Macro default_constructor::meta_default_constructor

macro_rules! meta_default_constructor {
    (
        {$($imports: stmt);* $(;)?}
        $($tt: tt)*
    ) => { ... };
    (
        @ty 
        [$func: expr]
        ::$($ty: ident)::*
        ::< $($tt: tt)*
    ) => { ... };
    (
        @ty 
        [$func: expr]
        ::$($ty: ident)::*
        {$($tt: tt)*}
    ) => { ... };
    (
        @ty 
        [$func: expr]
        $($ty: ident)::*
        ::< $($tt: tt)*
    ) => { ... };
    (
        @ty 
        [$func: expr]
        $($ty: ident)::*
        {$($tt: tt)*}
    ) => { ... };
    (
        @generics
        [$func: expr]
        [$($ty: tt)*]
        [$($generics: tt)*]
        ::<$lt: lifetime, $($tt: tt)*
        
    ) => { ... };
    (
        @generics
        [$func: expr]
        [$($ty: tt)*]
        [$($generics: tt)*]
        ::<$lt: lifetime> $($tt: tt)*
        
    ) => { ... };
    (
        @generics
        [$func: expr]
        [$($ty: tt)*]
        [$($generics: tt)*]
        ::<$($gty: ty),* $(,)?>
        $($tt: tt)*
    ) => { ... };
    (
        @fields
        [$func: expr]
        [$($ty: tt)*]
        [$($generics: tt)*]
        {$field: ident: $block: block $(, $($tt: tt)*)?} 
        {$($out_field: ident: $out_expr: expr),*} 
    ) => { ... };
    (
        @fields
        [$func: expr]
        [$($ty: tt)*]
        [$($generics: tt)*]
        {$field: ident: ::$($ty2: ident)::* {$($fields: tt)*} $(, $($tt: tt)*)?} 
        {$($out_field: ident: $out_expr: expr),*} 
    ) => { ... };
    (
        @fields
        [$func: expr]
        [$($ty: tt)*]
        [$($generics: tt)*]
        {$field: ident: $($ty2: ident)::* {$($fields: tt)*} $(, $($tt: tt)*)?} 
        {$($out_field: ident: $out_expr: expr),*} 
    ) => { ... };
    (
        @fields
        [$func: expr]
        [$($ty: tt)*]
        [$($generics: tt)*]
        {$field: ident: @$effect:ident ::$($ty2: ident)::* {$($fields: tt)*} $(, $($tt: tt)*)?} 
        {$($out_field: ident: $out_expr: expr),*} 
    ) => { ... };
    (
        @fields
        [$func: expr]
        [$($ty: tt)*]
        [$($generics: tt)*]
        {$field: ident: @$effect:ident $($ty2: ident)::* {$($fields: tt)*} $(, $($tt: tt)*)?} 
        {$($out_field: ident: $out_expr: expr),*} 
    ) => { ... };
    (
        @fields
        [$func: expr]
        [$($ty: tt)*]
        [$($generics: tt)*]
        {$field: ident: @$effect:ident $expr: expr $(, $($tt: tt)*)?} 
        {$($out_field: ident: $out_expr: expr),*} 
    ) => { ... };
    (
        @fields
        [$func: expr]
        [$($ty: tt)*]
        [$($generics: tt)*]
        {$field: ident: $expr: expr $(, $($tt: tt)*)?} 
        {$($out_field: ident: $out_expr: expr),*} 
    ) => { ... };
    (
        @fields
        [$func: expr]
        [$($ty: tt)*]
        []
        {}
        {$($field: ident: $expr: expr),*} 
    ) => { ... };
    (
        @fields
        [$func: expr]
        [$($ty: tt)*]
        [$($generics: tt)*]
        {}
        {$($field: ident: $expr: expr),*} 
    ) => { ... };
}

The meta macro.

Syntax

meta_default_constructor!(
    // scoped imports, optional, must be in braces `{..}`
    {
        import std::future::Future;
        import rand::prelude::*;
    }
    // conversion function, required
    [Into::into]
    // struct name, required
    MyStruct
    // generics, optional, must be in brackets `[..]`
    // this is equivalent to specifying `::<f32, String>`
    [f32, String]
    // fields
    {
        // name value pairs like normal structs
        //
        // value is converted via the conversion function
        // name: Into::into(value),
        name: value,
        // use `effect` boxed to do another conversion, see the `effect!` macro.
        boxed: @boxed inner,
        // Nested structs will be recursively applied this macro
        // `OtherStruct` will be constructed using the same `meta_default_constructor!`
        // use another syntax like wrapping it in parenthesis to ignore this
        other: OtherStruct {
            ..
        },
        // append [..Default::default()] at the end
    }
)