From c311de79b1914e984c824535be0c7afe4ff78b7a Mon Sep 17 00:00:00 2001
From: Jeremy Wall <jeremy@marzhillstudios.com>
Date: Thu, 6 Oct 2022 23:59:30 -0400
Subject: [PATCH] Make all the attribute args optional

---
 macros/src/lib.rs             | 17 ++++++++++-------
 wasm-web-component/src/lib.rs | 18 ++++++++++++++----
 2 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/macros/src/lib.rs b/macros/src/lib.rs
index 94dea5c..5419f7c 100644
--- a/macros/src/lib.rs
+++ b/macros/src/lib.rs
@@ -33,7 +33,10 @@ fn expand_crate_ref(name: &str, path: Path) -> syn::Path {
     }
 }
 
-fn get_class_and_element_names(args: Vec<NestedMeta>) -> (Literal, Literal, Literal) {
+fn get_class_and_element_names(
+    args: Vec<NestedMeta>,
+    struct_name: &Ident,
+) -> (Literal, Literal, Literal) {
     let mut class_name = None;
     let mut element_name = None;
     let mut observed_attributes = None;
@@ -54,12 +57,11 @@ fn get_class_and_element_names(args: Vec<NestedMeta>) -> (Literal, Literal, Lite
             }
         }
     }
-    // TODO(jwall): it should be a compile error if this is missing.
-    let class_name = class_name
-        .map(|n| n.token())
-        .unwrap_or_else(|| LitStr::new("", Span::call_site()).token());
 
-    // TODO(jwall): if Missing we should derive this from the class name.
+    let class_name = class_name.map(|n| n.token()).unwrap_or_else(|| {
+        LitStr::new(struct_name.to_string().as_ref(), Span::call_site()).token()
+    });
+
     let element_name = match element_name.map(|n| n.token()) {
         Some(n) => n,
         None => {
@@ -266,7 +268,8 @@ pub fn web_component(attr: TokenStream, item: TokenStream) -> TokenStream {
     let args = parse_macro_input!(attr as AttributeArgs);
     let item_struct = parse_macro_input!(item as ItemStruct);
 
-    let (class_name, element_name, observed_attributes) = get_class_and_element_names(args);
+    let (class_name, element_name, observed_attributes) =
+        get_class_and_element_names(args, &item_struct.ident);
 
     expand_struct(item_struct, class_name, element_name, observed_attributes)
 }
diff --git a/wasm-web-component/src/lib.rs b/wasm-web-component/src/lib.rs
index 80eeccb..e06ba10 100644
--- a/wasm-web-component/src/lib.rs
+++ b/wasm-web-component/src/lib.rs
@@ -11,10 +11,10 @@ use web_sys::{window, Element, HtmlElement};
 /// It expects you to implement the [WebComponentBinding](trait@WebComponentBinding)
 /// trait in order to implement the callbacks.
 ///
-/// It supports three attribute `name = value` parameters.
-/// * `class_name = "ClassName"` - Required. The class name to use for the javascript shim.
-/// * `element_name = "class-name"` - Optional. A valid custom element name to use for the element.
-/// * `observed_attrs = "['attr1', attr2']"` - Optional. A javascript array with a list of observed attributes for this compoment.
+/// It supports three optional attributes `name = value` parameters.
+/// * `class_name = "ClassName"` - The class name to use for the javascript shim. If not provided uses the structs name instead.
+/// * `element_name = "class-name"` - A valid custom element name to use for the element. if not proviced derives it from the class name.
+/// * `observed_attrs = "['attr1', attr2']"` - A javascript array with a list of observed attributes for this compoment. Defaults to "[]".
 ///
 /// Reference [MDN Web Components Guide](https://developer.mozilla.org/en-US/docs/Web/Web_Components)
 pub use wasm_web_component_macros::web_component;
@@ -206,4 +206,14 @@ mod tests {
 
         assert_eq!(AnElement::element_name(), "an-element");
     }
+
+    #[wasm_bindgen_test]
+    fn test_component_no_class_name() {
+        #[web_component]
+        pub struct AnotherElement {}
+        impl WebComponentBinding for AnotherElement {}
+
+        assert_eq!(AnotherElement::class_name(), "AnotherElement");
+        assert_eq!(AnotherElement::element_name(), "another-element");
+    }
 }