feat(export): add Default trait bound for Handler trait

README.md

@@ -79,7 +79,7 @@ use std::convert::From;
 use std::io::{Error as IOError, Write};
 use std::string::FromUtf8Error;
 
-use orgize::export::{html::Escape, DefaultHtmlHandler, HtmlHandler};
+use orgize::export::{DefaultHtmlHandler, HtmlHandler};
 use orgize::{Element, Org};
 use slugify::slugify;
 
@@ -103,6 +103,7 @@ impl From<FromUtf8Error> for MyError {
     }
 }
 
+#[derive(Default)]
 struct MyHtmlHandler(DefaultHtmlHandler);
 
 impl HtmlHandler<MyError> for MyHtmlHandler {
@@ -115,7 +116,7 @@ impl HtmlHandler<MyError> for MyHtmlHandler {
                     w,
                     "<h{0}><a id=\"{1}\" href=\"#{1}\">",
                     title.level,
-                    slugify!(title.raw),
+                    slugify!(&title.raw),
                 )?;
             }
         } else {
@@ -137,8 +138,7 @@ impl HtmlHandler<MyError> for MyHtmlHandler {
 
 fn main() -> Result<(), MyError> {
     let mut writer = Vec::new();
-
+    let mut handler = MyHtmlHandler::default();
-    let mut handler = MyHtmlHandler(DefaultHtmlHandler);
     Org::parse("* title\n*section*").html_with_handler(&mut writer, &mut handler)?;
 
     assert_eq!(

orgize/examples/custom.rs

@@ -29,6 +29,7 @@ impl From<FromUtf8Error> for MyError {
     }
 }
 
+#[derive(Default)]
 struct MyHtmlHandler(DefaultHtmlHandler);
 
 impl HtmlHandler<MyError> for MyHtmlHandler {
@@ -70,7 +71,7 @@ fn main() -> Result<(), MyError> {
         let contents = String::from_utf8(fs::read(&args[1])?)?;
 
         let mut writer = Vec::new();
-        let mut handler = MyHtmlHandler(DefaultHtmlHandler);
+        let mut handler = MyHtmlHandler::default();
         Org::parse(&contents).html_with_handler(&mut writer, &mut handler)?;
 
         println!("{}", String::from_utf8(writer)?);

orgize/src/export/html.rs

@@ -36,7 +36,7 @@ impl<S: AsRef<str>> fmt::Display for Escape<S> {
     }
 }
 
-pub trait HtmlHandler<E: From<Error>> {
+pub trait HtmlHandler<E: From<Error>>: Default {
     fn start<W: Write>(&mut self, mut w: W, element: &Element) -> Result<(), E> {
         use Element::*;
 
@@ -199,6 +199,7 @@ pub trait HtmlHandler<E: From<Error>> {
     }
 }
 
+#[derive(Default)]
 pub struct DefaultHtmlHandler;
 
 impl HtmlHandler<Error> for DefaultHtmlHandler {}

orgize/src/export/org.rs

@@ -3,7 +3,7 @@ use std::io::{Error, Write};
 use crate::elements::{Element, Timestamp};
 use crate::export::write_datetime;
 
-pub trait OrgHandler<E: From<Error>> {
+pub trait OrgHandler<E: From<Error>>: Default {
     fn start<W: Write>(&mut self, mut w: W, element: &Element) -> Result<(), E> {
         use Element::*;
 
@@ -233,6 +233,7 @@ fn write_timestamp<W: Write>(mut w: W, timestamp: &Timestamp) -> std::io::Result
     Ok(())
 }
 
+#[derive(Default)]
 pub struct DefaultOrgHandler;
 
 impl OrgHandler<Error> for DefaultOrgHandler {}

orgize/src/lib.rs

@@ -114,6 +114,7 @@
 //!     }
 //! }
 //!
+//! #[derive(Default)]
 //! struct MyHtmlHandler(DefaultHtmlHandler);
 //!
 //! impl HtmlHandler<MyError> for MyHtmlHandler {
@@ -148,7 +149,7 @@
 //!
 //! fn main() -> Result<(), MyError> {
 //!     let mut writer = Vec::new();
-//!     let mut handler = MyHtmlHandler(DefaultHtmlHandler);
+//!     let mut handler = MyHtmlHandler::default();
 //!     Org::parse("* title\n*section*").html_with_handler(&mut writer, &mut handler)?;
 //!
 //!     assert_eq!(