Show more descriptive error message for exceptions while loading plugins

[gkronber]

r8178: throwing a more informative exception when loading a plugin fails because it's assemblies are not loaded.

[gkronber]

The reported exception can only occur when all assemblies of the plugin can be loaded into the reflection-only and in the execution context in an earlier step but later in LoadPlugins the assemblies are not found in the list of assemblies loaded in the current AppDomain. Since we are comparing assemblies by location maybe this can happen if one of our assemblies is also residing in the GAC and loaded from there instead? This has to be analyzed in more detail...

More detailed information: in line 550 of PluginValidator.cs

List<Assembly> assemblies = 
  new List<Assembly>(AppDomain.CurrentDomain.GetAssemblies());
foreach (var desc in pluginDescriptions) {
  if (desc.PluginState == PluginState.Enabled) {
    // cannot use ApplicationManager to retrieve types because 
    // it is not yet instantiated
    foreach (string assemblyLocation in desc.AssemblyLocations) {
      var asm = (from assembly in assemblies
                 where string.Equals(Path.GetFullPath(assembly.Location), 
                                     Path.GetFullPath(assemblyLocation),
                                     StringComparison.CurrentCultureIgnoreCase)
                 select assembly)
                 .SingleOrDefault();
     if (asm == null) 
       throw new InvalidPluginException("Could not assembly " + assemblyLocation + 
                                        " for plugin " + desc.Name);

[gkronber]

Reproduced the problem by installing Mono.Cecil.dll to the GAC.

[gkronber]

r8193: fixed a problem in plugin loading which occurs if one of the assemblies shipped with HeuristicLab is already installed in the GAC of the machine.

[abeham]

Okay, I looked at the change r8193. So instead of relying on a path reference to identify the assembly you're now comparing them by their full name.

The exception message in line 559 in PluginValidator.cs reads "Could not assembly " + assemblyName + " for plugin " + desc.Name. It says assembly when you probably meant "find" or "locate".

[gkronber]

r8200: fixed exception message

[abeham]

thx