add cpp-lib example; some fixes

cpp-lib/cpp/cpp.pro

@@ -0,0 +1,14 @@
+QT          += core
+TEMPLATE    = lib
+CONFIG      += plugin release
+DESTDIR     = ../
+TARGET      = cpp
+OBJECTS_DIR = ./tmp/
+MOC_DIR     = ./tmp/
+
+win32 {
+  include(../../src/windows.pri)
+}
+
+HEADERS += lib.h
+SOURCES += lib.cpp

cpp-lib/cpp/lib.cpp

@@ -0,0 +1,27 @@
+#include "lib.h"
+#include <QtDebug>
+
+QT_BEGIN_NAMESPACE
+
+QObject* ini() {
+  // any QObject inherited class will do
+  static QObject* cpp = 0;
+  if(!cpp) {
+    cpp = new CPP;
+  }
+  return cpp;
+}
+
+// insert here your function implementations
+
+QVariant CPP::hello(const QVariant& arg) {
+  QString msg;
+  QDebug debug(&msg);
+  debug << arg;
+
+  qDebug() << "hello" << arg;
+
+  return arg;
+}
+
+QT_END_NAMESPACE

cpp-lib/cpp/lib.h

@@ -0,0 +1,28 @@
+#ifndef LIB_H
+#define LIB_H
+
+#include <QtCore>
+
+#ifdef Q_CC_MSVC
+#define LIB_EXPORT __declspec(dllexport)
+#else
+#define LIB_EXPORT
+#endif
+
+QT_BEGIN_NAMESPACE
+
+extern "C" { LIB_EXPORT QObject* ini(); }
+
+class CPP : public QObject
+{
+  Q_OBJECT
+
+public:
+  // max. 10 arguments of type QVariant
+  // return type must also be a QVariant
+  Q_INVOKABLE QVariant hello(const QVariant&);
+};
+
+QT_END_NAMESPACE
+
+#endif

cpp-lib/readme.md

@@ -0,0 +1,39 @@
+
+Build
+-----
+
+Switch to `cpp/` and do:
+```
+qmake lib.pro
+make
+```
+
+
+Run
+---
+
+```
+$ lqml ~/slime/qml-start-swank.lisp
+$ emacs
+```
+
+In Slime do:
+```
+(defvar *cpp* (qload-c++ "cpp"))
+
+(define-qt-wrappers *cpp*)
+
+(hello *cpp* '(1 "two" (1.25 #(50 -50 75))))
+```
+Now look at the console output where you launched the `lqml` executable.
+
+As you can see, although the argument and return type are simply defined as
+`QVariant`, you may also pass lists, because a `QVariant` can also be of type
+`QVariantList`, so this is a perfect fit for (nested) Lisp lists.
+
+So, we pass a nested Lisp list, and it gets printed on Qt side with the
+respective types. Then the `QVariantList` is returend to Lisp, where it is
+automatically converted back to a nested Lisp list.
+
+Realy convenient!
+

cpp-lib/run.lisp

@@ -0,0 +1,6 @@
+(defvar *cpp* (qload-c++ "cpp"))
+
+(define-qt-wrappers *cpp*)
+
+(print (hello *cpp* '(1 "two" (1.25 #(50 -50 75)))))
+