones beyond that being dropped now. A depth of zero records nothing.