BREAKING

dplug:host API has changed to be nothrow @nogc and avoid exceptions. This is the last part of the Dplug API which used a D runtime.
This that wasn't a high quality API in the first place, unless you use dplug:host you probably have nothing to fear.
- createPluginHost can now return null, must be paired with destroyPluginHost who also closes the dynlib
- host.close(); is deprecated
- saveChunk / restoreChunk now report failure
- string getters such host.getParameterName now return a const(char)[] string, zero-terminated, owned by dplug:host
- no more global reverse map in VST hosting

host/dplug/host/host.d

@@ -5,8 +5,12 @@ License:   $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
 */
 module dplug.host.host;
 
+nothrow @nogc:
+
 interface IPluginHost
 {
+nothrow @nogc:
+
     /// Process some audio.
     /// `setSampleRate` and `setMaxBufferSize` must be called before use.
     /// samples must <= the maximum buffer size asked in 
@@ -28,6 +32,7 @@ interface IPluginHost
     float getParameter(int paramIndex);
 
     /// Returns: Full name for parameter.
+    /// Lifetime of return value is same as IPluginHost.
     const(char)[] getParameterName(int paramIndex);
 
     /// Returns: Number of parameters.
@@ -36,26 +41,32 @@ interface IPluginHost
     /// Loads a preset.
     void loadPreset(int presetIndex);
 
-    /// Serialize state of the plugin.
-    ubyte[] saveState();
+    /// Serialize state of the plugin, to restore with `restoreState`.
+    ///
+    /// Returns: `null` in case of error, else a state chunk.
+    ///           The lifetime of this returned chunk is the same as the `IPluginHost`, or until 
+    ///           another call to `saveState` is done.
+    const(ubyte)[] saveState();
 
-    /// Restore state of the plugin.
-    void restoreState(ubyte[] chunk);
+    /// Restore state of the plugin, saved with `saveState`.
+    /// Returns: `true` on success.
+    bool restoreState(const(ubyte)[] chunk);
 
     /// Gets current "program" index.
+    /// Note: not all presets are exposed to the host. In many plug-ins they aren't.
     int getCurrentProgram();
 
-    /// Free all resources associated with the plugin host.
-    void close();
-
-    /// Get plugin information
-    string getProductString();
+    /// Get plugin information.
+    /// Lifetime of return value is same as IPluginHost.
+    const(char)[] getProductString();
 
     ///ditto
-    string getEffectName();
+    /// Lifetime of return value is same as IPluginHost.
+    const(char)[] getEffectName();
 
     ///ditto
-    string getVendorString();
+    /// Lifetime of return value is same as IPluginHost.
+    const(char)[] getVendorString();
 
     /// Opens the editor window.
     /// On Windows, pass a HWND
@@ -82,6 +93,8 @@ interface IPluginHost
 
     /// Get tail size in seconds. Precise semantics TBD.
     double getTailSizeInSeconds();
+
+    deprecated("Use destroyPluginHost() instead") void close();
 }
 
 

host/dplug/host/package.d

@@ -12,8 +12,11 @@ public import dplug.host.host;
 public import dplug.host.vst2;
 public import dplug.host.window;
 
+nothrow @nogc:
+
 /// Loads an audio plugin.
 /// Such a host MUST be destroyed with `destroyPluginHost`.
+/// Return: a plugin host, or `null` on error.
 IPluginHost createPluginHost(string dynlibPath)
 {
     // FUTURE support OSX plugin bundles
@@ -26,13 +29,20 @@ IPluginHost createPluginHost(string dynlibPath)
     {
         version(VST2)
         {
-            return new VST2PluginHost(lib.disown);
+            bool err;
+            VST2PluginHost instance = mallocNew!VST2PluginHost(lib.disown, &err);
+            if (err)
+            {
+                destroyFree(instance);
+                return null; // TODO: shall call destructor?
+            }
+            return instance;
         }
         else
-            throw new Exception("Couldn't load plugin: VST 2.4 format not supported");
+            return null; // VST 2.4 not supported
     }
     else
-        throw new Exception("Couldn't load plugin: unknown format");
+        return null; // unknown format
 }
 
 /// Destroy a plugin host created with `createPluginHost`.