Merge pull request #266 from amousset/result-type-transport

feat(transport): Use an associated type for result type of EmailTrans…

lettre/src/file/mod.rs

@@ -31,7 +31,9 @@ impl FileEmailTransport {
     }
 }
 
-impl<'a, T: Read + 'a> EmailTransport<'a, T, FileResult> for FileEmailTransport {
+impl<'a, T: Read + 'a> EmailTransport<'a, T> for FileEmailTransport {
+    type Result = FileResult;
+
     fn send<U: SendableEmail<'a, T> + 'a>(&mut self, email: &'a U) -> FileResult {
         let mut file = self.path.clone();
         file.push(format!("{}.txt", email.message_id()));

lettre/src/lib.rs

@@ -212,9 +212,12 @@ pub trait SendableEmail<'a, T: Read + 'a> {
 }
 
 /// Transport method for emails
-pub trait EmailTransport<'a, U: Read + 'a, V> {
+pub trait EmailTransport<'a, U: Read + 'a> {
+    /// Result type for the transport
+    type Result;
+
     /// Sends the email
-    fn send<T: SendableEmail<'a, U> + 'a>(&mut self, email: &'a T) -> V;
+    fn send<T: SendableEmail<'a, U> + 'a>(&mut self, email: &'a T) -> Self::Result;
 }
 
 /// Minimal email structure

lettre/src/sendmail/mod.rs

@@ -32,7 +32,9 @@ impl SendmailTransport {
     }
 }
 
-impl<'a, T: Read + 'a> EmailTransport<'a, T, SendmailResult> for SendmailTransport {
+impl<'a, T: Read + 'a> EmailTransport<'a, T> for SendmailTransport {
+    type Result = SendmailResult;
+
     fn send<U: SendableEmail<'a, T> + 'a>(&mut self, email: &'a U) -> SendmailResult {
         let envelope = email.envelope();
 

lettre/src/smtp/mod.rs

@@ -306,7 +306,9 @@ impl<'a> SmtpTransport {
     }
 }
 
-impl<'a, T: Read + 'a> EmailTransport<'a, T, SmtpResult> for SmtpTransport {
+impl<'a, T: Read + 'a> EmailTransport<'a, T> for SmtpTransport {
+    type Result = SmtpResult;
+
     /// Sends an email
     #[cfg_attr(feature = "cargo-clippy", allow(match_same_arms, cyclomatic_complexity))]
     fn send<U: SendableEmail<'a, T> + 'a>(&mut self, email: &'a U) -> SmtpResult {

lettre/src/stub/mod.rs

@@ -27,7 +27,9 @@ impl StubEmailTransport {
 /// SMTP result type
 pub type StubResult = Result<(), ()>;
 
-impl<'a, T: Read + 'a> EmailTransport<'a, T, StubResult> for StubEmailTransport {
+impl<'a, T: Read + 'a> EmailTransport<'a, T> for StubEmailTransport {
+    type Result = StubResult;
+
     fn send<U: SendableEmail<'a, T>>(&mut self, email: &'a U) -> StubResult {
         let envelope = email.envelope();
         info!(