Implement Default for all backend structs

This fixes the clippy warning new_without_default [0].

[0] https://rust-lang.github.io/rust-clippy/master/index.html#new_without_default

5 files changed, 18 insertions, 16 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0d6256c..939ae76 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@ SPDX-License-Identifier: CC0-1.0
 # Unreleased
 - Add the `KDialog` backend (contributed by Stephan Sokolow).
 - Comply with version 3.0 of the REUSE specification.
+- Implement `Default` for all backend structs.
 
 # v0.2.1 (2019-06-30)
 - Fix the input and password dialogs for the `zenity` backend (thanks Silvano
diff --git a/src/backends/dialog.rs b/src/backends/dialog.rs
index 85b0294..8061d98 100644
--- a/src/backends/dialog.rs
+++ b/src/backends/dialog.rs
@@ -19,11 +19,7 @@ pub struct Dialog {
 impl Dialog {
     /// Creates a new `Dialog` instance without configuration.
     pub fn new() -> Dialog {
-        Dialog {
-            backtitle: None,
-            height: "0".to_string(),
-            width: "0".to_string(),
-        }
+        Default::default()
     }
 
     /// Sets the backtitle for the dialog boxes.
@@ -87,6 +83,16 @@ impl AsRef<Dialog> for Dialog {
     }
 }
 
+impl Default for Dialog {
+    fn default() -> Self {
+        Dialog {
+            backtitle: None,
+            height: "0".to_string(),
+            width: "0".to_string(),
+        }
+    }
+}
+
 fn require_success(status: process::ExitStatus) -> Result<()> {
     if status.success() {
         Ok(())
diff --git a/src/backends/kdialog.rs b/src/backends/kdialog.rs
index 34070c4..c2ddcd0 100644
--- a/src/backends/kdialog.rs
+++ b/src/backends/kdialog.rs
@@ -20,7 +20,7 @@ const CANCEL: i32 = 1;
 /// The `kdialog` backend.
 ///
 /// This backend uses the external `kdialog` program to display KDE dialog boxes.
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct KDialog {
     icon: Option<String>,
     // TODO: --dontagain
@@ -29,7 +29,7 @@ pub struct KDialog {
 impl KDialog {
     /// Creates a new `KDialog` instance without configuration.
     pub fn new() -> KDialog {
-        KDialog { icon: None }
+        Default::default()
     }
 
     /// Sets the icon in the dialog box's titlebar and taskbar button.
diff --git a/src/backends/stdio.rs b/src/backends/stdio.rs
index 4e4c8ec..9a153df 100644
--- a/src/backends/stdio.rs
+++ b/src/backends/stdio.rs
@@ -9,13 +9,13 @@ use crate::{Choice, Input, Message, Password, Question, Result};
 ///
 /// This backend is intended as a fallback backend to use if no other backend is available.  The
 /// dialogs are printed to the standard output and user input is read from the standard input.
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct Stdio {}
 
 impl Stdio {
     /// Creates a new `Stdio` instance.
     pub fn new() -> Stdio {
-        Stdio {}
+        Default::default()
     }
 }
 
diff --git a/src/backends/zenity.rs b/src/backends/zenity.rs
index d5745eb..0deca0a 100644
--- a/src/backends/zenity.rs
+++ b/src/backends/zenity.rs
@@ -8,7 +8,7 @@ use crate::{Choice, Error, Input, Message, Password, Question, Result};
 /// The `zenity` backend.
 ///
 /// This backend uses the external `zenity` program to display GTK+ dialog boxes.
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct Zenity {
     icon: Option<String>,
     width: Option<String>,
@@ -19,12 +19,7 @@ pub struct Zenity {
 impl Zenity {
     /// Creates a new `Zenity` instance without configuration.
     pub fn new() -> Zenity {
-        Zenity {
-            icon: None,
-            width: None,
-            height: None,
-            timeout: None,
-        }
+        Default::default()
     }
 
     /// Sets the icon of the dialog box.