Digital v1 <-> v2 compatibility wrappers and shims

CHANGELOG.md

@@ -13,6 +13,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   fallible and their methods now return a `Result` type as setting an output pin
   and reading an input pin could potentially fail.
   See [here](https://github.com/rust-embedded/embedded-hal/issues/95) for more info.
+- Compatibility shims between `digital::v1` and `digital::v2` traits allowing v1 traits
+  to be implicitly promoted to v2, and for v2 traits to be explicitly cast to v1 wrappers.
 
 ### Changed
 - The current versions of the `OutputPin`, `StatefulOutputPin`, `ToggleableOutputPin`

src/digital/mod.rs

@@ -1,155 +1,25 @@
 //! Digital I/O
 //!
-//! The traits in this module are now deprecated. Please use the new versions included
-//! in `digital::v2`.
-
-/// Single digital push-pull output pin
-///
-/// *This version of the trait is now deprecated. Please use the new `OutputPin` trait in
-/// `digital::v2::OutputPin`*.
-#[deprecated(since = "0.2.2", note = "Deprecated because the methods cannot return errors. \
-                                      Users should use the traits in digital::v2.")]
-pub trait OutputPin {
-    /// Drives the pin low
-    ///
-    /// *NOTE* the actual electrical state of the pin may not actually be low, e.g. due to external
-    /// electrical sources
-    fn set_low(&mut self);
-
-    /// Drives the pin high
-    ///
-    /// *NOTE* the actual electrical state of the pin may not actually be high, e.g. due to external
-    /// electrical sources
-    fn set_high(&mut self);
-}
-
-/// Push-pull output pin that can read its output state
-///
-/// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
-///
-/// *This version of the trait is now deprecated. Please use the new `StatefulOutputPin` trait in
-/// `digital::v2::StatefulOutputPin`*.
-#[deprecated(since = "0.2.2", note = "Deprecated because the methods cannot return errors. \
-                                      Users should use the traits in digital::v2.")]
-#[cfg(feature = "unproven")]
-pub trait StatefulOutputPin {
-    /// Is the pin in drive high mode?
-    ///
-    /// *NOTE* this does *not* read the electrical state of the pin
-    fn is_set_high(&self) -> bool;
-
-    /// Is the pin in drive low mode?
-    ///
-    /// *NOTE* this does *not* read the electrical state of the pin
-    fn is_set_low(&self) -> bool;
-}
-
-/// Output pin that can be toggled
-///
-/// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
-///
-/// *This version of the trait is now deprecated. Please use the new `ToggleableOutputPin`
-/// trait in `digital::v2::ToggleableOutputPin`*.
-///
-/// See [toggleable](toggleable) to use a software implementation if
-/// both [OutputPin](trait.OutputPin.html) and
-/// [StatefulOutputPin](trait.StatefulOutputPin.html) are
-/// implemented. Otherwise, implement this using hardware mechanisms.
-#[deprecated(since = "0.2.2", note = "Deprecated because the methods cannot return errors. \
-                                      Users should use the traits in digital::v2.")]
-#[cfg(feature = "unproven")]
-pub trait ToggleableOutputPin {
-    /// Toggle pin output.
-    fn toggle(&mut self);
-}
+//! 
+//!
 
-/// If you can read **and** write the output state, a pin is
-/// toggleable by software.
-///
-/// *This version of the module is now deprecated. Please use the new `toggleable` module in
-/// `digital::v2::toggleable`*.
-///
-/// ```
-/// use embedded_hal::digital::{OutputPin, StatefulOutputPin, ToggleableOutputPin};
-/// use embedded_hal::digital::toggleable;
-///
-/// /// A virtual output pin that exists purely in software
-/// struct MyPin {
-///     state: bool
-/// }
-///
-/// impl OutputPin for MyPin {
-///    fn set_low(&mut self) {
-///        self.state = false;
-///    }
-///    fn set_high(&mut self) {
-///        self.state = true;
-///    }
-/// }
-///
-/// impl StatefulOutputPin for MyPin {
-///    fn is_set_low(&self) -> bool {
-///        !self.state
-///    }
-///    fn is_set_high(&self) -> bool {
-///        self.state
-///    }
-/// }
-///
-/// /// Opt-in to the software implementation.
-/// impl toggleable::Default for MyPin {}
-///
-/// let mut pin = MyPin { state: false };
-/// pin.toggle();
-/// assert!(pin.is_set_high());
-/// pin.toggle();
-/// assert!(pin.is_set_low());
-/// ```
+// Deprecated / infallible traits
 #[deprecated(since = "0.2.2", note = "Deprecated because the methods cannot return errors. \
                                       Users should use the traits in digital::v2.")]
-#[cfg(feature = "unproven")]
-pub mod toggleable {
-    #[allow(deprecated)]
-    use super::{OutputPin, StatefulOutputPin, ToggleableOutputPin};
+pub mod v1;
 
-    /// Software-driven `toggle()` implementation.
-    ///
-    /// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
-    #[allow(deprecated)]
-    pub trait Default: OutputPin + StatefulOutputPin {}
+// New / fallible traits
+pub mod v2;
 
-    #[allow(deprecated)]
-    impl<P> ToggleableOutputPin for P
-    where
-        P: Default,
-    {
-        /// Toggle pin output
-        fn toggle(&mut self) {
-            if self.is_set_low() {
-                self.set_high();
-            } else {
-                self.set_low();
-            }
-        }
-    }
-}
+// v2 -> v1 compatibility wrappers
+// These require explicit casts from v2 -> v1
+pub mod v1_compat;
 
