docs: Pythonise documentation on Memory Allocation (memory_allocation.rst) (GH-4316)

1 files changed, 24 insertions, 0 deletions

diff --git a/docs/examples/tutorial/memory_allocation/malloc.py b/docs/examples/tutorial/memory_allocation/malloc.py
new file mode 100644
index 000000000..fb7e82236
--- /dev/null
+++ b/docs/examples/tutorial/memory_allocation/malloc.py
@@ -0,0 +1,24 @@
+import random
+from cython.cimports.libc.stdlib import malloc, free
+
+def random_noise(number: cython.int = 1):
+    i: cython.int
+    # allocate number * sizeof(double) bytes of memory
+    my_array: cython.p_double = cython.cast(cython.p_double, malloc(
+        number * cython.sizeof(cython.double)))
+    if not my_array:
+        raise MemoryError()
+
+    try:
+        ran = random.normalvariate
+        for i in range(number):
+            my_array[i] = ran(0, 1)
+
+        # ... let's just assume we do some more heavy C calculations here to make up
+        # for the work that it takes to pack the C double values into Python float
+        # objects below, right after throwing away the existing objects above.
+
+        return [x for x in my_array[:number]]
+    finally:
+        # return the previously allocated memory to the system
+        free(my_array)