Add pure Python version for pointers

Author: gjbex

source-code/cython/Pointers/.gitignore

@@ -1 +1,2 @@
 pointers_cython.c
+pointers_pure.c

source-code/cython/Pointers/Makefile

@@ -1,11 +1,16 @@
 VERSION =  cpython-311-x86_64-linux-gnu
 CYTHON_LIB = pointers_cython.$(VERSION).so
+PURE_LIB = pointers_pure.$(VERSION).so
 
-all: $(CYTHON_LIB)
+all: $(CYTHON_LIB) $(PURE_LIB)
 
 $(CYTHON_LIB): pointers_cython.pyx
 	python setup.py build_ext --inplace
 
+$(PURE_LIB): pointers_pure.py
+	python setup.py build_ext --inplace
+
 clean:
 	python setup.py clean
-	$(RM) pointers_cython.c $(CYTHON_LIB)
+	$(RM) pointers_cython.c pointers_pure.c $(CYTHON_LIB) $(PURE_LIB)
+	$(RM) -r build

source-code/cython/Pointers/README.md

@@ -2,9 +2,13 @@
 Simple example of using pointers in Cython code.
 
 ## What is it?
-1. `pointers_cython.pyx`: code that computes a list of squares using a cdef
-    function that increments an integer value referred to by a pointer.
+1. `pointers_cython.pyx`: Cython code that computes a list of squares
+   using a cdef function that increments an integer value referred to
+   by a pointer.
+1. `pointers_pure.pyx`: pure Python code that computes a list of squares
+   using a cfunc function that increments an integer value referred to by
+   a pointer.
 1. `setup.py`: Python build script.
 1. `Makefile`: make file to build the extension.
-1. `squares.py`: script to load the compiled module, and compute the
-    squares of the first few positive integers.
+1. `squares.py`: script to load one of the compiled module, and compute
+   the squares of the first few positive integers.

source-code/cython/Pointers/pointers_pure.py

@@ -0,0 +1,14 @@
+import cython
+
+
+def squares(n: cython.int):
+    sqrs: list = []
+    i: cython.int = 0
+    while i < n:
+        sqrs.append(i**2)
+        incr(cython.address(i))
+    return sqrs
+
+@cython.cfunc
+def incr(i: cython.p_int):
+    i[0] += 1

source-code/cython/Pointers/setup.py

@@ -4,6 +4,6 @@
 from Cython.Build import cythonize
 
 setup(
-    ext_modules=cythonize('pointers_cython.pyx',
+    ext_modules=cythonize(['pointers_cython.pyx', 'pointers_pure.py'],
                           language_level='3str')
 )

source-code/cython/Pointers/squares.py

@@ -1,6 +1,18 @@
 #!/usr/bin/env python
 
-import pointers_cython as pointers
 
+import argparse
 
-print(pointers.squares(5))
+arg_parser = argparse.ArgumentParser(description='create a list of squares')
+arg_parser.add_argument('--n', type=int, default=5,
+                        help='number of squares to create')
+arg_parser.add_argument('module', choices=['pure_python', 'cython'],
+                        help='module to use for creating squares')
+options = arg_parser.parse_args()
+
+if options.module == 'pure_python':
+    import pointers_pure as pointers
+elif options.module == 'cython':
+    import pointers_cython as pointers
+
+print(pointers.squares(options.n))