[Openmcl-devel] Building the ApplicationServices framework

[Gary Byers]

On Fri, 27 Jun 2008, Didier Verna wrote:

> I wrote:
>
>>> I'm not really sure that that's necessary, since Cocoa.h seems to (via
>>> a twisty maze of #include's, all alike ...) already include
>>> ApplicationServices.h. (I may be mistaken about that, but that's my
>>> recollection.)
>>
>>    Hmmm, I had to use things like CGColorGetConstantColor and
>>  kCGColorBlack and stuff, but CCL complained it didn't know these things.
>>  So I read Apple's dev documentation and figured out it was part of the
>>  ApplicationServices framework...
>
>   which seems to be confirmed by the fact that I can't find the string
> kCGColorBlack in any of the already existing constants.cdb files,
> contrary to, say, kGenericFolderIcon.
>
> I do see it in vars.cdb files though. What does this mean ?

It means that it's a variable and not a constant.

? #&kCGColorBlack
#<NS-MUTABLE-STRING "kCGColorBlack" (#x7FFF7078FE40)>

In MacOSX, a lot of things that are conceptually constant (immutable)
but whose initial values are objects (either at the CoreFoundation
level or the ObjC level) are variables (and a lot of those objects
are NSStrings/CGStrings.)

You generally don't want to do so, but you can meaningfully assign
values to foreign variables.  If the traditional C "errno" was
a simple global variable - it's usually something thread-specific
these days - you could write code like:

;;; This won't realy work; it's just a bad example ...

? (setq #&errno 0)

;;; I don't know if this will work, or what effect it'll have if it does.

? (psetq #&kCGColorBlack #&kCGColorWhite)