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[refs]

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branches/try/doc/tutorial.md

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When an enum is C-like, you can apply the `as` cast operator to
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convert it to its discriminator value as an `int`.
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<a name="single_variant_enum"></a>
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There is a special case for enums with a single variant, which are
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sometimes called "newtype-style enums" (after Haskell's "newtype"
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feature). These are used to define new types in such a way that the
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new name is not just a synonym for an existing type, but its own
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distinct type: `type` creates a structural synonym, while this form of
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`enum` creates a nominal synonym. If you say:
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~~~~
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enum GizmoId = int;
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~~~~
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That is a shorthand for this:
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~~~~
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enum GizmoId { GizmoId(int) }
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~~~~
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You can extract the contents of such an enum type with the
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dereference (`*`) unary operator:
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~~~~
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# enum GizmoId = int;
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let my_gizmo_id: GizmoId = GizmoId(10);
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let id_int: int = *my_gizmo_id;
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~~~~
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Types like this can be useful to differentiate between data that have
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the same type but must be used in different ways.
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~~~~
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enum Inches = int;
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enum Centimeters = int;
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~~~~
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The above definitions allow for a simple way for programs to avoid
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confusing numbers that correspond to different units.
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For enum types with multiple variants, destructuring is the only way to
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get at their contents. All variant constructors can be used as
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patterns, as in this definition of `area`:
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## Tuple structs
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Rust also has _nominal tuples_, which behave like both structs and tuples,
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except that nominal tuple types have names
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(so `Foo(1, 2)` has a different type from `Bar(1, 2)`),
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and nominal tuple types' _fields_ do not have names.
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Rust also has _tuple structs_, which behave like both structs and tuples,
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except that, unlike tuples, tuple structs have names (so `Foo(1, 2)` has a
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different type from `Bar(1, 2)`), and tuple structs' _fields_ do not have
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names.
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For example:
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~~~~
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}
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~~~~
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<a name="newtype"></a>
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There is a special case for tuple structs with a single field, which are
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sometimes called "newtypes" (after Haskell's "newtype" feature). These are
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used to define new types in such a way that the new name is not just a
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synonym for an existing type but is rather its own distinct type.
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~~~~
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struct GizmoId(int);
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~~~~
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For convenience, you can extract the contents of such a struct with the
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dereference (`*`) unary operator:
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~~~~
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# struct GizmoId(int);
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let my_gizmo_id: GizmoId = GizmoId(10);
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let id_int: int = *my_gizmo_id;
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~~~~
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Types like this can be useful to differentiate between data that have
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the same type but must be used in different ways.
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~~~~
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struct Inches(int);
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struct Centimeters(int);
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~~~~
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The above definitions allow for a simple way for programs to avoid
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confusing numbers that correspond to different units.
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# Functions
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We've already seen several function definitions. Like all other static
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pub mod farm {
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# pub type Chicken = int;
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# type Cow = int;
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# enum Human = int;
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# struct Human(int);
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# impl Human { fn rest(&self) { } }
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# pub fn make_me_a_farm() -> Farm { Farm { chickens: ~[], cows: ~[], farmer: Human(0) } }
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pub struct Farm {

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