Improve edit api

Author: czocher

rusqlite_migration/src/builder.rs

@@ -1,4 +1,4 @@
-use std::iter::FromIterator;
+use std::{iter::FromIterator, mem::take};
 
 use include_dir::Dir;
 
@@ -42,14 +42,12 @@ impl<'u> MigrationsBuilder<'u> {
     ///
     /// Panics if no migration with the `id` provided exists.
     #[must_use]
-    pub fn edit(mut self, id: usize, f: impl Fn(&mut M)) -> Self {
+    pub fn edit(mut self, id: usize, f: impl Fn(M) -> M) -> Self {
         if id < 1 {
             panic!("id cannot be equal to 0");
         }
-        f(self
-            .migrations
-            .get_mut(id - 1)
-            .expect("No migration with the given index"));
+        let m = take(&mut self.migrations[id - 1]);
+        self.migrations[id - 1] = f(m);
         self
     }
 
@@ -76,8 +74,9 @@ impl<'u> M<'u> {
     /// Use [`M::up_with_hook`] instead if you're creating a new migration.
     /// This method is meant for editing existing transactions
     /// when using the [`MigrationsBuilder`].
-    pub fn set_up_hook(&mut self, hook: impl MigrationHook + 'static) {
+    pub fn set_up_hook(mut self, hook: impl MigrationHook + 'static) -> Self {
         self.up_hook = Some(hook.clone_box());
+        self
     }
 
     /// Replace the `down_hook` in the given migration with the provided one.
@@ -87,7 +86,8 @@ impl<'u> M<'u> {
     /// Use [`M::down_with_hook`] instead if you're creating a new migration.
     /// This method is meant for editing existing transactions
     /// when using the [`MigrationsBuilder`].
-    pub fn set_down_hook(&mut self, hook: impl MigrationHook + 'static) {
+    pub fn set_down_hook(mut self, hook: impl MigrationHook + 'static) -> Self {
         self.down_hook = Some(hook.clone_box());
+        self
     }
 }

rusqlite_migration/src/lib.rs

@@ -171,7 +171,7 @@ impl Clone for Box<dyn MigrationHook> {
 /// A migration can contain up- and down-hooks, which are incomparable closures.
 /// To signify `M` equality we compare if two migrations either don't have hooks defined (they are set to `None`)
 /// or if the closure memory addresses are the same.
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Default)]
 #[must_use]
 pub struct M<'u> {
     up: &'u str,

rusqlite_migration/src/tests/builder.rs

@@ -7,13 +7,13 @@ use crate::{MigrationsBuilder, M};
 fn test_non_existing_index() {
     let ms = vec![M::up("CREATE TABLE t(a);")];
 
-    let _ = MigrationsBuilder::from_iter(ms.clone()).edit(100, move |_t| {});
+    let _ = MigrationsBuilder::from_iter(ms.clone()).edit(100, move |t| t);
 }
 
 #[test]
 #[should_panic]
 fn test_0_index() {
     let ms = vec![M::up("CREATE TABLE t(a);")];
 
-    let _ = MigrationsBuilder::from_iter(ms).edit(0, move |_t| {});
+    let _ = MigrationsBuilder::from_iter(ms).edit(0, move |t| t);
 }