Closes #63

1. Use `find` instead of `operator []` in `getProxy`.
2. Add `getTypedProxy`.
3. Error if `getProxy` returns a `nullptr`.
4. Add virtual destructor to `Proxy` class.

libmexclass/cpp/source/include/libmexclass/proxy/Proxy.h

@@ -28,6 +28,9 @@ namespace libmexclass::proxy {
 	class Proxy {
 		public:
             Proxy() : methods{} { }
+
+            virtual ~Proxy() {}
+
 			std::optional<libmexclass::error::Error> invoke(libmexclass::proxy::method::Method& method);
         protected:
             std::unordered_map<libmexclass::proxy::method::Name, libmexclass::proxy::method::Object> methods;

libmexclass/cpp/source/include/libmexclass/proxy/ProxyManager.h

@@ -2,11 +2,17 @@
 
 #include "libmexclass/proxy/ID.h"
 #include "libmexclass/proxy/Proxy.h"
+#include "libmexclass/error/Error.h"
 
 #include <memory>
 #include <unordered_map>
+#include <variant>
 
 namespace libmexclass::proxy {
+
+template <typename T>
+using ProxyResult = std::variant<std::shared_ptr<T>, libmexclass::error::Error>;
+
 // ProxyMangager
 // Manages Proxy instances by placing them inside of a map which maps unique IDs
 // to Proxy instances. NOTE: ProxyManager uses the "Singleton" design pattern to
@@ -17,6 +23,23 @@ class ProxyManager {
     static void unmanageProxy(ID id);
     static std::shared_ptr<Proxy> getProxy(ID id);
 
+    template <typename T>
+    static ProxyResult<T> getTypedProxy(ID id) {
+        auto proxy = libmexclass::proxy::ProxyManager::getProxy(id);
+        if (!proxy) {
+            std::string msg = "Invalid Proxy ID: " + std::to_string(id);
+            return libmexclass::error::Error{"libmexclass:proxy:InvalidID", msg};
+        }
+
+        auto typed_proxy = std::dynamic_pointer_cast<T>(proxy);
+        if (!typed_proxy) {
+            std::string msg = "Failed to cast proxy to expected type";
+            return libmexclass::error::Error{"libmexclass:proxy:InvalidProxyType", msg};
+        }
+
+        return typed_proxy;
+    }
+
   private:
     static ProxyManager singleton;
     // The internal map used to associate Proxy instances with unique IDs.
@@ -31,4 +54,5 @@ class ProxyManager {
     //    increment it.
     ID current_proxy_id = 0;
 };
+
 } // namespace libmexclass::proxy

libmexclass/cpp/source/libmexclass/action/MethodCall.cpp

@@ -11,8 +11,11 @@ std::optional<libmexclass::error::Error> MethodCall::execute() {
     // TODO: Implement ID retrieval logic from MethodCall properties.
     // Retrieve the appropriate polymorphic proxy::Proxy instance from the
     // proxy::ProxyManager using the given proxy::ID.
-    std::shared_ptr<libmexclass::proxy::Proxy> proxy =
-        libmexclass::proxy::ProxyManager::getProxy(proxy_id);
+    auto proxy = libmexclass::proxy::ProxyManager::getProxy(proxy_id);
+
+    if (!proxy) {
+        return libmexclass::error::Error{"libmexclass:proxy:UnknownProxyID", "Unknown proxy ID " + std::to_string(proxy_id)};
+    }
 
     // Invoke the appropriate method on the proxy::Proxy instance.
     // Note: To assign/return outputs from a method call, proxy::Proxy

libmexclass/cpp/source/libmexclass/proxy/ProxyManager.cpp

@@ -13,7 +13,12 @@ void ProxyManager::unmanageProxy(ID id) {
 }
 
 std::shared_ptr<Proxy> ProxyManager::getProxy(ID id) {
-    return ProxyManager::singleton.proxy_map[id];
+    auto proxy_key_value = ProxyManager::singleton.proxy_map.find(id);
+    if (proxy_key_value != ProxyManager::singleton.proxy_map.end()) {
+        return proxy_key_value->second;
+    } else {
+        return nullptr;
+    }
 }
 
 ProxyManager ProxyManager::singleton{};