Macro impl_struct

macro_rules! impl_struct {
    ( $($macro_params:tt)* ) => { ... };
}

For declaring an anonymous structural type,this expands to an impl Trait.

To construct an anonymous struct you can to use the make_struct macro.

To declare a trait aliasing multiple accessor traits,you can use the structural_alias macro.

Non-accessor bounds

You can add non-accessor bounds by listing them before fields, then separating them from the fields with ;.

Example: impl_struct!{ Clone + Debug; foo:u32, bar:u64 }

Access modifiers

Fields can optionally be prefixed with these access modifiers to specify which accessor traits are required for the field:

-ref: Requires the GetField trait,with shared access.

-mut: Requires the GetFieldMut trait,with mutable access.

-move: Requires the IntoField trait,with shared and by-balue access.

-mut move: Requires the IntoFieldMut trait,with mutable and by-value access.

If none is specified,then the IntoFieldMut trait will be required for that field, with shared,mutable,and by value access to the field.

Example

This demonstrates impl_struct with non-accessor bounds.

use structural::{fp,impl_struct,make_struct,StructuralExt};

fn into_hi_ho_fields(
    this: impl_struct!{ Clone; hi:u32, ho:String }
)-> (u32,String) {
    (
        this.clone().into_field(fp!(hi)),
        this.into_field(fp!(ho)),
    )
}

assert_eq!(
    into_hi_ho_fields(make_struct!{
        #![derive(Clone)]

        hi: 99,
        ho: "what".into(),
    }),
    (99,"what".to_string())
);

Example

This demonstrates the field access modifiers. In this case the fields are read only.

use structural::{fp,impl_struct,make_struct,StructuralExt};

fn into_colors(
    mut this: u32,
)-> impl_struct!{ ref red:u8, ref green:u8, ref blue:u8, ref alpha:u8 } {
    make_struct!(
        red  :this as u8,
        green:(this>>8) as u8,
        blue :(this>>16) as u8,
        alpha:(this>>24) as u8,
    )
}

let colors = into_colors(0x40_30_20_10);
assert_eq!( colors.field_(fp!(red)), &0x10 );
assert_eq!( colors.field_(fp!(green)), &0x20 );
assert_eq!( colors.field_(fp!(blue)), &0x30 );
assert_eq!( colors.field_(fp!(alpha)), &0x40 );