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9.2 Memory Interface

The following function sets, modeled after the ANSI C standard, but specifying behavior when requesting zero bytes, are available for allocating and releasing memory from the Python heap:

void* `PyMem_Malloc`( | size_t n)

  Allocates n bytes and returns a pointer of type `void*` to the allocated memory, or `NULL` if the request fails. Requesting zero bytes returns a distinct non-`NULL` pointer if possible, as if `PyMem_Malloc(1)` had been called instead. The memory will not have been initialized in any way.

void* `PyMem_Realloc`( | void *p, size_t n)

  Resizes the memory block pointed to by p to n bytes. The contents will be unchanged to the minimum of the old and the new sizes. If p is `NULL`, the call is equivalent to `PyMem_Malloc(n)`; else if n is equal to zero, the memory block is resized but is not freed, and the returned pointer is non-`NULL`. Unless p is `NULL`, it must have been returned by a previous call to `PyMem_Malloc()` or `PyMem_Realloc()`. If the request fails, `PyMem_Realloc()` returns `NULL` and p remains a valid pointer to the previous memory area.

void `PyMem_Free`( | void *p)

  Frees the memory block pointed to by p, which must have been returned by a previous call to `PyMem_Malloc()` or `PyMem_Realloc()`. Otherwise, or if `PyMem_Free(p)` has been called before, undefined behavior occurs. If p is `NULL`, no operation is performed.

The following type-oriented macros are provided for convenience. Note that TYPE refers to any C type.

TYPE* `PyMem_New`( | TYPE, size_t n)

  Same as `PyMem_Malloc()`, but allocates `(n * sizeof(TYPE))` bytes of memory. Returns a pointer cast to `TYPE*`. The memory will not have been initialized in any way.

TYPE* `PyMem_Resize`( | void *p, TYPE, size_t n)

  Same as `PyMem_Realloc()`, but the memory block is resized to `(n * sizeof(TYPE))` bytes. Returns a pointer cast to `TYPE*`. On return, p will be a pointer to the new memory area, or `NULL` in the event of failure.

void `PyMem_Del`( | void *p)

  Same as `PyMem_Free()`.

In addition, the following macro sets are provided for calling the Python memory allocator directly, without involving the C API functions listed above. However, note that their use does not preserve binary compatibility across Python versions and is therefore deprecated in extension modules.

`PyMem_MALLOC()`, `PyMem_REALLOC()`, `PyMem_FREE()`.

`PyMem_NEW()`, `PyMem_RESIZE()`, `PyMem_DEL()`.