Module build

Builders for defining metadata for variant types (enums), and composite types (structs). They are designed to allow only construction of valid definitions.

In most cases we recommend using the scale-info-derive crate to auto generate the builder constructions.

Examples

Generic struct

struct Foo<T> {
    bar: T,
    data: u64,
}

impl<T> TypeInfo for Foo<T>
where
    T: TypeInfo + 'static,
{
    type Identity = Self;

    fn type_info() -> Type {
        Type::builder()
            .path(Path::new("Foo", module_path!()))
            .type_params(type_params!(T))
            .composite(Fields::named()
                .field(|f| f.ty::<T>().name("bar").type_name("T"))
                .field(|f| f.ty::<u64>().name("data").type_name("u64"))
            )
    }
}

Tuple struct

struct Foo(u32, bool);

impl TypeInfo for Foo {
    type Identity = Self;

    fn type_info() -> Type {
        Type::builder()
            .path(Path::new("Foo", module_path!()))
            .composite(Fields::unnamed()
                .field(|f| f.ty::<u32>().type_name("u32"))
                .field(|f| f.ty::<bool>().type_name("bool"))
            )
    }
}

Enum with fields

enum Foo<T>{
    A(T),
    B { f: u32 },
    C,
}

impl<T> TypeInfo for Foo<T>
where
    T: TypeInfo + 'static,
{
    type Identity = Self;

    fn type_info() -> Type {
        Type::builder()
            .path(Path::new("Foo", module_path!()))
               .type_params(type_params!(T))
            .variant(
                Variants::new()
                    .variant("A", |v| v
                        .index(0)
                        .fields(Fields::unnamed().field(|f| f.ty::<T>().type_name("T")))
                    )
                    .variant("B", |v| v
                        .index(1)
                        .fields(Fields::named().field(|f| f.ty::<u32>().name("f").type_name("u32")))
                    )
                    .variant_unit("A", 2)
            )
    }
}

Enum without fields, aka C-style enums.

enum Foo {
    A,
    B,
    C = 33,
}

impl TypeInfo for Foo {
    type Identity = Self;

    fn type_info() -> Type {
        Type::builder()
            .path(Path::new("Foo", module_path!()))
            .variant(
                Variants::new()
                    .variant("A", |v| v.index(1))
                    .variant("B", |v| v.index(2))
                    .variant("C", |v| v.index(33))
            )
    }
}

Modules

field_state

Type states for building a field.

state

State types for type builders which require a Path.

variant_state

State types for the VariantBuilder which requires an index.

Structs

FieldBuilder

Construct a valid Field.

Fields

Provides FieldsBuilder constructors

FieldsBuilder

Build a set of either all named (e.g. for a struct) or all unnamed (e.g. for a tuple struct)

TypeBuilder

Builds a Type

VariantBuilder

Build a Variant.

Variants

Builds a definition of a variant type i.e an enum

Enums

NamedFields

A fields builder only allows named fields (e.g. a struct)

NoFields

A fields builder has no fields (e.g. a unit struct)

UnnamedFields

A fields builder only allows unnamed fields (e.g. a tuple)