Function conch_runtime::eval::alternative [−] [src]

pub fn alternative<P: ?Sized, W, E: ?Sized>(
    strict: bool, 
    param: &P, 
    alternative: Option<W>, 
    env: &E, 
    cfg: TildeExpansion
) -> Alternative<W::EvalFuture> where
    P: ParamEval<E, EvalResult = W::EvalResult>,
    W: WordEval<E>,

Constructs future representing a Alternative parameter substitution evaluation.

First, param will be evaluated and if the result is non-empty, or if the result is defined-but-empty and strict = false, then alternative will be evaluated and yielded.

Otherwise, Fields::Zero will be returned (i.e. the value of param).

Note: field splitting will neither be done on the parameter, nor the alternative word.