Improve .attribute() parse type ergonomics

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "sysfuss"
-version = "0.3.0"
+version = "0.4.0"
 edition = "2021"
 authors = ["NGnius (Graham) <ngniusness@gmail.com>"]
 description = "sysfs wrapper for convenience"

src/attribute.rs

@@ -35,7 +35,7 @@ pub trait SysAttributeExt: SysAttribute {
     }
     
     /// read and parse the attribute value
-    fn parse<T: FromStr<Err=E>, E, ENT: crate::SysEntity + ?Sized>(&self, entity: &ENT) -> Result<T, EitherErr2<std::io::Error, E>> {
+    fn parse<T: FromStr, ENT: crate::SysEntity + ?Sized>(&self, entity: &ENT) -> Result<T, EitherErr2<std::io::Error, <T as FromStr>::Err>> {
         let s = self.read_str(entity).map_err(EitherErr2::First)?;
         T::from_str(s.trim_end_matches('\n')).map_err(EitherErr2::Second)
     }

src/basic.rs

@@ -5,6 +5,7 @@ use std::io::Result as IoResult;
 const SYS_CLASS_PATH: &str = "sys/class";
 
 /// Generic entity path with basic functionality
+#[derive(PartialEq, Eq)]
 #[cfg_attr(feature = "derive", derive(Debug, Clone))]
 pub struct BasicEntityPath {
     path: PathBuf
@@ -73,6 +74,12 @@ impl crate::SysEntityAttributes<String> for BasicEntityPath {
     }
 }
 
+impl <'a> crate::SysEntityAttributes<&'a str> for BasicEntityPath {
+    fn capabilities(&self) -> Vec<&'a str> {
+        panic!("Cannot read capabilities into &str")
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -104,7 +111,7 @@ mod tests {
             "temp1_alarm".to_string(),
             "temp1_crit".to_string(),
         ].into_iter()))?.next().expect("Missing any hwmon");
-        let attr_value = crate::SysEntityAttributesExt::attribute::<String, _>(&basic, "name".to_owned()).expect("name capable but also incapable");
+        let attr_value = crate::SysEntityAttributesExt::attribute::<String>(&basic, "name".to_owned()).expect("name capable but also incapable");
         println!("Attribute ./name = '{}'", attr_value);
         assert!(attr_value == "nvme");
         Ok(())
@@ -125,7 +132,7 @@ mod tests {
             "dev".to_string(),
             "uevent".to_string(),
         ].into_iter()))?.filter(|basic| basic.name().expect("no name").starts_with("card")).next().expect("Missing drm");
-        let attr_value = crate::SysEntityAttributesExt::attribute::<String, _>(&basic, "dev".to_owned()).expect("dev capable but also incapable");
+        let attr_value = crate::SysEntityAttributesExt::attribute::<String>(&basic, "dev".to_owned()).expect("dev capable but also incapable");
         println!("Attribute ./dev = '{}'", attr_value);
         assert!(attr_value == expected_dev);
         Ok(())

src/entity.rs

@@ -38,7 +38,7 @@ pub trait SysEntity: AsRef<Path> {
 /// sysfs class entity functionality extension
 pub trait SysEntityRawExt: SysEntity {
     /// Get an attribute on the entity
-    fn attribute<A: crate::SysAttribute, T: std::str::FromStr<Err=E>, E>(&self, attr: A) -> Result<T, EitherErr2<std::io::Error, E>>;
+    fn attribute<A: crate::SysAttribute, T: std::str::FromStr>(&self, attr: A) -> Result<T, EitherErr2<std::io::Error, <T as std::str::FromStr>::Err>>;
     /// Get an attribute by filename in the entity's directory
     fn attribute_str<A: AsRef<Path>>(&self, attr: A) -> IoResult<String>;
     
@@ -50,7 +50,7 @@ pub trait SysEntityRawExt: SysEntity {
 }
 
 impl <X: SysEntity> SysEntityRawExt for X {
-    fn attribute<A: crate::SysAttribute, T: std::str::FromStr<Err=E>, E>(&self, attr: A) -> Result<T, EitherErr2<std::io::Error, E>> {
+    fn attribute<A: crate::SysAttribute, T: std::str::FromStr>(&self, attr: A) -> Result<T, EitherErr2<std::io::Error, <T as std::str::FromStr>::Err>> {
         attr.parse(self)
     }
     
@@ -82,7 +82,7 @@ pub trait SysEntityAttributesExt<A: crate::SysAttribute>: SysEntityAttributes<A>
     }
 
