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Detecting Classic and Carbon X Environments




Q: My application does things that just won't work in the Classic environment. How do I detect the Classic environment so that I can tell the user why certain functionality has been disabled?

A: You can detect the Classic environment using Gestalt, as shown in Listing 1.

// At the time of writing the latest version of Universal 
// Interfaces was 3.3.2.  These definitions are not in UI 3.3.2,
// but will be in the next release version.
 
enum {
    gestaltMacOSCompatibilityBoxAttr = FOUR_CHAR_CODE('bbox'),
                /* Classic presence and features */
    gestaltMacOSCompatibilityBoxPresent = 0,                    
                /* True if running under the Classic */
    gestaltMacOSCompatibilityBoxHasSerial = 1,                  
                /* True if Classic serial support is implemented. */
    gestaltMacOSCompatibilityBoxless = 2                        
                /* True if we're Boxless (screen shared with 
                   Carbon/Cocoa) */
};
 
static Boolean RunningOnClassic(void)
{
    UInt32 response;
    
    return (Gestalt(gestaltMacOSCompatibilityBoxAttr, 
                    (SInt32 *) &response) == noErr)
                && ((response & 
                    (1 << gestaltMacOSCompatibilityBoxPresent))
                    != 0);
}

Listing 1. Detecting whether you're running in the Classic environment.

Q: My Carbon application does things on traditional Mac OS that just won't work on Mac OS X. How do I detect that I'm running on Mac OS X so that I can do things the right way on that platform?

A: DTS recommends that you test for specific functionality rather than for an entire platform. For example, if your application needs access to non-Carbon APIs on traditional Mac OS, we recommend that you access those APIs using GetSharedLibrary and FindSymbol; if the GetSharedLibrary call fails, you don't have access to the functionality, regardless of the platform.

On the other hand, we recognize that in some cases there is no convenient functional test, and only a platform test is possible. In such cases, your Carbon application can detect whether it is running on Mac OS X using Gestalt, as shown in Listing 2.

static Boolean RunningOnCarbonX(void)
{
    UInt32 response;
    
    return (Gestalt(gestaltSystemVersion, 
                    (SInt32 *) &response) == noErr)
                && (response >= 0x01000);
}

Listing 2. Detecting whether your Carbon application is running on Mac OS X.

[Jan 16 2001]


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