Change: use custom result type, for brevity

1 files changed, 6 insertions, 15 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 32c880a..2ab1ecb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -33,7 +33,6 @@ use serde_yaml;
 use serde_yaml::Value;
 use std::collections::HashMap;
 use textwrap::fill;
-use std::fmt;
 use std::error::Error;
 
 /// A step in a roadmap.
@@ -92,22 +91,14 @@ impl Step {
     }
 }
 
+/// Result type for roadmap parsing.
+type ParseResult<T> = Result<T, String>;
+
 /// All the steps to get to the end goal.
 pub struct Roadmap {
     steps: Vec<Step>,
 }
 
-#[derive(Debug)]
-struct ParseError(String);
-
-impl fmt::Display for ParseError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "ERROR: {}", self.0)
-    }
-}
-
-impl Error for ParseError {}
-
 impl Roadmap {
     /// Create a new, empty roadmap.
     pub fn new() -> Roadmap {
@@ -185,7 +176,7 @@ impl Roadmap {
     }
 
     // Validate that the parsed, constructed roadmap is valid.
-    fn validate(&self) -> Result<(), Box<dyn std::error::Error>> {
+    fn validate(&self) -> ParseResult<()> {
         // Does every step has an acceptable status?
         for step in self.steps.iter() {
             let status = step.status();
@@ -194,7 +185,7 @@ impl Roadmap {
                 _ => {
                     let msg = format!("step {:?} status {:?} is not allowed",
                                       step.name(), status);
-                    return Result::Err(Box::new(ParseError(msg.into())));
+                    return Err(msg);
                 }
             }
         }
@@ -206,7 +197,7 @@ impl Roadmap {
                     None => {
                         let msg = format!("step {} depends on missing {}",
                                           step.name(), depname);
-                        return Result::Err(Box::new(ParseError(msg.into())));
+                        return Err(msg);
                     }
                     Some(_) => (),
                 }