Module :: former_types

A flexible and extensible implementation of the builder pattern. Its compile-time structures and traits that are not generated but reused.

Example: Using Trait ComponentAssign

Demonstrates setting various components (fields) of a struct.

The former_types crate provides a generic interface for setting components on an object. This example defines a Person struct and implements the ComponentAssign trait for its fields. It shows how to use these implementations to set the fields of a Person instance using different types that can be converted into the required types.

#[ cfg( any( not( feature = "derive_former" ), not( feature = "enabled" ) ) ) ]
fn main() {}

#[ cfg( all( feature = "derive_former", feature = "enabled" ) ) ]
fn main()
{
  use former_types::ComponentAssign;

  #[ derive( Default, PartialEq, Debug ) ]
  struct Person
  {
    age : i32,
    name : String,
  }

  impl< IntoT > ComponentAssign< i32, IntoT > for Person
  where
    IntoT : Into< i32 >,
  {
    fn assign( &mut self, component : IntoT )
    {
      self.age = component.into();
    }
  }

  impl< IntoT > ComponentAssign< String, IntoT > for Person
  where
    IntoT : Into< String >,
  {
    fn assign( &mut self, component : IntoT )
    {
      self.name = component.into();
    }
  }

  let mut got : Person = Default::default();
  got.assign( 13 );
  got.assign( "John" );
  assert_eq!( got, Person { age : 13, name : "John".to_string() } );
  dbg!( got );
  // > Person {
  // >   age: 13,
  // >   name: "John",
  // > }

}

Try out cargo run --example former_types_trivial. See code.