Remove is_standard

Add more extensive documentation to is_custom
Change documentation of `method_name` to reflect godot#73052

Author: lilizoey

godot-core/src/builtin/callable.rs

@@ -63,9 +63,16 @@ impl Callable {
         self.as_inner().callv(arguments)
     }
 
-    /// Returns the name of the method represented by this callable.
+    /// Returns the name of the method represented by this callable. If the callable is a lambda function,
+    /// returns the function's name.
+    ///
+    /// ## Known Bugs
+    ///
+    /// Getting the name of a lambda errors instead of returning its name, see [godot#73052].
     ///
     /// _Godot equivalent: `get_method`_
+    ///
+    /// [godot#73052]: https://github.com/godotengine/godot/issues/73052
     pub fn method_name(&self) -> Option<StringName> {
         let method_name = self.as_inner().get_method();
         if method_name.is_empty() {
@@ -111,7 +118,13 @@ impl Callable {
     /// Custom callables are mainly created from bind or unbind. In GDScript, lambda functions are also
     /// custom callables.
     ///
+    /// If a callable is not a custom callable, then it is considered a standard callable, this function is
+    /// the opposite of [`Callable.is_standard`].
+    ///
     /// _Godot equivalent: `is_custom`_
+    ///
+    /// [`Callable.is_standard`]: https://docs.godotengine.org/en/stable/classes/class_callable.html#class-callable-method-is-standard
+    #[doc(alias = "is_standard")]
     pub fn is_custom(&self) -> bool {
         self.as_inner().is_custom()
     }
@@ -126,15 +139,6 @@ impl Callable {
         self.as_inner().is_null()
     }
 
-    /// Returns true if this callable is a standard callable. This method is the opposite of [`is_custom`].
-    ///
-    /// Returns `false` if this callable is a lambda function.
-    ///
-    /// _Godot equivalent: `is_standard`_
-    pub fn is_standard(&self) -> bool {
-        self.as_inner().is_standard()
-    }
-
     /// Returns true if the callable's object exists and has a valid method name assigned, or is a custom
     /// callable.
     ///

itest/rust/src/callable_test.rs

@@ -38,10 +38,10 @@ fn callable_validity() {
     let obj = Gd::<CallableTestObj>::new_default();
     assert!(!obj.callable("doesn't_exist").is_valid());
     assert!(!obj.callable("doesn't_exist").is_null());
-    assert!(obj.callable("doesn't_exist").is_standard());
     assert!(!obj.callable("doesn't_exist").is_custom());
     assert!(obj.callable("foo").is_valid());
     assert!(Callable::default().is_null());
+    assert!(!Callable::default().is_custom());
 }
 
 #[itest]