Class: CFAllocatorContext
Overview
A structure that defines the context or operating environment for an allocator (CFAllocator) object. Every Core Foundation allocator object must have a context defined for it.
Instance Attribute Summary (collapse)
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- allocate
A prototype for a function callback that allocates memory of a requested size.
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- copyDescription
A prototype for a function callback that provides a description of the data pointed to by the info field.
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- deallocate
A prototype for a function callback that deallocates a given block of memory.
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- preferredSize
A prototype for a function callback that determines whether there is enough free memory to satisfy a request.
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- reallocate
A prototype for a function callback that reallocates memory of a requested size for an existing block of memory.
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- release
A prototype for a function callback that releases the data pointed to by the info field.
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- retain
A prototype for a function callback that retains the data pointed to by the info field.
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- version
An integer of type CFIndex.
Method Summary
Methods inherited from Boxed
Methods inherited from NSObject
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Constructor Details
This class inherits a constructor from NSObject
Dynamic Method Handling
This class handles dynamic methods through the method_missing method in the class NSObject
Instance Attribute Details
- (CFAllocatorAllocateCallBack) allocate
A prototype for a function callback that allocates memory of a requested size. In implementing this function, allocate a block of memory of at least size bytes and return a pointer to the start of the block. The hint argument is a bitfield that you should currently not use (that is, assign 0). The size parameter should always be greater than 0. If it is not, or if problems in allocation occur, return NULL. This function pointer may not be assigned NULL.
- (CFAllocatorCopyDescriptionCallBack) copyDescription
A prototype for a function callback that provides a description of the data pointed to by the info field. In implementing this function, return a reference to a CFString object that describes your allocator, particularly some characteristics of your program-defined data. You may set this function pointer to NULL, in which case Core Foundation will provide a rudimentary description.
- (CFAllocatorDeallocateCallBack) deallocate
A prototype for a function callback that deallocates a given block of memory. In implementing this function, make the block of memory pointed to by ptr available for subsequent reuse by the allocator but unavailable for continued use by the program. The ptr parameter cannot be NULL and if the ptr parameter is not a block of memory that has been previously allocated by the allocator, the results are undefined; abnormal program termination can occur. You can set this callback to NULL, in which case the CFAllocatorDeallocate function has no effect.
- (CFAllocatorPreferredSizeCallBack) preferredSize
A prototype for a function callback that determines whether there is enough free memory to satisfy a request. In implementing this function, return the actual size the allocator is likely to allocate given a request for a block of memory of size size. The hint argument is a bitfield that you should currently not use.
- (CFAllocatorReallocateCallBack) reallocate
A prototype for a function callback that reallocates memory of a requested size for an existing block of memory. In implementing this function, change the size of the block of memory pointed to by ptr to the size specified by newsize and return the pointer to the larger block of memory. Return NULL on any reallocation failure, leaving the old block of memory untouched. Also return NULL immediately if any of the following conditions apply:The ptr parameter is NULL. The newsize parameter is not greater than 0. Leave the contents of the old block of memory unchanged up to the lesser of the new or old sizes. If the ptr parameter is not a block of memory that has been previously allocated by the allocator, the results are undefined; abnormal program termination can occur. The hint argument is a bitfield that you should currently not use (that is, assign 0). If you set this callback to NULL the CFAllocatorReallocate function returns NULL in most cases when it attempts to use this allocator.
- (CFAllocatorReleaseCallBack) release
A prototype for a function callback that releases the data pointed to by the info field. In implementing this function, release (or free) the data you have defined for the allocator context. You may set this function pointer to NULL, but doing so might result in memory leaks.
- (CFAllocatorRetainCallBack) retain
A prototype for a function callback that retains the data pointed to by the info field. In implementing this function, retain the data you have defined for the allocator context in this field. (This might make sense only if the data is a Core Foundation object.) You may set this function pointer to NULL.
- (CFIndex) version
An integer of type CFIndex. Assign the version number of the allocator. Currently the only valid value is 0.