-/// Single digital input pin
-///
-/// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
-///
-/// *This version of the trait is now deprecated. Please use the new `InputPin` trait in
-/// `digital::v2::InputPin`*.
-#[deprecated(since = "0.2.2", note = "Deprecated because the methods cannot return errors. \
-                                      Users should use the traits in digital::v2.")]
-#[cfg(feature = "unproven")]
-pub trait InputPin {
-    /// Is the input pin high?
-    fn is_high(&self) -> bool;
+// v1 -> v2 compatibility shims
+// These are implicit over v1 implementations
+pub mod v2_compat;
 
-    /// Is the input pin low?
-    fn is_low(&self) -> bool;
-}
+// Re-export old traits so this isn't a breaking change
+#[allow(deprecated)]
+pub use self::v1::*;
 
-/// Improved version of the digital traits where the methods can also return an error.
-pub mod v2;

src/digital/v1.rs

@@ -0,0 +1,145 @@
+//! Digital I/O
+//!
+//! The traits in this module are now deprecated. Please use the new versions included
+//! in `digital::v2`.
+
+#![allow(deprecated)]
+
+/// Single digital push-pull output pin
+///
+/// *This version of the trait is now deprecated. Please use the new `OutputPin` trait in
+/// `digital::v2::OutputPin`*.
+
+pub trait OutputPin {
+    /// Drives the pin low
+    ///
+    /// *NOTE* the actual electrical state of the pin may not actually be low, e.g. due to external
+    /// electrical sources
+    fn set_low(&mut self);
+
+    /// Drives the pin high
+    ///
+    /// *NOTE* the actual electrical state of the pin may not actually be high, e.g. due to external
+    /// electrical sources
+    fn set_high(&mut self);
+}
+
+/// Push-pull output pin that can read its output state
+///
+/// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
+///
+/// *This version of the trait is now deprecated. Please use the new `StatefulOutputPin` trait in
+/// `digital::v2::StatefulOutputPin`*.
+#[cfg(feature = "unproven")]
+pub trait StatefulOutputPin {
+    /// Is the pin in drive high mode?
+    ///
+    /// *NOTE* this does *not* read the electrical state of the pin
+    fn is_set_high(&self) -> bool;
+
+    /// Is the pin in drive low mode?
+    ///
+    /// *NOTE* this does *not* read the electrical state of the pin
+    fn is_set_low(&self) -> bool;
+}
+
+/// Output pin that can be toggled
+///
+/// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
+///
+/// *This version of the trait is now deprecated. Please use the new `ToggleableOutputPin`
+/// trait in `digital::v2::ToggleableOutputPin`*.
+///
+/// See [toggleable](toggleable) to use a software implementation if
+/// both [OutputPin](trait.OutputPin.html) and
+/// [StatefulOutputPin](trait.StatefulOutputPin.html) are
+/// implemented. Otherwise, implement this using hardware mechanisms.
+#[cfg(feature = "unproven")]
+pub trait ToggleableOutputPin {
+    /// Toggle pin output.
+    fn toggle(&mut self);
+}
+
+/// If you can read **and** write the output state, a pin is
+/// toggleable by software.
+///
+/// *This version of the module is now deprecated. Please use the new `toggleable` module in
+/// `digital::v2::toggleable`*.
+///
+/// ```
+/// use embedded_hal::digital::{OutputPin, StatefulOutputPin, ToggleableOutputPin};
+/// use embedded_hal::digital::toggleable;
+///
+/// /// A virtual output pin that exists purely in software
+/// struct MyPin {
+///     state: bool
+/// }
+///
+/// impl OutputPin for MyPin {
+///    fn set_low(&mut self) {
+///        self.state = false;
+///    }
+///    fn set_high(&mut self) {
+///        self.state = true;
+///    }
+/// }
+///
+/// impl StatefulOutputPin for MyPin {
+///    fn is_set_low(&self) -> bool {
+///        !self.state
+///    }
+///    fn is_set_high(&self) -> bool {
+///        self.state
+///    }
+/// }
+///
+/// /// Opt-in to the software implementation.
+/// impl toggleable::Default for MyPin {}
+///
+/// let mut pin = MyPin { state: false };
+/// pin.toggle();
+/// assert!(pin.is_set_high());
+/// pin.toggle();
+/// assert!(pin.is_set_low());
+/// ```
+#[cfg(feature = "unproven")]
+pub mod toggleable {
+    #[allow(deprecated)]
+    use super::{OutputPin, StatefulOutputPin, ToggleableOutputPin};
+
+    /// Software-driven `toggle()` implementation.
+    ///
+    /// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
+    #[allow(deprecated)]
+    pub trait Default: OutputPin + StatefulOutputPin {}
+
+    #[allow(deprecated)]
+    impl<P> ToggleableOutputPin for P
+    where
+        P: Default,
+    {
+        /// Toggle pin output
+        fn toggle(&mut self) {
+            if self.is_set_low() {
+                self.set_high();
+            } else {
+                self.set_low();
+            }
+        }
+    }
+}
+
+/// Single digital input pin
+///
+/// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
+///
+/// *This version of the trait is now deprecated. Please use the new `InputPin` trait in
+/// `digital::v2::InputPin`*.
+#[cfg(feature = "unproven")]
+pub trait InputPin {
+    /// Is the input pin high?
+    fn is_high(&self) -> bool;
+
+    /// Is the input pin low?
+    fn is_low(&self) -> bool;
+}