Hello Michel,
On 2009-02-02 01:39:40 -0500, John Reimer <terminal.n...@gmail.com>
said:
"The Objective-C language defers as much as it can from compile time
and link time to runtime. Whenever possible, it does things
dynamically. This means that the language requires not just a
compiler, but also a runtime system to execute the compiled code.
The runtime system acts as a kind of operating system for the
Objective-C language; it's what makes the language work."
This is actually kind of interesting because it would seem to make
Objective-C slightly comparable to the C# language in that it's more
than just a language (as is Java). It's a platform (and the beauty
of the platform is really only extensively demonstrated by the OS
runtime functionality that supports it ... and Cocoa).
Yeah, but the Objective-C runtime is pretty microscopic compared to
Java or the C# runtime. There is no such thing as a virtual machine.
What the Objecitve-C runtime does is this, and only this:
1. It manages a list of registered classes, and their associated
methods.
2. It provides a method dispatch mechanism, and manages a list of
registered selectors.
3. It provides various support routines for the compiler (exception
handling, synchronization).
For comparison, the D runtime does half of 1, and whole of 3, and a
lot more. If you start counting parts of the Foundation framework in
the runtime, then you'd have a base object class, an exception class,
a thread class... But technically, Foundation is not part of the
runtime, even if it's pretty necessary to do anything.
I see... But the dynamic binding part is part of one, I assume? That's a
pretty big (in terms of importance) feature that seems lacking in other runtimes?
I don't know if C# provides anything like it.
I'd say that the Objective-C runtime is smaller than druntime since it
does less (no TypeInfo, no array concat, no associative array, no
thread support, etc.), although I haven't measured anything. On the
other hand, the "standard library" (the Foundation framework) is
probably bigger than both Phobos and Tango together.
Ok, thanks for the info. I think with Objective C, it's more about what
it achieves than how much. The Objective C people seem to make a fairly
big deal about how dynamic binding makes the language so much more flexible
than other languages (which probably is true) in this one regard.
-JJR
