Struct Layer 

pub struct Layer {
    pub allowed: Option<Vec<String>>,
    pub mode: Option<Mode>,
    pub denied: Option<Vec<String>>,
    pub user_may_extend: Option<bool>,
    pub confirm_each_write_back: Option<bool>,
    pub notify: Option<Notify>,
}

One layer’s contribution. Every field is optional, and None means the layer says nothing about it rather than saying no.

Fields

allowed: Option<Vec<String>>

Extensions this layer permits.

mode: Option<Mode>

Whether allowed stands alone or adds. Defaults to Mode::Replace deliberately. Concept 10 names the silent hole: an administrator who writes a list expecting it to be exhaustive and gets it unioned with the defaults has permitted things they never listed, and never finds out. Appending is the surprising reading, so it is the one that has to be asked for.

denied: Option<Vec<String>>

Extensions this layer refuses. Always wins, everywhere.

user_may_extend: Option<bool>

Whether the user’s own configuration is honoured at all. Only a policy layer setting this to false has any effect, and what it suppresses is Origin::Configuration — not another policy layer, which is administered too.

confirm_each_write_back: Option<bool>

Whether every write-back is confirmed, rather than only the session close. Concept 6.2 keeps this off by default: a repack is atomic and unremarkable, and a prompt on every save is friction for everyone who is not archiving.

notify: Option<Notify>

How much the tool says without being asked. See Notify.

Implementations

impl Layer

pub fn says_nothing(&self) -> bool

Whether this layer sets nothing at all.

A file that parses and holds no key is a layer that exists and has no opinion, which is different from one that is not there — but not different in any way a decision can see. What it changes is whether Effective::managed should call the machine administered, and it should not: see the note there.

allowed = [] is not this. An empty list is a layer permitting nothing, which says a great deal.

Trait Implementations

impl Clone for Layer

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Layer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Layer

fn default() -> Self

Returns the “default value” for a type.