refactor(Defaults): derives traits instead of manual implementation

src/args/arg.rs

@@ -40,6 +40,7 @@ use usageparser::{UsageParser, UsageToken};
 /// Arg::from_usage("-i --input=[input] 'Provides an input file to the program'")
 /// # ).get_matches();
 #[allow(missing_debug_implementations)]
+#[derive(Default)]
 pub struct Arg<'n, 'l, 'h, 'g, 'p, 'r> {
     /// The unique name of the argument
     pub name: &'n str,
@@ -98,34 +99,6 @@ pub struct Arg<'n, 'l, 'h, 'g, 'p, 'r> {
     pub hidden: bool,
 }
 
-impl<'n, 'l, 'h, 'g, 'p, 'r> Default for Arg<'n, 'l, 'h, 'g, 'p, 'r> {
-    fn default() -> Self {
-        Arg {
-            name: "",
-            short: None,
-            long: None,
-            help: None,
-            required: false,
-            takes_value: false,
-            multiple: false,
-            index: None,
-            possible_vals: None,
-            blacklist: None,
-            requires: None,
-            num_vals: None,
-            min_vals: None,
-            max_vals: None,
-            val_names: None,
-            group: None,
-            global: false,
-            empty_vals: true,
-            validator: None,
-            overrides: None,
-            hidden: false,
-        }
-    }
-}
-
 impl<'n, 'l, 'h, 'g, 'p, 'r> Arg<'n, 'l, 'h, 'g, 'p, 'r> {
     /// Creates a new instance of `Arg` using a unique string name.
     /// The name will be used by the library consumer to get information about
@@ -148,6 +121,7 @@ impl<'n, 'l, 'h, 'g, 'p, 'r> Arg<'n, 'l, 'h, 'g, 'p, 'r> {
     pub fn with_name(n: &'n str) -> Self {
         Arg {
             name: n,
+            empty_vals: true,
             ..Default::default()
         }
     }
@@ -379,6 +353,7 @@ impl<'n, 'l, 'h, 'g, 'p, 'r> Arg<'n, 'l, 'h, 'g, 'p, 'r> {
             required: required,
             takes_value: takes_value,
             multiple: multiple,
+            empty_vals: true,
             num_vals: if num_names > 1 {
                 Some(num_names)
             } else {

src/args/arg_builder/flag.rs

@@ -9,7 +9,7 @@ use Arg;
 use args::AnyArg;
 use args::settings::{ArgFlags, ArgSettings};
 
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct FlagBuilder<'n> {
     pub name: &'n str,
     /// The long version of the flag (i.e. word)
@@ -38,13 +38,7 @@ impl<'n> FlagBuilder<'n> {
     pub fn new(name: &'n str) -> Self {
         FlagBuilder {
             name: name,
-            short: None,
-            long: None,
-            help: None,
-            blacklist: None,
-            requires: None,
-            overrides: None,
-            settings: ArgFlags::new(),
+            ..Default::default()
         }
     }
 
@@ -114,10 +108,7 @@ impl<'n, 'a> From<&'a Arg<'n, 'n, 'n, 'n, 'n, 'n>> for FlagBuilder<'n> {
             short: a.short,
             long: a.long,
             help: a.help,
-            blacklist: None,
-            requires: None,
-            overrides: None,
-            settings: ArgFlags::new(),
+            ..Default::default()
         };
         if a.multiple {
             fb.settings.set(&ArgSettings::Multiple);

src/args/arg_builder/option.rs

@@ -10,6 +10,7 @@ use errors::{ClapResult, error_builder};
 use app::App;
 
 #[allow(missing_debug_implementations)]
+#[derive(Default)]
 pub struct OptBuilder<'n> {
     pub name: &'n str,
     /// The short version (i.e. single character) of the argument, no preceding `-`
@@ -36,26 +37,6 @@ pub struct OptBuilder<'n> {
     pub settings: ArgFlags,
 }
 
-impl<'n> Default for OptBuilder<'n> {
-    fn default() -> Self {
-        OptBuilder {
-            name: "",
-            short: None,
-            long: None,
-            help: None,
-            blacklist: None,
-            possible_vals: None,
-            requires: None,
-            num_vals: None,
-            min_vals: None,
-            max_vals: None,
-            val_names: None,
-            validator: None,
-            overrides: None,
-            settings: ArgFlags::new(),
-        }
-    }
-}
 impl<'n> OptBuilder<'n> {
     pub fn new(name: &'n str) -> Self {
         OptBuilder {

src/args/arg_builder/positional.rs

@@ -8,6 +8,7 @@ use args::AnyArg;
 use args::settings::{ArgFlags, ArgSettings};
 
 #[allow(missing_debug_implementations)]
+#[derive(Default)]
 pub struct PosBuilder<'n> {
     pub name: &'n str,
     /// The string of text that will displayed to the user when the application's
@@ -36,16 +37,7 @@ impl<'n> PosBuilder<'n> {
         PosBuilder {
             name: name,
             index: idx,
-            help: None,
-            blacklist: None,
-            possible_vals: None,
-            requires: None,
-            num_vals: None,
-            min_vals: None,
-            max_vals: None,
-            validator: None,
-            overrides: None,
-            settings: ArgFlags::new(),
+            ..Default::default()
         }
     }
 
@@ -75,16 +67,11 @@ impl<'n> PosBuilder<'n> {
         let mut pb = PosBuilder {
             name: a.name,
             index: idx,
-            blacklist: None,
-            requires: None,
-            possible_vals: None,
             num_vals: a.num_vals,
             min_vals: a.min_vals,
             max_vals: a.max_vals,
             help: a.help,
-            validator: None,
-            overrides: None,
-            settings: ArgFlags::new(),
+            ..Default::default()
         };
         if a.multiple {
             pb.settings.set(&ArgSettings::Multiple);

src/args/settings.rs

@@ -50,6 +50,12 @@ impl ArgFlags {
     }
 }
 
+impl Default for ArgFlags {
+    fn default() -> Self {
+        ArgFlags::new()
+    }
+}
+
 #[doc(hidden)]
 #[derive(Debug, PartialEq)]
 pub enum ArgSettings {