2001-03-03 10:00:31 +00:00
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<title>NSFunctions</title>
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<a href ="Base.html">[Up]</a>
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<h1>NSFunctions</h1>
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<h3>Authors </h3>
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<dl>
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<dt><a href ="http://www.gnustep.org/developers/whoiswho.html">Richard Frith-Macdonald</a>
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<dd>
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2001-04-19 17:28:22 +00:00
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<dt><a href ="http://www.gnustep.org/developers/whoiswho.html">Nicola Pero</a>
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<dd>
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2001-03-03 10:00:31 +00:00
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</dl>
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<p>Version: $Revision$</p>
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<p>Date: $Date$</p>
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2001-04-10 03:27:01 +00:00
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<h2><a name ="cont-0">Functions</a></h2>
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2001-04-19 17:28:22 +00:00
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<h3><a name ="cont-1">Thread Function</a></h3>
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2001-04-12 12:25:23 +00:00
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<h2><a name ="function-0">GSCurrentThread</a></h2>
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<p><b>Declared in: </b> Foundation/NSThread.h</p>
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<b>Prototype: </b> NSThread* GSCurrentThread()<br>
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<p>
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This function is a GNUstep extension. It pretty much
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duplicates the functionality of [NSThread +currentThread]
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but is more efficient and is used internally throughout
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GNUstep.
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</p>
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<p>
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Returns the current thread. Could perhaps return <code>nil</code>
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if executing a thread that was started outside the GNUstep
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environment and not registered (this should not happen in a
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well-coded application).
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</p>
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<hr>
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<h2><a name ="function-1">GSRegisterCurrentThread</a></h2>
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<p><b>Declared in: </b> Foundation/NSThread.h</p>
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<b>Prototype: </b> BOOL GSRegisterCurrentThread()<br>
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<p>
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2001-04-19 17:28:22 +00:00
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This function is provided to let threads started by some other
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2001-04-12 12:25:23 +00:00
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software library register themselves to be used with the
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GNUstep system. All such threads should call this function
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before attempting to use any GNUstep objects.
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</p>
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<p>
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Returns <code>YES</code> if the thread can be registered,
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<code>NO</code> if it is already registered.
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</p>
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<p>
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Sends out a <code>NSWillBecomeMultiThreadedNotification</code>
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if the process was not already multithreaded.
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</p>
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<hr>
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<h2><a name ="function-2">GSUnregisterCurrentThread</a></h2>
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<p><b>Declared in: </b> Foundation/NSThread.h</p>
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<b>Prototype: </b> void GSUnregisterCurrentThread()<br>
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<p>
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2001-04-19 17:28:22 +00:00
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This function is provided to let threads started by some other
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2001-04-12 12:25:23 +00:00
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software library unregister themselves from the GNUstep threading
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system.
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</p>
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<p>
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Calling this function causes a
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<code>NSThreadWillExitNotification</code>
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to be sent out, and destroys the GNUstep NSThread object
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associated with the thread.
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</p>
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<hr>
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2001-04-19 17:28:22 +00:00
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<h3><a name ="cont-2">Debugging Functions - Counting Instances of Classes</a></h3>
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<h2><a name ="function-3">GSDebugAllocationActive</a></h2>
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<p><b>Declared in: </b> Foundation/NSDebug.h</p>
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<b>Prototype: </b> BOOL GSDebugAllocationActive(BOOL active)<br>
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<p>
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This function is a GNUstep extension. It activates or
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deactivates object allocation debugging. Returns the
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previous state. You should call this function to activate
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allocation debugging before using any of the functions
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described in this section. Object allocation debugging
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should not affect performance too much, and is very useful
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as it allows you to monitor how many objects of each class
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your application has allocated. See below for a detailed
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description of the info you can get, and why it is useful.
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</p>
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<hr>
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<h2><a name ="function-4">GSDebugAllocationCount</a></h2>
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<p><b>Declared in: </b> Foundation/NSDebug.h</p>
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<b>Prototype: </b> int GSDebugAllocationCount(Class c)<br>
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<p>
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This function is a GNUstep extension. Returns the number
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of instances of the specified class which are currently
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allocated. This number is very important to detect memory
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leaks. If you notice that this number is constantly
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increasing without apparent reason, it is very likely a
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memory leak - you need to check that you are correctly
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releasing objects of this class, otherwise when your
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application runs for a long time, it will eventually
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allocate so many objects as to eat up all your system's
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memory ...
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</p>
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<p>
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This function, like the ones below, returns the number of
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objects allocated/released from the time when
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GSDebugAllocationActive was first called. A negative
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number means that in total, there are less objects of this
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class allocated now than there were when you called
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GSDebugAllocationActive; a positive one means there are
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more.
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</p>
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<hr>
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<h2><a name ="function-5">GSDebugAllocationPeak</a></h2>
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<p><b>Declared in: </b> Foundation/NSDebug.h</p>
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<b>Prototype: </b> int GSDebugAllocationPeak(Class c)<br>
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<p>
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This function is a GNUstep extension. Returns the peak
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number of instances of the specified class which have been
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concurrently allocated. If this number is very high, it
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means at some point in time you had a situation with a
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huge number of objects of this class allocated - this is
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an indicator that probably at some point in time your
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application was using a lot of memory - so you might want
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to investigate whether you can prevent this problem by
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inserting autorelease pools in your application's
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processing loops.
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</p>
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<hr>
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<h2><a name ="function-6">GSDebugAllocationTotal</a></h2>
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<p><b>Declared in: </b> Foundation/NSDebug.h</p>
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<b>Prototype: </b> int GSDebugAllocationTotal(Class c)<br>
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<p>
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This function is a GNUstep extension. Returns the total
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number of instances of the specified class which have been
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allocated - basically the number of times you have
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allocated an object of this class. If this number is very
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high, it means you are creating a lot of objects of this
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class; even if you are releasing them correctly, you must
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not forget that allocating and deallocating objects is
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usually one of the slowest things you can do, so you might
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want to consider whether you can reduce the number of
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allocations and deallocations that you are doing - for
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example, by recycling objects of this class, uniquing
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them, and/or using some sort of flyweight pattern. It
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might also be possible that you are unnecessarily creating
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too many objects of this class. Well - of course some times
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there is nothing you can do about it.
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</p>
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<hr>
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<h2><a name ="function-7">GSDebugAllocationClassList</a></h2>
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<p><b>Declared in: </b> Foundation/NSDebug.h</p>
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<b>Prototype: </b> Class* GSDebugAllocationClassList()<br>
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<p>
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This function is a GNUstep extension. Returns a NULL
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terminated array listing all the classes for which
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statistical information has been collected. Usually, you
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call this function, and then loop on all the classes returned,
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and for each one you get current, peak and total count by
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using GSDebugAllocationCount, GSDebugAllocationPeak and
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GSDebugAllocationTotal.
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</p>
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<hr>
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<h2><a name ="function-8">GSDebugAllocationList</a></h2>
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<p><b>Declared in: </b> Foundation/NSDebug.h</p>
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<b>Prototype: </b> const char* GSDebugAllocationList()<br>
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<p>
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This function is a GNUstep extension. Returns a newline
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separated list of the classes which have instances
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allocated, and the instance counts. If the 'changeFlag'
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argument is YES then the list gives the number of
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instances allocated/deallocated since the function was
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last called. This function only returns the current count
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of instances (not the peak or total count), but its output
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is ready to be displayed or logged.
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</p>
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<hr>
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<h2><a name ="function-9">GSDebugAllocationListAll</a></h2>
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<p><b>Declared in: </b> Foundation/NSDebug.h</p>
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<b>Prototype: </b> const char* GSDebugAllocationListAll()<br>
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<p>
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This function is a GNUstep extension. Returns a newline
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separated list of the classes which have had instances
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allocated at any point, and the total count of the number
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of instances allocated for each class. The difference with
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GSDebugAllocationList is that this function returns also
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classes which have no objects allocated at the moment, but
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which had in the past.
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</p>
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<hr>
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<h3><a name ="cont-3">Debugging Functions - Tracking Instances of Classes</a></h3>
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<h2><a name ="function-10">GSDebugAllocationActiveRecordingObjects</a></h2>
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<p><b>Declared in: </b> Foundation/NSDebug.h</p>
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<b>Prototype: </b> void GSDebugAllocationActiveRecordingObjects()<br>
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<p>
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This function is a GNUstep extension. It activates
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tracking all allocated instances of the specified class
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(passed as argument). This tracking can slow your
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application down, so you should use it only when you are
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into serious debugging. Usually, you will monitor your
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application by using the functions GSDebugAllocationList
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and similia (see above), which do not slow things down
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much and return the number of allocated instances; when
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(if) by studying the reports generated by these functions
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you have found a leak of objects of a certain class, and
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if you can't figure out how to fix it by looking at the
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code, you can use this function to start tracking
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allocated instances of that class, and the following one
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can sometime allow you to list the leaked objects directly.
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</p>
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<hr>
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<h2><a name ="function-11">GSDebugAllocationListRecordedObjects</a></h2>
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<p><b>Declared in: </b> Foundation/NSDebug.h</p>
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<b>Prototype: </b> NSArray * GSDebugAllocationListRecordedObjects(Class c)<br>
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<p>
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This function is a GNUstep extension. Returns an array
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containing all the allocated objects of a certain class
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which have been recorded (to start the recording, you need
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to invoke GSDebugAllocationActiveRecordedObjects).
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Presumably, you will immediately call -description on them
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to find out the objects you are leaking. The objects are
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returned in an array, so until the array is autoreleased,
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the objects are not released.
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</p>
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<hr>
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<h2><a name ="cont-4">Types</a></h2>
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2001-04-10 03:27:01 +00:00
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<h3><a name ="NSRange">NSRange</a></h3>
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<p><b>Declared in: </b> Foundation/NSRange.h</p>
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<b>typedef </b>
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struct { unsigned long location; unsigned long length; }
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NSRange<br>
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<p>
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The NSRange type is used to specify ranges of locations,
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typically items in an array, characters in a string, and bytes
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in a data object.
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</p>
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<p>
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As 'boundary' or 'fencepost' errors are a particularly common
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problem in programming, it is important that you understand
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how an NSRange works.
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</p>
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<p>
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An NSRange consists of a location and a length. The points
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that are considered to lie in a range are the integers from
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the location to the location plus the length, so the number
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of points in a range is the length of the range plus one.<br>
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However, if you consider these points like the marks on a
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ruler, you can only store information <strong>between</strong>
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points. So the number of items that can be stored in a range
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is the length of the range.
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</p>
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<hr>
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2001-03-03 10:00:31 +00:00
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</body>
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</html>
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