Merge pull request #35 from sveltejs/master

Sync Fork from Upstream Repo

Author: sthagen

site/content/docs/01-component-format.md

@@ -147,24 +147,7 @@ If a statement consists entirely of an assignment to an undeclared variable, Sve
 
 ---
 
-A *store* is any object that allows reactive access to a value via a simple *store contract*.
-
-The [`svelte/store` module](docs#svelte_store) contains minimal store implementations which fulfil this contract. You can use these as the basis for your own stores, or you can implement your stores from scratch.
-
-A store must contain a `.subscribe` method, which must accept as its argument a subscription function. This subscription function must be immediately and synchronously called with the store's current value upon calling `.subscribe`. All of a store's active subscription functions must later be synchronously called whenever the store's value changes. The `.subscribe` method must also return an unsubscription function. Calling an unsubscription function must stop its subscription, and its corresponding subscription function must not be called again by the store.
-
-A store may optionally contain a `.set` method, which must accept as its argument a new value for the store, and which synchronously calls all of the store's active subscription functions. Such a store is called a *writable store*.
-
-```js
-const unsubscribe = store.subscribe(value => {
-	console.log(value);
-}); // logs `value`
-
-// later...
-unsubscribe();
-```
-
----
+A *store* is an object that allows reactive access to a value via a simple *store contract*. The [`svelte/store` module](docs#svelte_store) contains minimal store implementations which fulfil this contract.
 
 Any time you have a reference to a store, you can access its value inside a component by prefixing it with the `$` character. This causes Svelte to declare the prefixed variable, and set up a store subscription that will be unsubscribed when appropriate.
 
@@ -189,6 +172,20 @@ Local variables (that do not represent store values) must *not* have a `$` prefi
 </script>
 ```
 
+##### Store contract
+
+```js
+store = { subscribe: (subscription: (value: any) => void) => () => void, set?: (value: any) => void }
+```
+
+You can create your own stores without relying on [`svelte/store`](docs#svelte_store), by implementing the *store contract*:
+
+1. A store must contain a `.subscribe` method, which must accept as its argument a subscription function. This subscription function must be immediately and synchronously called with the store's current value upon calling `.subscribe`. All of a store's active subscription functions must later be synchronously called whenever the store's value changes.
+2. The `.subscribe` method must return an unsubscribe function. Calling an unsubscribe function must stop its subscription, and its corresponding subscription function must not be called again by the store.
+3. A store may *optionally* contain a `.set` method, which must accept as its argument a new value for the store, and which synchronously calls all of the store's active subscription functions. Such a store is called a *writable store*.
+
+For interoperability with RxJS Observables, the `.subscribe` method is also allowed to return an object with an `.unsubscribe` method, rather than return the unsubscription function directly. Note however that unless `.subscribe` synchronously calls the subscription (which is not required by the Observable spec), Svelte will see the value of the store as `undefined` until it does.
+
 
 ### &lt;script context="module"&gt;
 

site/content/docs/02-template-syntax.md

@@ -1018,7 +1018,7 @@ DOMRect {
 	​top: number,
 	width: number,
 	x: number,
-	y:number
+	y: number
 }
 ```
 

site/content/docs/03-run-time.md

@@ -214,7 +214,11 @@ Events dispatched from child components can be listened to in their parent. Any
 
 ### `svelte/store`
 
-The `svelte/store` module exports functions for creating [stores](docs#4_Prefix_stores_with_$_to_access_their_values).
+The `svelte/store` module exports functions for creating [readable](docs#readable), [writable](docs#writable) and [derived](docs#derived) stores.
+
+Keep in mind that you don't *have* to use these functions to enjoy the [reactive `$store` syntax](docs#4_Prefix_stores_with_$_to_access_their_values) in your components. Any object that correctly implements `.subscribe`, unsubscribe, and (optionally) `.set` is a valid store, and will work both with the special syntax, and with Svelte's built-in [`derived` stores](docs#derived).
+
+This makes it possible to wrap almost any other reactive state handling library for use in Svelte. Read more about the [store contract](docs#Store_contract) to see what a correct implementation looks like.
 
 #### `writable`
 

src/compiler/compile/Component.ts

@@ -472,7 +472,7 @@ export default class Component {
 							if (variable.writable && !(variable.referenced || variable.referenced_from_script || variable.subscribable)) {
 								this.warn(declarator, {
 									code: `unused-export-let`,
-									message: `${this.name.name} has unused export property '${name}'. If it is for external reference only, please consider using \`export const '${name}'\``
+									message: `${this.name.name} has unused export property '${name}'. If it is for external reference only, please consider using \`export const ${name}\``
 								});
 							}
 						});
@@ -495,7 +495,7 @@ export default class Component {
 						if (variable.writable && !(variable.referenced || variable.referenced_from_script || variable.subscribable)) {
 							this.warn(specifier, {
 								code: `unused-export-let`,
-								message: `${this.name.name} has unused export property '${specifier.exported.name}'. If it is for external reference only, please consider using \`export const '${specifier.exported.name}'\``
+								message: `${this.name.name} has unused export property '${specifier.exported.name}'. If it is for external reference only, please consider using \`export const ${specifier.exported.name}\``
 							});
 						}
 					}

test/validator/samples/unreferenced-variables/warnings.json

@@ -6,7 +6,7 @@
 			"column": 12,
 			"line": 8
 		},
-		"message": "Component has unused export property 'd'. If it is for external reference only, please consider using `export const 'd'`",
+		"message": "Component has unused export property 'd'. If it is for external reference only, please consider using `export const d`",
 		"pos": 102,
 		"start": {
 			"character": 102,
@@ -21,7 +21,7 @@
 			"column": 15,
 			"line": 8
 		},
-		"message": "Component has unused export property 'e'. If it is for external reference only, please consider using `export const 'e'`",
+		"message": "Component has unused export property 'e'. If it is for external reference only, please consider using `export const e`",
 		"pos": 105,
 		"start": {
 			"character": 105,
@@ -36,7 +36,7 @@
 			"column": 18,
 			"line": 9
 		},
-		"message": "Component has unused export property 'g'. If it is for external reference only, please consider using `export const 'g'`",
+		"message": "Component has unused export property 'g'. If it is for external reference only, please consider using `export const g`",
 		"pos": 125,
 		"start": {
 			"character": 125,
@@ -51,7 +51,7 @@
 			"column": 18,
 			"line": 10
 		},
-		"message": "Component has unused export property 'h'. If it is for external reference only, please consider using `export const 'h'`",
+		"message": "Component has unused export property 'h'. If it is for external reference only, please consider using `export const h`",
 		"pos": 145,
 		"start": {
 			"character": 145,
@@ -66,7 +66,7 @@
 			"column": 25,
 			"line": 12
 		},
-		"message": "Component has unused export property 'j'. If it is for external reference only, please consider using `export const 'j'`",
+		"message": "Component has unused export property 'j'. If it is for external reference only, please consider using `export const j`",
 		"pos": 187,
 		"start": {
 			"character": 187,