Interesting side note. As I understand it, try-catch is no longer expensive in the case where no error is thrown. I explained to someone why I didn't want to use a try-catch in some performance critical code, and I cited Jackson Dunstan's article. They ran the benchmark from the article in a newer runtime, and the big performance difference was gone. I was able to confirm on my machine.
Regardless, I would never wrap a function-style cast in a try-catch. Not my style. If I expect it might fail, I check with "is" first, or, sometimes, use an as-style cast instead and check for null. To be honest, my memory of the performance difference between casting styles is from 6-8 years ago, so my knowledge may be as out of date as the try-catch thing. Or maybe I'm completely misremembering after so many years. I've had a few cases where that's true, like the whole toString() thing the other day. - Josh On Jan 7, 2016 8:07 PM, "Andy Dufilie" <andy.dufi...@gmail.com> wrote: > On Thu, Jan 7, 2016 at 10:54 PM, Josh Tynjala <joshtynj...@gmail.com> > wrote: > > > That's odd. I swear I remember someone from Adobe once explaining that > > function-style casting is faster than as-style casting (with the > exception > > of primitive types that have a top level function that makes > function-style > > casting impossible, as you mentioned in 1). I've tried to avoid as-style > > casting for years, based on this knowledge. > > > > - Josh > > > > See this stack overflow answer and the articles it links: > http://stackoverflow.com/a/14268394 > > *EDIT:* concerning performance, using as is reported to be faster than the > > function call style casting in various articles: [1 > > <http://jacksondunstan.com/articles/830>] [2 > > <http://upshots.org/actionscript/20-tips-to-optimize-your-actionscript>] > [ > > 3 > > < > http://gamedevjuice.wordpress.com/2008/02/15/seven-tips-about-performance-optimization-in-actionscript-3/ > >]. > > The first article cited looks at the performance differences in depth and > > reports that as is 4x-4.5x faster. > > > > *EDIT 2:* Not only is as 4x-4.5x faster in the normal best case, but when > > you wrap the (cast) style conversion in a try-catch block, and an error > > actually ends up being thrown, it's more like 30x - 230x faster. In AS3, > if > > you think you're going to do something exceptional (in that it could > throw > > an error) then it's clear that you should always look before you leap. > > Never use try/catch unless forced to by the API, and indeed that means to > > never (cast) It also is instructive to look at the performance > > implications of try/catch even when no exception is thrown. There's a > > performance penalty to setting up a try/catch block even in the happy > case > > that nothing goes wrong. > > > > >
