How easy is it to port a Windows Phone 7 application to Metro on a Windows 8 tablet?

Question

I know that Metro on both platforms shares a common “look and feel” and that WinRt makes use of XAMLand C# (or VB.NET) like Silverlight does on Windows Phone 7.

Howev

Answer 1

Despite certain people in Microsoft claiming it will only require changing a couple of lines of code...

The only possible answer to how difficult it will be to port an app is IT DEPENDS!

• What does the phone app do?
• How much of that functionality is also available on Win8?
• What should be done done when it's not possible to do the same thing on Win8?
• What should additionally be added (if anything) to the Win8 version?
• What are you going to do with the extra screen real estate that you have on Win8 compared with the phone?
• Are you using controls or UI elements on one which don't exist on the other?
• etc, ....

The parrallels are that:

• both use XAML
• both can use the same programming language for the code (probably C#)
• the design of "metro style" apps on Win8 was INSPIRED by Metro (the design language of WP7)

beyond that it will depend on the app.

You can't create an app which will run on both. At the very least you'll need to recompile as the 2 platforms will require targetting different versions of the .net framework.

Update:
Microsoft have provided some early stage guidance on making such a port. It includes some namespace and API mappings.