[Boost-users] Compile error OSX Callback problem for FSEventsCallback

Subject: [Boost-users] Compile error OSX Callback problem for FSEventsCallback
From: Bill McLean (bill_at_[hidden])
Date: 2009-01-03 16:59:12

I'm trying to code up a FSEvent callback using a member function. I may be
suffering from a case of the post holiday stupids :)

 

I am using both the boost::bind and boost::function libraries. I have the
following declaration for declaring the signature of the FSEventCallback:

 

                typedef boost::function<void (

                    ConstFSEventStreamRef streamRef, // _1

                    void *clientCallBackInfo, // _2

                    size_t numEvents, // _3

                    void *eventPaths, // _4

                    const FSEventStreamEventFlags eventFlags[], // _5

                    const FSEventStreamEventId eventIds[] // _6

                )> FSEventCallbackT;

 

The above typedef has been derived from the OSX FSEvent API definition for
the FSEventStreamCallback:

 

                typedef void ( *FSEventStreamCallback)( 

                    ConstFSEventStreamRef streamRef, 

                    void *clientCallBackInfo, 

                    size_t numEvents, 

                    void *eventPaths, 

                    const FSEventStreamEventFlags eventFlags[], 

                    const FSEventStreamEventId eventIds[]

                );

 

The skeleton of the struct that has the member function that is to be the
call back is defined as:

 

                struct osx::detail {

                    // Callback type definition

 

                    static const CFAbsoluteTime LATENCY = 2.0;

                    static const unsigned BUF_SIZE = 32768;

                    CFStringRef pathToWatch;

                    CFArrayRef pathsToWatch; 

                    FSEventStreamRef streamRef;

                    void *callbackInfo;

                    CFRunLoopRef mainLoop;

                    boost::mutex event_mutex;

                    typedef boost::mutex::scoped_lock lock_type;

                    FSEventCallbackT callBack;

                    // public methods

 

                    detail(

                        const boost::filesystem::path& base_path

                    );

 

                    ~detail() {

                        stop();

                    }

 

                    void stop();

 

 

                    void FSEventTriggered(

                        ConstFSEventStreamRef streamRef, // _1

                        void *clientCallBackInfo, // _2

                        size_t numEvents, // _3

                        void *eventPaths, // _4

                        const FSEventStreamEventFlags eventFlags[], // _5

                        const FSEventStreamEventId eventIds[] // _6

                    );

 

                    item get_item();

                };

 

 

In the constructor I get a single compile error in the call to
FSEventStreamCreate:

 

                osx::detail::detail(

                    const boost::filesystem::path& base_path

                ) :

                    base_path(base_path),

                    stopped(false),

                    pathToWatch(CFStringCreateWithCString(NULL,base_pa
th.string().c_str(), kCFStringEncodingUTF8)),

                    pathsToWatch(CFArrayCreate(NULL, (const void **)
&pathToWatch, 1, NULL))

                {

                    callBack = boost::bind(&fsmon ::
osx::detail::FSEventTriggered, this, _1, _2, _3, _4, _5, _6);

                    streamRef = FSEventStreamCreate(NULL,

                        &callBack,

                        callbackInfo,

                        pathsToWatch,

                        kFSEventStreamEventIdSinceNow,

                        LATENCY,

                        kFSEventStreamCreateFlagNone

                    );

                    ...

                }

 

 
/Users/bill/ardev/CurrentDev/InternalLibs/fsmon/osxExample.cpp:111: error:
cannot convert 'FSEventCallbackT*' to 'void (*)(const __FSEventStream*,
void*, size_t, void*, const FSEventStreamEventFlags*, const
FSEventStreamEventId*)' for argument '2' to '__FSEventStream*
FSEventStreamCreate(const __CFAllocator*, void (*)(const __FSEventStream*,
void*, size_t, void*, const FSEventStreamEventFlags*, const
FSEventStreamEventId*), FSEventStreamContext*, const __CFArray*,
FSEventStreamEventId, CFTimeInterval, FSEventStreamCreateFlags)'

                

                The typdef for FSEventCallbackT should be the same as the
void (*)(const __FSEventStream*, void*, size_t, void*, const
FSEventStreamEventFlags*, const FSEventStreamEventId*).

 

I do not see what I am doing incorrectly.  Thanks in advance.

 

Bill