We should have errors for at least the following:

memory allocation
plugin specific failure
invalid input

It would also be useful to be able to return a string that gives more information about the error, and which could be displayed in the debug log.

Will add support for returning a string shortly, then close.

CVS commit by staikos: 

1) get rid of symbol warnings in KstDataSource
2) add support for custom strings in plugin errors
BUG: 88086


  M +5 -1      kstdatasource.cpp   1.45
  M +10 -0     kstplugin.cpp   1.77
  M +10 -0     plugin.cpp   1.28
  M +2 -1      plugin.h   1.33
  M +4 -0      pluginloader.cpp   1.16


--- kdeextragear-2/kst/kst/kstdatasource.cpp  #1.44:1.45
@@ -143,5 +143,9 @@ namespace KST {
         // FIXME: might be a good idea to cache this per-symbol
 
-        return _lib->symbol(QFile::encodeName(sym + "_" + _plugLib));
+        QCString s = QFile::encodeName(sym + "_" + _plugLib);
+        if (_lib->hasSymbol(s)) {
+          return _lib->symbol(s);
+        }
+        return 0L;
       }
 

--- kdeextragear-2/kst/kst/kstplugin.cpp  #1.76:1.77
@@ -323,4 +323,14 @@ KstObject::UpdateType KstPlugin::update(
     }
     _lastError = QString::null;
+  } else if (rc > 0) {
+    if (_lastError.isEmpty()) {
+      const char *err = _plugin->errorCode(rc);
+      if (err && *err) {
+        _lastError = err;
+        KstDebug::self()->log(i18n("Plugin %1 produced error: %2.").arg(tagName()).arg(_lastError), KstDebug::Error);
+      } else {
+        _lastError = QString::null;
+      }
+    }
   } else {
     bool doSend = _lastError.isEmpty() ? true : false;

--- kdeextragear-2/kst/kst/plugin.cpp  #1.27:1.28
@@ -30,4 +30,5 @@ Plugin::Plugin() : KstShared() {
   _symbol = 0L;
   _freeSymbol = 0L;
+  _errorSymbol = 0L;
   _parameterName = 0L;
   //kdDebug() << "Creating Plugin: " << long(this) << endl;
@@ -38,4 +39,5 @@ Plugin::~Plugin() {
   _symbol = 0L;
   _freeSymbol = 0L;
+  _errorSymbol = 0L;
   _parameterName = 0L;
 
@@ -198,3 +200,11 @@ bool Plugin::freeLocalData(void **local)
 }
 
+
+const char *Plugin::errorCode(int code) const {
+  if (_errorSymbol) {
+    return ((const char *(*)(int))_errorSymbol)(code);
+  }
+  return 0L;
+}
+
 // vim: ts=2 sw=2 et

--- kdeextragear-2/kst/kst/plugin.h  #1.32:1.33
@@ -58,4 +58,5 @@ class Plugin : public KstShared {
     QString parameterName(int index) const;
     bool freeLocalData(void **local) const;
+    const char *errorCode(int code) const;
 
     static const int CallError;
@@ -143,5 +144,5 @@ class Plugin : public KstShared {
     KLibrary *_lib;
 
-    void *_symbol, *_freeSymbol;
+    void *_symbol, *_freeSymbol, *_errorSymbol;
     void *_parameterName;
 

--- kdeextragear-2/kst/kst/pluginloader.cpp  #1.15:1.16
@@ -76,4 +76,8 @@ Plugin *PluginLoader::loadPlugin(const Q
   }
 
+  if (plug->_lib->hasSymbol("errorCode")) {
+    plug->_errorSymbol = plug->_lib->symbol("errorCode");
+  }
+
   if (!plug->_symbol) {
     KstDebug::self()->log(i18n("Could not find symbol '%1' in plugin %2.").arg(plug->_data._name).arg(object), KstDebug::Error);