fixup! WIP: posts: add mutiple-dispatch-in-c++

content/posts/2022-06-07-multiple-dispatch-in-c++/index.md

@@ -96,22 +96,22 @@ For example, a dummy file-system interface might look like the following:
 ```cpp
 struct Filesystem {
     virtual void write(std::string_view filename, std::span<char> data) = 0;
-    virtual std::vector read(std::string_view filename) = 0;
+    virtual std::vector<char> read(std::string_view filename) = 0;
     virtual void delete(std::string_view filename) = 0;
 };
 ```
 
 You can then write `PosixFilesystem` which makes use of the POSIX API and
 interact with actual on-disk data, `MockFilesystem` which only works in-memory
-and can be used for tests only, etc...
+and can be used for testing, etc...
 
-## Double dispatch
+## Double dispatch through the Visitor pattern
 
-Sometimes single dispatch is not enough, such as in the collision example at
-the beginning of this article. In cases where a computation depends on the
-dynamic type of *two* of its values, we can make use of double-dispatch by
-calling a virtual method on the first value, which will call a virtual method
-on the second value.
+Sometimes single dispatch is not enough, such as in the collision example at the
+beginning of this article. In cases where a computation depends on the dynamic
+type of *two* of its values, we can make use of double-dispatch by leveraging
+the Visitor design pattern. This is done by calling a virtual method on the
+first value, which itself will call a virtual method on the second value.
 
 Here's a commentated example:
 
@@ -161,8 +161,8 @@ void collide(SpaceObject& first, SpaceObject& second) {
 };
 
 int main() {
-    std::unique_ptr<SpaceObject> asteroid = std::make_unique<Asteroid>();
-    std::unique_ptr<SpaceObject> spaceship = std::make_unique<Spaceship>();
+    auto asteroid = std::make_unique<Asteroid>();
+    auto spaceship = std::make_unique<Spaceship>();
 
     collide(*asteroid, *spaceship);
     // Calls in order: