Re: "weak link" framework refs for 10.1 compatibility?

FROM : Marco Scheurer
DATE : Sat Nov 09 16:40:37 2002

On Friday, November 8, 2002, at 11:17 AM, Bill Cheeseman wrote:
> The bottom line, as I understand it, is that an application using C
> constants that are new in 10.2 will not launch in 10.1.x or earlier.
> Checking the system version to branch around them will not work,
> because the
> loader tries to load them all at once, up front.

Is that true? The following code, in a category of NSTextField,
compiled on 10.2 does not break on 10.1.x (text field is not rounded).

- (void) beRounded
{
   if (IsJaguarOrLater()) {
       [self setBezeled:YES];
       [self setBezelStyle:NSTextFieldRoundedBezel];
   }
}

Not only the NSTextFieldRoundedBezel constant, but also the
setBezelStyle method are new to 10.2. These are defined in
NSTextFieldCell and NSTextField like this:

#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_2
typedef enum {
    NSTextFieldSquareBezel  = 0,
    NSTextFieldRoundedBezel = 1
} NSTextFieldBezelStyle;
#endif


#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_2
- (void)setBezelStyle:(NSTextFieldBezelStyle)style;
- (NSTextFieldBezelStyle)bezelStyle;
#endif


And IsJaguarOrLater uses Gestalt to get the OS version:

BOOL IsJaguarOrLater()
{
   unsigned long os_version = 0;
   Gestalt (gestaltSystemVersion, &os_version);
   return (os_version >= 0x1020);
}

Marco Scheurer
Sen:te, Lausanne, Switzerland    http://www.sente.ch
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