     /// Get an attribute on the entity
-    fn attribute<T: std::str::FromStr<Err=E>, E>(&self, attr: A) -> Result<T, EitherErr2<std::io::Error, E>> {
+    fn attribute<T: std::str::FromStr>(&self, attr: A) -> Result<T, EitherErr2<std::io::Error, <T as std::str::FromStr>::Err>> {
         attr.parse(self)
     }
 

src/hwmon.rs

@@ -61,6 +61,8 @@ pub enum HwMonAttributeType {
     Fan,
     /// Current
     Curr,
+    /// Frequency
+    Freq,
 }
 
 impl HwMonAttributeType {
@@ -70,6 +72,7 @@ impl HwMonAttributeType {
             Self::Temp => "out",
             Self::Fan => "fan",
             Self::Curr => "curr",
+            Self::Freq => "freq",
         }
     }
     
@@ -204,7 +207,7 @@ impl HwMonPath {
     pub(crate) fn name(root: &crate::SysPath, name: &str) -> IoResult<Option<Self>> {
         for entry in Self::all(root)? {
             let entry = entry?;
-            let value: String = entry.attribute::<String, _>(HwMonAttribute::name()).map_err(|e| match e {
+            let value: String = entry.attribute::<String>(HwMonAttribute::name()).map_err(|e| match e {
                 crate::EitherErr2::First(e) => e,
                 crate::EitherErr2::Second(_e) => panic!("Infallible"),
             })?;
@@ -269,8 +272,8 @@ mod tests {
         assert!(!all_hwmon.is_empty());
         for hwmon in all_hwmon.into_iter() {
             let hwmon = hwmon?;
-            assert!(hwmon.attribute::<String, _>(HwMonAttribute::name()).map_err(|e| e.map_infallible_second())? != "");
+            assert!(hwmon.attribute::<String>(HwMonAttribute::name()).map_err(|e| e.map_infallible_second())? != "");
-            assert!(!hwmon.attribute::<String, _>(HwMonAttribute::name()).map_err(|e| e.map_infallible_second())?.ends_with("\n"));
+            assert!(!hwmon.attribute::<String>(HwMonAttribute::name()).map_err(|e| e.map_infallible_second())?.ends_with("\n"));
             assert!(!hwmon.capabilities().is_empty());
             assert!(hwmon.capabilities().contains(&HwMonAttribute::name()))
         }
@@ -287,11 +290,10 @@ mod tests {
         }
         let hwmon = sys.hwmon(crate::capability::attributes([
             HwMonAttribute::name(),
-            HwMonAttribute::new(HwMonAttributeType::Fan, 1, HwMonAttributeItem::Input),
+            HwMonAttribute::new(HwMonAttributeType::In, 0, HwMonAttributeItem::Input),
-            HwMonAttribute::new(HwMonAttributeType::Fan, 1, HwMonAttributeItem::Min),
+            HwMonAttribute::new(HwMonAttributeType::In, 0, HwMonAttributeItem::Label),
-            HwMonAttribute::new(HwMonAttributeType::Fan, 1, HwMonAttributeItem::Max)
         ].into_iter()))?.next().expect("Missing capable amdgpu");
-        assert_eq!(hwmon.attribute::<String, _>(HwMonAttribute::name()).expect("name capable but also incapable"), "amdgpu");
+        assert_eq!(hwmon.attribute::<String>(HwMonAttribute::name()).expect("name capable but also incapable"), "amdgpu");
         Ok(())
     }
 }

src/power_supply.rs

@@ -197,6 +197,7 @@ impl std::str::FromStr for PowerSupplyType {
 }
 
 /// power_supply/<entity>/ directory
+#[derive(PartialEq, Eq)]
 #[cfg_attr(feature = "derive", derive(Debug, Clone))]
 pub struct PowerSupplyPath {
     inner: crate::BasicEntityPath,
@@ -293,7 +294,7 @@ mod tests {
     use super::*;
     use crate::SysEntityAttributes;
     use crate::SysEntityAttributesExt;
-    use crate::SysAttribute;
+    use crate::SysAttributeExt;
     
     #[test]
     fn power_supply_all() -> std::io::Result<()> {
@@ -325,7 +326,7 @@ mod tests {
             PowerSupplyAttribute::Type,
             PowerSupplyAttribute::Capacity,
         ].into_iter()))?.next().expect("Missing capable battery");
-        assert!(psu.attribute::<PowerSupplyType, _>(PowerSupplyAttribute::Type).expect("type capable but also incapable") == PowerSupplyType::Battery);
+        assert!(psu.attribute::<PowerSupplyType>(PowerSupplyAttribute::Type).expect("type capable but also incapable") == PowerSupplyType::Battery);
         Ok(())
     }
 }