Package List inheritance by abusing deref

Signed-off-by: Luca Fulchir <luca.fulchir@runesauth.com>

bok/src/libt/mod.rs

@@ -31,7 +31,14 @@ macro_rules! moduse {
 }
 pub use moduse;
 
-pub trait PkgList {}
+pub trait PkgsList {}
+
+///
+/// This is an empty Package List. Will be available in the main library
+///
+#[derive(::std::default::Default)]
+pub struct PkgsEmpty {}
+impl PkgsList for PkgsEmpty {}
 
 pub trait Pkg: Any {
     fn as_any(&self) -> &dyn Any

bok/src/main.rs

@@ -20,17 +20,12 @@ mod libt;
 mod pkgs;
 
 fn main() {
-    use pkgs::Pkgs1NewPkgs;
-    use pkgs::Pkgs1Pkgs;
-    let pkgs1 = pkgs::Pkgs1 {};
-    use pkgs::Pkgs2NewPkgs;
-    use pkgs::Pkgs2Pkgs;
-    let pkgs2 = pkgs::Pkgs2 {};
-    use pkgs::*;
+    let pkgs1 = pkgs::Pkgs1::default();
+    let pkgs2 = pkgs::Pkgs2::default();
 
-    println!("{}", Pkgs1::one().my_attr);
-    println!("{}", Pkgs1::two().my_attr);
-    println!("{}", <Pkgs2 as Pkgs1NewPkgs>::one().my_attr);
-    println!("{}", <Pkgs2 as Pkgs2NewPkgs>::two().my_attr);
-    println!("{}", Pkgs2::three().my_attr);
+    println!("pkgs1 - 1:{}", pkgs1.one().my_attr);
+    println!("pkgs1 - 2:{}", pkgs1.two().my_attr);
+    println!("pkgs2 - 1:{}", pkgs2.one().my_attr);
+    println!("pkgs2 - 2:{}", pkgs2.two().my_attr);
+    println!("pkgs2 - 3:{}", pkgs2.three().my_attr);
 }

bok/src/pkgs/mod.rs

@@ -15,53 +15,73 @@
  * limitations under the License.
  */
 
+//!
+//! Example of two package repositories, where one
+//! extends ancd changes another
+//!
+
 use crate::libt;
 //use ::std::{boxed::Box, vec::Vec};
 
 crate::libt::moduse! {
     one
-        two
-        three
+    two
+    three
 }
 
 ///
-/// This is a Package List
+/// This is a base Package List
 ///
-/// eventually all this will be replaced by macros
-pub struct Pkgs1 {}
+#[derive(::std::default::Default)]
+pub struct Pkgs1 {
+    base: libt::PkgsEmpty,
+}
+/// eventually PkgsList and deref will be replaced by macros
+impl libt::PkgsList for Pkgs1 {}
+impl ::std::ops::Deref for Pkgs1 {
+    type Target = libt::PkgsEmpty;
+    fn deref(&self) -> &libt::PkgsEmpty {
+        &self.base
+    }
+}
 
-pub trait Pkgs1NewPkgs {
-    fn one() -> One {
+impl Pkgs1 {
+    /// Packages like this can become a  macro
+    pub fn one(&self) -> One {
         One::new()
     }
-    fn two() -> Two {
+    /// Packages like this can become a  macro
+    pub fn two(&self) -> Two {
         Two::new()
     }
 }
-pub trait Pkgs1Pkgs: Pkgs1NewPkgs + libt::PkgList {}
-
-impl Pkgs1NewPkgs for Pkgs1 {}
-//impl<Pkgs1: Pkgs1NewPkgs + libt::PkgList> Pkgs1Pkgs for Pkgs1 {}
-impl<Pkgs1: Pkgs1NewPkgs + libt::PkgList> Pkgs1Pkgs for Pkgs1 {}
 
 ///
 /// This is a Package List that extends and changes Pkgs1
 ///
-/// eventually all this will be replaced by macros
-pub struct Pkgs2 {}
+#[derive(::std::default::Default)]
+pub struct Pkgs2 {
+    base: Pkgs1,
+}
+/// eventually PkgsList and deref will be replaced by macros
+impl libt::PkgsList for Pkgs2 {}
 
-pub trait Pkgs2NewPkgs {
-    fn two() -> Two {
+impl ::std::ops::Deref for Pkgs2 {
+    type Target = Pkgs1;
+    fn deref(&self) -> &Pkgs1 {
+        &self.base
+    }
+}
+
+impl Pkgs2 {
+    /// example of option override in a package
+    pub fn two(&self) -> Two {
         let mut t = Two::new();
         t.my_attr = 42;
         t
     }
-    fn three() -> Three {
+    /// Packages like this can become a  macro
+    pub fn three(&self) -> Three {
         Three::new()
     }
 }
-
-pub trait Pkgs2Pkgs: Pkgs2NewPkgs + Pkgs1Pkgs {}
-impl<Pkgs2: Pkgs2NewPkgs + Pkgs1Pkgs> Pkgs2Pkgs for Pkgs2 {}
-impl Pkgs2NewPkgs for Pkgs2 {}
-impl Pkgs1NewPkgs for Pkgs2 {}

bok/src/pkgs/three.rs

@@ -25,6 +25,6 @@ impl libt::Pkg for Three {}
 
 impl Three {
     pub fn new() -> Self {
-        Three { my_attr: 42 }
+        Three { my_attr: 3 }
     }
 }