Fundamental data types and type constructors, like Single, Pair, Homopair, Many.
In rust, you often need to wrap a given type into a new one. The role of the orphan rules in particular is basically to prevent you from implementing external traits for external types. To overcome the restriction developer usually wrap the external type into a tuple introducing a new type. Type constructor does exactly that and auto-implement traits From, Into, and Deref for the constructed type.
Besides type constructor for single element there are type constructors for pair, homopair and many:
Single to wrap single element.Pair to wrap pair of distinct elements.HomoPair to wrap pair of elements with the same type.Many to wrap Vec of elements.types for type constructingThe same macro types is responsible for generating code for Single, Pair, Homopair, Many. Each type constructor has its own keyword for that, but Pair and Homopair use the same keyword difference in a number of constituent types. It is possible to define all types at once.
```rust use type_constructor::prelude::*;
types! {
single MySingle : f32; single SingleWithParametrized : std::sync::Arc< T : Copy >; single SingleWithParameter : < T >;
pair MyPair : f32; pair PairWithParametrized : std::sync::Arc< T1 : Copy >, std::sync::Arc< T2 : Copy >; pair PairWithParameter : < T1, T2 >;
pair MyHomoPair : f32; pair HomoPairWithParametrized : std::sync::Arc< T : Copy >; pair HomoPairWithParameter : < T >;
many MyMany : f32; many ManyWithParametrized : std::sync::Arc< T : Copy >; many ManyWithParameter : < T >;
} ```
It generates more than 1000 lines of code, which otherwise you would have to write manually.
Macro types is exposed to generate new types, but in some cases, it is enough to reuse already generated types of such kind. The library ships such types: Single, Pair, Homopair, Many. Note: If you avoid generating new types you will get in a position to be not able to define your own implementation of foreign traits because of orphan rule.
rust
let i32_in_tuple = type_constructor::Single::< i32 >::from( 13 );
dbg!( i32_in_tuple );
// i32_in_tuple = Single( 13 )
let i32_and_f32_in_tuple = type_constructor::Pair::< i32, f32 >::from( ( 13, 13.0 ) );
dbg!( i32_and_f32_in_tuple );
// vec_of_i32_in_tuple = Pair( 13, 13.0 )
let two_i32_in_tuple = type_constructor::HomoPair::< i32 >::from( ( 13, 31 ) );
dbg!( two_i32_in_tuple );
// vec_of_i32_in_tuple = HomoPair( 13, 31 )
let vec_of_i32_in_tuple = type_constructor::Many::< i32 >::from( [ 1, 2, 3 ] );
dbg!( vec_of_i32_in_tuple );
// vec_of_i32_in_tuple = Many([ 1, 2, 3 ])
Unlike heteropair homopair has much more traits implemented for it. Among such are: clone_as_tuple, clone_as_array to clone it as either tuple or array, as_tuple, as_array, as_slice to reinterpret it as either tuple or array or slice, traits From/Into are implemented to convert it from/into tuple, array, slice, scalar.
Make is the variadic constructor. It's the unified interface of the arbitrary-length constructor.
After implementing several traits Make0, Make1 up to MakeN one can use make make! to construct instances.
rust ignore
let instance1 : Struct1 = make!();
let instance2 : Struct1 = make!( 13 );
let instance3 : Struct1 = make!( 1, 3 );
To define your own single-use macro types!. The single-line definition looks like that.
rust
use type_constructor::prelude::*;
types!( single MySingle : i32 );
let x = MySingle( 13 );
println!( "x : {}", x.0 );
It generates code:
```rust use type_constructor::prelude::*;
pub struct MySingle( pub i32 );
impl core::ops::Deref for MySingle { type Target = i32; fn deref( &self ) -> &Self::Target { &self.0 } } impl From< i32 > for MySingle { fn from( src : i32 ) -> Self { Self( src ) } } impl From< MySingle > for i32 { fn from( src : MySingle ) -> Self { src.0 } }
let x = MySingle( 13 ); println!( "x : {}", x.0 ); ```
It's possible to define attributes as well as derives.
rust
use type_constructor::prelude::*;
types!
{
/// This is also attribute and macro understands it.
#[ derive( Debug ) ]
single MySingle : i32;
}
let x = MySingle( 13 );
dbg!( x );
It generates code:
```rust use type_constructor::prelude::*;
/// This is also an attribute and macro understands it.
pub struct MySingle( pub i32 );
impl core::ops::Deref for MySingle { type Target = i32; fn deref( &self ) -> &Self::Target { &self.0 } } impl From< i32 > for MySingle { fn from( src : i32 ) -> Self { Self( src ) } } impl From< MySingle > for i32 { fn from( src : MySingle ) -> Self { src.0 } }
let x = MySingle( 13 ); dbg!( x ); ```
Sometimes it's sufficient to use a common type instead of defining a brand new one.
You may use parameterized struct Single< T > instead of macro types! if that is the case.
rust
use type_constructor::prelude::*;
let x = Single::< i32 >( 13 );
dbg!( x );
Element of tuple could be parametrized.
rust
use type_constructor::prelude::*;
types!
