add convenience function EQL::addObject() for adding Qt class instances as Lisp variables

Qt_EQL/tutorial/main.cpp

@@ -11,13 +11,13 @@ int main(int argc, char* argv[]) {
     main->resize(600, 400);
     main->show();
 
-    // we need an instance for 'define-qt-wrappers' and 'new-instance' to work;
-    // we pass the main widget as parent and a unique 'objectName', so we can
-    // find it from Lisp
-
-    Test test(main, "test");
-
     EQL eql;
+
+    // add desired Qt class instances as Lisp variables (uses 'defvar'):
+
+    EQL::addObject(main,           "eql-user:*main-widget*");
+    EQL::addObject(new Test(main), "eql-user:*test*");
+
     EQL::eval("(in-package :eql-user)");
     EQL::eval("(load \"test.lisp\")");   // will start a REPL
     app.processEvents();                 // needed for 'qlater' in 'test.lisp'

Qt_EQL/tutorial/test.h

@@ -7,17 +7,19 @@
 class Test : public QObject {
     Q_OBJECT
 public:
-    Test(QObject*, const QString&);
+    Test(QObject* = nullptr, const QString& = QString());
 
     // define function acting as constructor (callable from Lisp)
     // N.B. return a vanilla Qt class (here: QObject*) known to EQL5
-    Q_INVOKABLE QObject* newInstance(QObject*, const QString&);
+    Q_INVOKABLE QObject* newInstance(QObject* = nullptr, const QString& = QString());
 
 public Q_SLOTS:
-    // you may pass any type found in '~/eql5/src/ecl_fun.cpp::toMetaArg()'
+    // you may pass any type found in '~/eql5/src/ecl_fun.cpp::toMetaArg()';
+    // it's common practice in Qt to always pass const references (except for
+    // pointers, of course), as you'll find in any Qt example code
     QString concat(const QStringList&);
 
-    // pass Lisp data
+    // pass Lisp data ('cl_object' is just a pointer)
     void processData(cl_object);
 
     // call back to Lisp

Qt_EQL/tutorial/test.lisp

@@ -1,11 +1,5 @@
 (in-package :eql-user)
 
-;; find main widget of app
-(defvar *main-widget* (first (|topLevelWidgets.QApplication|)))
-
-;; find 'Test' instance by its 'objectName'
-(defvar *test* (qfind-child *main-widget* "test"))
-
 ;; the following defines generic functions for all Qt signals,
 ;; Qt slots and functions declared Q_INVOKABLE
 

src/eql.cpp

@@ -215,6 +215,16 @@ void EQL::exec(QWidget* widget, const QString& lispFile, const QString& slimeHoo
     if(exec_with_simple_restart) {
         eval("(eql::exec-with-simple-restart)"); }}
 
+void EQL::addObject(QObject* object, const QByteArray& varName) {
+    int p = varName.indexOf(':');
+    QByteArray pkg = (p == -1) ? "eql-user" : varName.left(p);
+    QByteArray var = varName.mid(varName.lastIndexOf(':') + 1);
+    cl_object l_symbol = cl_intern(2,
+                                   STRING_COPY(var.toUpper().constData()),
+                                   cl_find_package(STRING_COPY(pkg.toUpper().constData())));
+    cl_object l_object = qt_object_from_name(LObjects::vanillaQtSuperClassName(object->metaObject()), object);
+    ecl_defvar(l_symbol, l_object); }
+
 void EQL::runOnUiThread(void* function_or_closure) {
     const cl_env_ptr l_env = ecl_process_env();
     CL_CATCH_ALL_BEGIN(l_env) {

src/eql5/eql.h

@@ -42,6 +42,7 @@ public:
     static void ini(int, char**);
     static void ini(char**);
     static void eval(const char*, const EvalMode = evalMode);
+    static void addObject(QObject*, const QByteArray&);
     static EvalMode evalMode;
 
     void exec(const QStringList&);