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Admits

cove_runtime::schema

Trait Admits 

Source 
pub trait Admits {
    // Required method
    fn admits(&self, value: &Value) -> Result<(), Mismatch>;
}
Expand description

Whether a value is one a declared type admits.

This is an extension of HostType rather than an inherent method because the type lives in a crate that has no values to check. Everything it says about which values a type admits is the schema’s; only the walking of a Value is this crate’s.

Required Methods§

Source

fn admits(&self, value: &Value) -> Result<(), Mismatch>

Whether value is one this type admits, and where it stops being one when it is not.

The check follows this type’s own recursion rather than looking only at the outermost constructor, because a shallow check would admit an Array<Int> where an Array<String> was declared and the schema says more than “an array”. HostType::Any admits everything, which is not a hole: it is the type of an operation whose meaning does not depend on which value it was given — the work clock.timeout bounds, the body clock.every repeats — so there is nothing there to check.

HostType::Named is checked by name. Every value carries the qualified type it was built with and a crate::host::ResourceHandle carries the module and kind it was issued for, so the comparison is one the value itself can answer, with no registry to consult and no second lookup on a path every host call takes. What that leaves unchecked is a TypeSchema’s fields: a value calling itself an http.Response is taken at its word about what is inside it. See ADR 0013’s amendment for why that line is drawn there.

Dyn Compatibility§

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§