melib: remove BackendOpGenerator

benches/parse.rs

@@ -2,7 +2,6 @@
 //extern crate melib;
 //
 //use melib::mailbox::backends::maildir::MaildirOp;
-//use melib::mailbox::backends::BackendOpGenerator;
 //use melib::mailbox::email::Envelope;
 //
 //extern crate test;

melib/src/backends.rs

@@ -155,7 +155,7 @@ pub trait MailBackend: ::std::fmt::Debug {
 }
 
 /// A `BackendOp` manages common operations for the various mail backends. They only live for the
-/// duration of the operation. They are generated by `BackendOpGenerator` on demand.
+/// duration of the operation. They are generated by the `operation` method of `Mailbackend` trait.
 ///
 /// # Motivation
 ///
@@ -171,7 +171,7 @@ pub trait MailBackend: ::std::fmt::Debug {
 ///
 /// # Example
 /// ```
-/// use melib::mailbox::backends::{BackendOp, BackendOpGenerator};
+/// use melib::mailbox::backends::{BackendOp};
 /// use melib::Result;
 /// use melib::{Envelope, Flag};
 ///
@@ -196,8 +196,7 @@ pub trait MailBackend: ::std::fmt::Debug {
 ///     }
 /// }
 ///
-/// let foogen = BackendOpGenerator::new(Box::new(|| Box::new(FooOp {})));
-/// let operation = foogen.generate();
+/// let operation = Box::new(FooOp {});
 /// assert_eq!("Foobar", &operation.description());
 /// ```
 pub trait BackendOp: ::std::fmt::Debug + ::std::marker::Send {
@@ -211,26 +210,6 @@ pub trait BackendOp: ::std::fmt::Debug + ::std::marker::Send {
     fn set_flag(&mut self, envelope: &mut Envelope, flag: Flag) -> Result<()>;
 }
 
-/// `BackendOpGenerator` is a wrapper for a closure that returns a `BackendOp` object
-/// See `BackendOp` for details.
-/*
- * I know this sucks, but that's the best way I found that rustc deems safe.
- * */
-pub struct BackendOpGenerator(Box<Fn() -> Box<BackendOp>>);
-impl BackendOpGenerator {
-    pub fn new(b: Box<Fn() -> Box<BackendOp>>) -> Self {
-        BackendOpGenerator(b)
-    }
-    pub fn generate(&self) -> Box<BackendOp> {
-        self.0()
-    }
-}
-unsafe impl Send for BackendOpGenerator {}
-unsafe impl Sync for BackendOpGenerator {}
-impl fmt::Debug for BackendOpGenerator {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let op = self.generate();
-        write!(f, "BackendOpGenerator: {}", op.description())
     }
 }