Is it a good practice to perform initialization within a Property?

Question

I have a class PluginProvider that is using a PluginLoader component to load plugins (managed/native) from the file system. Within the PluginProvider class, there is currently defined a property called 'PluginTypes' which calls the 'InitializePlugins' instance method on get().

class PluginProvider
 {
   IEnumerable<IPluginType> PluginTypes
   {
     get
     {
        //isInitialized is set inside InitializePlugins method
        if(!isInitialized)
        {
           InitializePlugins(); //contains thread safe code
        }
        //_pluginTypes is set within InitializePlugins method
        return _pluginTypes;
     }
   }
 }

I am looking at refactoring this piece of code. I want to know whether this kind of initialization is fine to do within a property. I know that heavy operations must not be done in a property. But when i checked this link : http://msdn.microsoft.com/en-us/library/vstudio/ms229054.aspx , found this " In particular, operations that access the network or the file system (other than once for initialization) should most likely be methods, not properties.". Now I am a bit confused. Please help.

Answer 1

This is of course a matter of taste. But what i would do depends on the length of the operation you're trying to perform. If it takes time to load the plugins, i would create a public method which any user would need to call before working with the class. A different approach would be to put the method inside the constructor, but IMO constructors should return as quickly as possible and should contain field / property initialization.

class PluginProvider
{
    private bool _isInitialized;
    IEnumerable<IPluginType> PluginTypes { get; set;}

    public void Initialize()
    {
        if (_isInitialized)
        {
             return;
        }      

        InitializePlugins();
        _isInitialized = true;  
    }
}

Note the down side of this is that you will have to make sure the Initialize method was called before consuimg any operation.

Another thing that just came to mind backing this approach is exception handling. Im sure you wouldn't want your constructorcto be throwing any kind of IOException in case it couldn't load the types from the file system.