api(Arg): adds Arg::hide_env_values(bool) which allows one to hide any current env values and display only the key in help messages

Author: kbknapp

src/app/help.rs

@@ -505,11 +505,17 @@ impl<'a> Help<'a> {
                 env.0,
                 env.1
             );
-            spec_vals.push(format!(
-                " [env: {}={}]",
+            let env_val = if !a.is_set(ArgSettings::HideEnvValues) {
+                format!("={}", env.1.map_or(Cow::Borrowed(""), |val| val.to_string_lossy()))
+            } else {
+                String::new()
+            };
+            let env_info = format!(
+                " [env: {}{}]",
                 env.0.to_string_lossy(),
-                env.1.map_or(Cow::Borrowed(""), |val| val.to_string_lossy())
-            ));
+                env_val
+            );
+            spec_vals.push(env_info);
         }
         if !a.is_set(ArgSettings::HideDefaultValue) {
             if let Some(pv) = a.default_val() {

src/args/arg.rs

@@ -3515,6 +3515,15 @@ impl<'a, 'b> Arg<'a, 'b> {
         self
     }
 
+    /// @TODO @p2 @docs @release: write docs
+    pub fn hide_env_values(self, hide: bool) -> Self { 
+        if hide {
+            self.set(ArgSettings::HideEnvValues)
+        } else {
+            self.unset(ArgSettings::HideEnvValues)
+        }
+    }
+
     /// When set to `true` the help string will be displayed on the line after the argument and
     /// indented once. This can be helpful for arguments with very long or complex help messages.
     /// This can also be helpful for arguments with very long flag names, or many/long value names.

src/args/settings.rs

@@ -22,6 +22,7 @@ bitflags! {
         const LAST             = 1 << 14;
         const HIDE_DEFAULT_VAL = 1 << 15;
         const CASE_INSENSITIVE = 1 << 16;
+        const HIDE_ENV_VALS    = 1 << 17;
     }
 }
 
@@ -49,6 +50,7 @@ impl ArgFlags {
         RequireEquals => Flags::REQUIRE_EQUALS,
         Last => Flags::LAST,
         CaseInsensitive => Flags::CASE_INSENSITIVE,
+        HideEnvValues => Flags::HIDE_ENV_VALS,
         HideDefaultValue => Flags::HIDE_DEFAULT_VAL
     }
 }
@@ -96,6 +98,8 @@ pub enum ArgSettings {
     HideDefaultValue,
     /// Makes `Arg::possible_values` case insensitive
     CaseInsensitive,
+    /// Hides ENV values in the help message
+    HideEnvValues,
     #[doc(hidden)] RequiredUnlessAll,
     #[doc(hidden)] ValueDelimiterNotSet,
 }
@@ -121,6 +125,7 @@ impl FromStr for ArgSettings {
             "last" => Ok(ArgSettings::Last),
             "hidedefaultvalue" => Ok(ArgSettings::HideDefaultValue),
             "caseinsensitive" => Ok(ArgSettings::CaseInsensitive),
+            "hideenvvalues" => Ok(ArgSettings::HideEnvValues),
             _ => Err("unknown ArgSetting, cannot convert from str".to_owned()),
         }
     }
@@ -197,6 +202,10 @@ mod test {
             "caseinsensitive".parse::<ArgSettings>().unwrap(),
             ArgSettings::CaseInsensitive
         );
+        assert_eq!(
+            "hideenvvalues".parse::<ArgSettings>().unwrap(),
+            ArgSettings::HideEnvValues
+        );
         assert!("hahahaha".parse::<ArgSettings>().is_err());
     }
 }