Are C#'s partial classes bad design? [closed]

Answer 1

There's a lot of discussion out there on this topic, and lots of people saying that 1) it's bad design to use partial classes, 2) that it's used for autogenerated code, and 3) that it shouldn't take the place of inheritance.

I have a situation, though, in which partial classes look like they'll come in very handy: I'm building a series of applications which will eventually be integrated into a suite. They'll all have a main form which will provide some functionality, and several shared components (e.g., a form to display reports). While I could define a base class and inherit from it, that would mean a lot of rework when the time comes to combine all of the applications into the "enterprise" version of the product.

Thus, partial classes are quite useful, because I can quite simply include the various partial classes into the combined version, while still allowing me to build the individual, stand-alone versions of the product. If I were to try to accomplish this using inheritance, I'd end up with each component calling its own version of the common components (e.g., InvoiceReportViewer, PurchasingReportsViewer, etc.) rather than simply calling ReportsViewer and knowing that Visual Studio will have integrated all of the bits for me.

Answer 2

Another good use for partial classes would be when implementing the Abstract factory pattern. Make the root factory object partial and then place the actual factory methods in the same file as the class the factory instantiates.

EDIT: Partial classes also work well for classes that interact with a configuration file. Place the code containing the configuration parameters near the code that actually uses the configuration parameter.

Answer 3

Just stumbled across this thread while googling the benefits of partial class. I am in the process of converting a Java EE application into a silverlight based .NET one. I came across the following code in the view layer :

//------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by a tool.
//     Runtime Version:4.0.30319.225
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------

...

 public partial class Wwcusts04d : System.Windows.Controls.Page {

Now, if the partial page itself is autogenerated, what's the use of maintaining it ? Also, the code inside just links various controls to their names. I don't confess to have knowledge of silverlight, but isnt this thing better suited in xaml?