Optional

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Object Hierarchy:

Description:

Content:

Properties:

• public bool is_present { get; }
  Whether or not there is a value present.
• public G value { get; }
  The value held by this optional.
• public Type value_type { get; }
  The type of the value.

Creation methods:

• public Optional ()
• public Optional.empty ()
  Creates an empty optional instance.
• public Optional.of (owned G value)
  Creates an optional instance with the given value present.

Methods:

• public Optional<G> filter (Predicate<G> pred)
  If a value is present and matches the given predicate, returns an optional containing the value, otherwise returns an empty optional.
• public void if_present (Func<G> consumer)
  If a value is present, performs the given consumer function with the value.
• public Optional<A> map<A> (MapFunc<Optional<A>,G> mapper)
  If a value is present, performs the mapper function with the value, and returns the result. Otherwise returns an empty optional.
• public G or_else (G other)
  If a value is present, returns the value, otherwise returns the given other.
• public G or_else_fail ()
  If a value is present, returns the value, otherwise fails with GLib.error.
• public G or_else_get (SupplyFunc<G> supplier)
  If a value is present, returns the value, otherwise returns the result produced by the supply function.
• public G or_else_throw (SupplyFunc<Error>? error_supplier = null) throws Error
  If a value is present, returns the value, otherwise throws an error produced by the supply function -- or an OptionalError.NOT_PRESENT error if the function is not specified.
• public string to_string ()

Inherited Members: