Rewrite the path through NyquistEffect, in the case that...

... you use the prompt, and you enter a complete script with control comments
that are reinterpreted to put up a second dialog.

This simplifies Effect::Delegate() and avoids mutual recursion of ShowInterface
with DoEffect.

src/effects/ChangePitch.cpp

@@ -215,7 +215,7 @@ bool EffectChangePitch::Process()
       proxy.mProxyEffectName = XO("High Quality Pitch Change");
       proxy.setParameters(1.0, pitchRatio);
 
-      return Delegate(proxy, *mUIParent, nullptr);
+      return Delegate( proxy );
    }
    else
 #endif

src/effects/ChangeTempo.cpp

@@ -200,7 +200,7 @@ bool EffectChangeTempo::Process()
       EffectSBSMS proxy;
       proxy.mProxyEffectName = XO("High Quality Tempo Change");
       proxy.setParameters(tempoRatio, 1.0);
-      success = Delegate(proxy, *mUIParent, nullptr);
+      success = Delegate( proxy );
    }
    else
 #endif

src/effects/Effect.cpp

@@ -1218,14 +1218,13 @@ bool Effect::DoEffect(double projectRate,
    return returnVal;
 }
 
-bool Effect::Delegate(
-   Effect &delegate, wxWindow &parent, const EffectDialogFactory &factory )
+bool Effect::Delegate( Effect &delegate )
 {
    NotifyingSelectedRegion region;
    region.setTimes( mT0, mT1 );
 
-   return delegate.DoEffect( mProjectRate, mTracks, mFactory,
-      region, &parent, factory );
+   return delegate.DoEffect(
+      mProjectRate, mTracks, mFactory, region );
 }
 
 // All legacy effects should have this overridden

src/effects/Effect.h

@@ -261,8 +261,7 @@ class AUDACITY_DLL_API Effect /* not final */ : public wxEvtHandler,
       wxWindow *pParent = nullptr,
       const EffectDialogFactory &dialogFactory = {} );
 
-   bool Delegate( Effect &delegate,
-      wxWindow &parent, const EffectDialogFactory &factory );
+   bool Delegate( Effect &delegate );
 
    virtual bool IsHidden();
 

src/effects/nyquist/Nyquist.cpp

@@ -523,6 +523,8 @@ bool NyquistEffect::SetAutomationParameters(CommandParameters & parms)
 
 bool NyquistEffect::Init()
 {
+   mDelegate.reset();
+
    // When Nyquist Prompt spawns an effect GUI, Init() is called for Nyquist Prompt,
    // and then again for the spawned (mExternal) effect.
 
@@ -596,17 +598,21 @@ bool NyquistEffect::Init()
    return true;
 }
 
-bool NyquistEffect::CheckWhetherSkipEffect()
-{
-   // If we're a prompt and we have controls, then we've already processed
-   // the audio, so skip further processing.
-   return (mIsPrompt && mControls.size() > 0);
-}
-
 static void RegisterFunctions();
 
 bool NyquistEffect::Process()
 {
+   if (mDelegate)
+   {
+      mProgress->Hide();
+      auto &effect = *mDelegate;
+      auto result = Delegate( effect );
+      mT0 = effect.mT0;
+      mT1 = effect.mT1;
+      mDelegate.reset();
+      return result;
+   }
+   
    // Check for reentrant Nyquist commands.
    // I'm choosing to mark skipped Nyquist commands as successful even though
    // they are skipped.  The reason is that when Nyquist calls out to a chain,
@@ -626,10 +632,6 @@ bool NyquistEffect::Process()
    EffectManager & em = EffectManager::Get();
    em.SetSkipStateFlag(false);
 
-   if (mExternal) {
-      mProgress->Hide();
-   }
-
    mOutputTime = 0;
    mCount = 0;
    mProgressIn = 0;
@@ -992,14 +994,14 @@ bool NyquistEffect::ShowInterface(
       return res;
    }
 
-   NyquistEffect effect(NYQUIST_WORKER_ID);
-
+   // Come here only in case the user entered a script into the Nyquist
+   // prompt window that included the magic comments that specify controls.
+   // Interpret those comments and put up a second dialog.
+   mDelegate = std::make_unique< NyquistEffect >( NYQUIST_WORKER_ID );
+   auto &effect = *mDelegate;
    effect.SetCommand(mInputCmd);
    effect.mDebug = (mUIResultID == eDebugID);
-   bool result = Delegate(effect, parent, factory);
-   mT0 = effect.mT0;
-   mT1 = effect.mT1;
-   return result;
+   return effect.ShowInterface( parent, factory, forceModal );
 }
 
 void NyquistEffect::PopulateOrExchange(ShuttleGui & S)

src/effects/nyquist/Nyquist.h

@@ -97,7 +97,6 @@ public:
    // Effect implementation
 
    bool Init() override;
-   bool CheckWhetherSkipEffect() override;
    bool Process() override;
    bool ShowInterface( wxWindow &parent,
       const EffectDialogFactory &factory, bool forceModal = false) override;
@@ -189,6 +188,8 @@ private:
 
 private:
 
+   std::unique_ptr<NyquistEffect> mDelegate;
+
    wxString          mXlispPath;
 
    wxFileName        mFileName;  ///< Name of the Nyquist script file this effect is loaded from