What are the pros and cons of migrating an application from Flex3 to Flex 4?

I had many issues found in migration from Flex 3 to Flex 4. I had done some logic in flex 3 but while migrating the same code to flex4 it is not working. Please help me out how to do the ex开发者_如何学运维act migrating or have any tool for migrating the code from flex3 to flex 4.

There are many advantages of Flex 4, one of which is Skinning, which is a huge plus for code reuse but also separation of concerns (separate the view/styling from the component behavior). There's also FXG (mxml based vectors) that can be used with Catalyst to easily skin components from illustrator.

Flex 4 is definitely the future and what you should strive for, but it does bring forth a lot of changes, so the con here is that it's very hard to convert a Flex 3 app to Flex 4 without redoing some code. It's a different mentality altogether and it needs to be adhered.

There are no quick tool to convert your component logic.

On my expirience most of the things I had to fix on my project when migrated to Flex 4 were related to parts of code that were actually work arounds for some strange behaviour with scaling/resizing of components in Flex 3, which was resolved in Flex 4. Overly it wasn't hard, there are no major changes in logic, just improvements and some bugs fixed, and possibly few new bugs made :)

When migrating to Flex 4 it's not neccessary to change your components to Spark ones, you can still use your MX structure. New components use a different layout, you build them a bit differently * you cant use Spark's ComboBox/DropDownList as in MX, since you need IList objects as data provider * Resize/Scale and measures work as they should now, in both MX and Spark components * you can't add directly some of MX components to Spark containers as you could in Flex 3 * you use addElement instead addChild for Spark components * in Flex 4 they introduced FTE, with superior text render quality, lifting the limit of 127px font size, but now if you embed fonts on runtime (I do) you have to use CFF flag

I think that migrating to Flex 4 worth the hassle, just if you decide to use the latest SDK build (4.5) you may encounter some issues, 4.1 is a safer call at the moment, tho I'm using 4.5 knowing of the risks.