Implement TempFileError and traits for it

src/ui/external/editor.rs

@@ -4,6 +4,9 @@ use std::path::PathBuf;
 use std::fs::File;
 use std::error::Error;
 
+use std::fmt::{Debug, Display, Formatter};
+use std::fmt;
+
 use runtime::Runtime;
 
 /*
@@ -49,5 +52,58 @@ impl Drop for TempFile {
 
 
 pub struct TempFileError {
-    cause: Option<Box<Error>>,
+    desc: &'static str,
+    caused_by: Option<Box<Error>>,
 }
+
+impl TempFileError {
+
+    pub fn new(s: &'static str) -> TempFileError {
+        TempFileError {
+            desc: s,
+            caused_by: None,
+        }
+    }
+
+    pub fn with_cause(s: &'static str, c: Box<Error>) -> TempFileError {
+        TempFileError {
+            desc: s,
+            caused_by: Some(c),
+        }
+    }
+
+}
+
+impl Display for TempFileError {
+
+    fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
+        write!(fmt, "TempFileError: '{}'", self.desc);
+        Ok(())
+    }
+}
+
+impl Debug for TempFileError {
+
+    fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
+        write!(fmt, "TempFileError: '{}'", self.desc);
+
+        if let Some(ref e) = self.caused_by {
+            write!(fmt, "  cause: {:?}\n\n", e);
+        }
+
+        Ok(())
+    }
+}
+
+impl Error for TempFileError {
+
+    fn description(&self) -> &str {
+        self.desc
+    }
+
+    fn cause(&self) -> Option<&Error> {
+        self.caused_by.as_ref().map(|e| &**e)
+    }
+
+}
+