Struct Context 

pub struct Context<'a> {
    pub step: &'a str,
    pub runner: &'a Runner,
    pub before: Reader<'a>,
    pub built: Option<Reader<'a>>,
    pub whole: Reader<'a>,
    pub scene: Option<&'a dyn Scene>,
}

What a step is edited against: its id — what everything it builds is named after — the runner it is run by, which reads the files around its program, the part as it was before it, the part as the step built it when it last ran, if it did, and, for an event, the part as the editor draws it — what a pointer is over, without drawing it again.

Fields

step: &'a str

runner: &'a Runner

before: Reader<'a>

built: Option<Reader<'a>>

whole: Reader<'a>

The part as far as the last run built it: all of it, for a step that picks in the whole part (OperationInfo::picks_whole), whose fields read it here.

scene: Option<&'a dyn Scene>

The part as drawn for picks (see Scene): given with every event an editor passes on, and nothing else.