Merge pull request #2286 from gabrieldemarmiesse/compat_py2_py3

Made code examples in the docs compatible with python 2 and 3.

docs/src/tutorial/array.rst

@@ -25,7 +25,7 @@ Safe usage with memory views
     cdef array.array a = array.array('i', [1, 2, 3])
     cdef int[:] ca = a
 
-    print ca[0]
+    print(ca[0])
 
 NB: the import brings the regular Python array object into the namespace
 while the cimport adds functions accessible from Cython.
@@ -51,8 +51,8 @@ functions without overhead, so long as it is typed::
     cdef int no_overhead(int[:] ca):
         return ca[0]
 
-    print overhead(a)  # new memory view will be constructed, overhead
-    print no_overhead(ca)  # ca is already a memory view, so no overhead
+    print(overhead(a))  # new memory view will be constructed, overhead
+    print(no_overhead(ca))  # ca is already a memory view, so no overhead
 
 Zero-overhead, unsafe access to raw C pointer
 ---------------------------------------------
@@ -69,7 +69,7 @@ right type and signedness.
     cdef array.array a = array.array('i', [1, 2, 3])
 
     # access underlying pointer:
-    print a.data.as_ints[0]
+    print(a.data.as_ints[0])
 
     from libc.string cimport memset
     memset(a.data.as_voidptr, 0, len(a) * sizeof(int))

docs/src/tutorial/pure.rst

@@ -57,7 +57,7 @@ file to be of the declared type.  Thus if one has a file :file:`A.py`::
             self.b = b
 
         def foo(self, x):
-            print x + _helper(1.0)
+            print(x + _helper(1.0))
 
 and adds :file:`A.pxd`::
 
@@ -84,7 +84,7 @@ then Cython will compile the :file:`A.py` as if it had been written as follows::
             self.b = b
 
         cpdef foo(self, double x):
-            print x + _helper(1.0)
+            print(x + _helper(1.0))
 
 Notice how in order to provide the Python wrappers to the definitions
 in the :file:`.pxd`, that is, to be accessible from Python,
@@ -312,8 +312,8 @@ Further Cython functions and declarations
   ::
 
     cython.declare(n=cython.longlong)
-    print cython.sizeof(cython.longlong)
-    print cython.sizeof(n)
+    print(cython.sizeof(cython.longlong))
+    print(cython.sizeof(n))
 
 * ``struct`` can be used to create struct types.::
 

docs/src/userguide/extension_types.rst

@@ -14,6 +14,8 @@ statement, Cython also lets you create new built-in Python types, known as
 extension types. You define an extension type using the :keyword:`cdef` class
 statement.  Here's an example::
 
+    from __future__ import print_function
+
     cdef class Shrubbery:
 
         cdef int width, height
@@ -23,8 +25,8 @@ statement.  Here's an example::
             self.height = h
 
         def describe(self):
-            print "This shrubbery is", self.width, \
-                "by", self.height, "cubits."
+            print("This shrubbery is", self.width,
+                  "by", self.height, "cubits.")
 
 As you can see, a Cython extension type definition looks a lot like a Python
 class definition. Within it, you use the def statement to define methods that
@@ -164,13 +166,13 @@ Suppose I have a method :meth:`quest` which returns an object of type :class:`Sh
 To access it's width I could write::
 
     cdef Shrubbery sh = quest()
-    print sh.width
+    print(sh.width)
 
 which requires the use of a local variable and performs a type test on assignment.
 If you *know* the return value of :meth:`quest` will be of type :class:`Shrubbery`
 you can use a cast to write::
 
-    print (<Shrubbery>quest()).width
+    print( (<Shrubbery>quest()).width )
 
 This may be dangerous if :meth:`quest()` is not actually a :class:`Shrubbery`, as it
 will try to access width as a C struct member which may not exist. At the C level,
@@ -178,21 +180,17 @@ rather than raising an :class:`AttributeError`, either an nonsensical result wil
 returned (interpreting whatever data is at that address as an int) or a segfault
 may result from trying to access invalid memory. Instead, one can write::
 
-    print (<Shrubbery?>quest()).width
+    print( (<Shrubbery?>quest()).width )
 
 which performs a type check (possibly raising a :class:`TypeError`) before making the
 cast and allowing the code to proceed.
 
-To explicitly test the type of an object, use the :meth:`isinstance` method. By default,
-in Python, the :meth:`isinstance` method checks the :class:`__class__` attribute of the
-first argument to determine if it is of the required type. However, this is potentially
-unsafe as the :class:`__class__` attribute can be spoofed or changed, but the C structure
-of an extension type must be correct to access its :keyword:`cdef` attributes and call its :keyword:`cdef` methods. Cython detects if the second argument is a known extension
-type and does a type check instead, analogous to Pyrex's :meth:`typecheck`.
-The old behavior is always available by passing a tuple as the second parameter::
-
-    print isinstance(sh, Shrubbery)     # Check the type of sh
-    print isinstance(sh, (Shrubbery,))  # Check sh.__class__
+To explicitly test the type of an object, use the :meth:`isinstance` method.
+For known builtin or extension types, Cython translates these into a
+fast and safe type check that ignores changes to
+the object's ``__class__`` attribute etc., so that after a successful
+:meth:`isinstance` test, code can rely on the expected C structure of the
+extension type and its :keyword:`cdef` attributes and methods.
 
