Slashdot Mirror

Nice link on Reflection, every now and then I wish I could do that but didn't know I could.

There's a lot more to it if you dig deeper:
Objective-C Runtime Programming Guide

You can do some pretty neat stuff like dynamically creating a class and adding methods to it. Some of it should only be used as a last resort but it's nice having the tools at hand if you really need them. This kind of stuff is either extremely difficult or outright impossible in C++.

Yes, there are some performance penalties to a dynamic runtime but for most cases it is negligible. If you desire you can circumvent the dynamic aspect of Objective-C and "freeze" method calls in order to get around those penalties for performance-critical code. There's a great series of articles on this subject: The Optimizing Objective C Series

Objective-c message passing is quite fast, only 4x the cost of a virtual table call in C++

Not to mention you could use a method implementation pointer (another good site) to skip all of the behind-the-scenes dynamic dispatch and then you are right around the speed of a normal C function call. Objective-C lets you have the ease of message passing when you want it and the speed of C function calls when you need it.

These results mirror what I typically see on my workstation. I run a couple of websites on my workstation including our laboratory website, and my blog. Logs are monitored constantly with a nice tool called mkconsole that displays the logs transparently on my desktop. Several times a week, there is an attack. Most however are either scripted or fairly primitive, although last week there was a sophisticated attack that that bounced through a compromised Windows machine on campus. We tracked it back to an AOL user on the East coast and reported his IP address to the sysadmins. They sent an email back to me letting me know that they would follow it up. I've not heard anything else since, but in addition to using a more secure OS, one should also maintain a vigilance of your systems to help keep things under control and if you do use Windows, PLEASE keep it patched with recent security releases.

The truth is that if somebody really does want to get into your system, it can happen. In addition to using a secure OS and keeping the security updates current, securing physical access is your next line of defense.

Another response already addressed prebinding, so I'll just add this...

Plain old C links just fine with Objective-C, so optimize that 5% of code that's causing 95% of your performance bottleneck in C, if you like. Meantime the features of Objective-C and Cocoa/GNUStep have (hopefully!) made you more productive, either getting you to market quicker or giving you the time and tools to add more bells and whistles.

There are also ways to optimize Objective-C code to do stuff like taking the call overhead out of loops.

All tools have their tradeoffs, and choosing the right tool and optimization strategy is part of the game. If raw performance were the sole criteria for choosing a development tool, we'd all be using assembly language. ;)

If DirecX becomes the only modern graphics library available, we have lost much from our freedom. If all popular computer entertainment would use DirectX, think about the power Microsoft would have.

As long as people keep making good OpenGL games - such as the recent uDevGames contest winner - were safe.

*lbtr

Here is an open source (LGPL) XML-RPC framework that advertises itself as a drop-in replacement for Cocoa's NSConnection object.