{
#[ derive( Debug ) ]
single MySingle : std::sync::Arc< T : Copy >;
}
let x = MySingle( std::sync::Arc::new( 13 ) );
dbg!( x );
It generates code:
```rust use type_constructor::*;
pub struct MySingle< T : Copy >( pub std::sync::Arc< T > );
impl
let x = MySingle( std::sync::Arc::new( 13 ) ); ```
Instead of parametrizing the element, it's possible to define a parametrized tuple.
rust
use type_constructor::prelude::*;
types!
{
#[ derive( Debug ) ]
single MySingle : < T : Copy >;
}
let x = MySingle( 13 );
dbg!( x );
It gererates code:
```rust
pub struct MySingle< T : Copy >( pub T );
impl< T : Copy > core::ops::Deref for MySingle< T > { type Target = T; fn deref( &self ) -> &Self::Target { &self.0 } }
impl< T : Copy > From< T > for MySingle< T > { fn from( src : T ) -> Self { Self( src ) } }
let x = MySingle( 13 ); dbg!( 13 ); ```
Sometimes you need to wrap more than a single element into a tupŠ“e. If types of elements are different use pair. The same macro types is responsible for generating code for both single, pair and also many.
```rust use type_constructor::prelude::*;
types!( pair MyPair : i32, i64 ); let x = MyPair( 13, 31 ); println!( "x : ( {}, {} )", x.0, x.1 ); // prints : x : ( 13, 31 ) ```
It generates code:
rust
Just like single pair may have parameters.
```rust use type_constructor::prelude::*;
use core::fmt; types! { #[ derive( Debug ) ] pair MyPair : < T1 : fmt::Debug, T2 : fmt::Debug >; } let x = MyPair( 13, 13.0 ); dbg!( x ); // prints : x = MyPair( 13, 13.0 ) ```
It generates code:
rust
If you need to wrap pair of elements with the same type use the type constructor pair. The same type constructor pair for both pair and homopair, difference in number of types in definition, homopair has only one, because both its element has the same type. The same macro types is responsible for generating code for both single, pair and also many.
```rust use type_constructor::prelude::*;
types!( pair MyPair : i32, i64 ); let x = MyPair( 13, 31 ); println!( "x : ( {}, {} )", x.0, x.1 ); // prints : x : ( 13, 31 ) ```
It gererates code:
rust
Unlike heteropair homopair has much more traits implemented for it. Among such are: clone_as_tuple, clone_as_array to clone it as either tuple or array, as_tuple, as_array, as_slice to reinterpret it as either tuple or array or slice, traits From/Into are implemented to convert it from/into tuple, array, slice, scalar.
```rust use type_constructor::prelude::*;
use core::fmt; types! { #[ derive( Debug ) ] pair MyHomoPair : < T : fmt::Debug >; } let x = MyHomoPair( 13, 31 ); dbg!( &x ); // prints : &x = MyHomoPair( 13, 31 ) let cloneasarray : [ i32 ; 2 ] = x.cloneasarray(); dbg!( &cloneasarray ); // prints : &cloneasarray = [ 13, 31 ] let cloneastuple : ( i32 , i32 ) = x.cloneastuple(); dbg!( &cloneastuple ); // prints : &cloneastuple = ( 13, 31 ) ```
It gererates code:
rust
Use type constructor many to wrap Vec in a tuple. Similar to single it has essential traits implemented for it.
```rust use type_constructor::prelude::*;
types!( many MyMany : i32 ); let x = MyMany::from( [ 1, 2, 3 ] ); println!( "x : {:?}", x.0 ); ```
It generates code:
rust
Implement traits [Make0], [Make1] up to MakeN to provide the interface to construct your structure with a different set of arguments. In this example structure, Struct1 could be constructed either without arguments, with a single argument, or with two arguments. - Constructor without arguments fills fields with zero. - Constructor with a single argument sets both fields to the value of the argument. - Constructor with 2 arguments set individual values of each field.
```rust use type_constructor::prelude::*;
struct Struct1 { a : i32, b : i32, }
impl Make0 for Struct1 { fn make_0() -> Self { Self { a : 0, b : 0 } } }
impl Make1< i32 > for Struct1 { fn make_1( val : i32 ) -> Self { Self { a : val, b : val } } }
impl Make2< i32, i32 > for Struct1 { fn make_2( val1 : i32, val2 : i32 ) -> Self { Self { a : val1, b : val2 } } }
let got : Struct1 = make!(); let exp = Struct1{ a : 0, b : 0 }; assert_eq!( got, exp );
let got : Struct1 = make!( 13 ); let exp = Struct1{ a : 13, b : 13 }; assert_eq!( got, exp );
let got : Struct1 = make!( 1, 3 ); let exp = Struct1{ a : 1, b : 3 }; assert_eq!( got, exp ); ```
shell
cargo add type_constructor
shell test
git clone https://github.com/Wandalen/wTools
cd wTools
cd sample/rust/type_constructor_trivial_sample
cargo run