 .. _extension_types_and_none:
 
@@ -340,16 +338,16 @@ when it is deleted.::
     from cheesy import CheeseShop
 
     shop = CheeseShop()
-    print shop.cheese
+    print(shop.cheese)
 
     shop.cheese = "camembert"
-    print shop.cheese
+    print(shop.cheese)
 
     shop.cheese = "cheddar"
-    print shop.cheese
+    print(shop.cheese)
 
     del shop.cheese
-    print shop.cheese
+    print(shop.cheese)
 
 .. sourcecode:: text
 
@@ -419,21 +417,21 @@ compared to a :keyword:`cdef` method::
     cdef class Parrot:
 
         cdef void describe(self):
-            print "This parrot is resting."
+            print("This parrot is resting.")
 
     cdef class Norwegian(Parrot):
 
         cdef void describe(self):
             Parrot.describe(self)
-            print "Lovely plumage!"
+            print("Lovely plumage!")
 
 
     cdef Parrot p1, p2
     p1 = Parrot()
     p2 = Norwegian()
-    print "p1:"
+    print("p1:")
     p1.describe()
-    print "p2:"
+    print("p2:")
     p2.describe()
 
 .. sourcecode:: text
@@ -643,6 +641,8 @@ objects defined in the Python core or in a non-Cython extension module.
 Here is an example which will let you get at the C-level members of the
 built-in complex object.::
 
+    from __future__ import print_function
+
     cdef extern from "complexobject.h":
 
         struct Py_complex:
@@ -654,8 +654,8 @@ built-in complex object.::
 
     # A function which uses the above type
     def spam(complex c):
-        print "Real:", c.cval.real
-        print "Imag:", c.cval.imag
+        print("Real:", c.cval.real)
+        print("Imag:", c.cval.imag)
 
 .. note::
 

docs/src/userguide/external_C_code.rst

@@ -475,7 +475,7 @@ made available when you include :file:`modulename_api.h`.::
 
     cdef api void activate(Vehicle *v):
         if v.speed >= 88 and v.power >= 1.21:
-            print "Time travel achieved"
+            print("Time travel achieved")
 
 .. sourcecode:: c
 

docs/src/userguide/fusedtypes.rst

@@ -26,6 +26,7 @@ Quickstart
 
 ::
 
+    from __future__ import print_function
     cimport cython
 
     ctypedef fused char_or_float:
@@ -41,8 +42,8 @@ Quickstart
         cdef:
             cython.char a = 127
             cython.float b = 127
-        print 'char', plus_one(a)
-        print 'float', plus_one(b)
+        print('char', plus_one(a))
+        print('float', plus_one(b))
 
 This gives::
 
@@ -267,7 +268,7 @@ to figure out whether a specialization is part of another set of types
             long_pointer = &i
 
         if bunch_of_types in string_t:
-            print "s is a string!"
+            print("s is a string!")
 
 __signatures__
 ==============

docs/src/userguide/language_basics.rst

@@ -124,6 +124,8 @@ internally to store attributes.
 
 Here is a simple example::
 
+    from __future__ import print_function
+
     cdef class Shrubbery:
 
         cdef int width, height
@@ -133,8 +135,8 @@ Here is a simple example::
             self.height = h
 
         def describe(self):
-            print "This shrubbery is", self.width, \
-                "by", self.height, "cubits."
+            print("This shrubbery is", self.width,
+                  "by", self.height, "cubits.")
 
 You can read more about them in :ref:`extension-types`.
 
@@ -194,6 +196,8 @@ Grouping multiple C declarations
 If you have a series of declarations that all begin with :keyword:`cdef`, you
 can group them into a :keyword:`cdef` block like this::
 
+    from __future__ import print_function
+
     cdef:
         struct Spam:
             int tons
@@ -203,7 +207,7 @@ can group them into a :keyword:`cdef` block like this::
         Spam *p
 
         void f(Spam *s):
-            print s.tons, "Tons of spam"
+            print(s.tons, "Tons of spam")
 
 .. _cpdef:
 .. _cdef:
@@ -645,7 +649,6 @@ with ``<object>``, or a more specific builtin or extension type
 the object by one, i.e. the cast returns an owned reference.
 Here is an example::
 
-    from __future__ import print_function
     from cpython.ref cimport PyObject
     from libc.stdint cimport uintptr_t
 
@@ -985,9 +988,11 @@ expression must evaluate to a Python value of type ``int``, ``long``,
 
 ::
 
+    from __future__ import print_function
+
     cdef int a1[ArraySize]
     cdef int a2[OtherArraySize]
-    print "I like", FavouriteFood
+    print("I like", FavouriteFood)
 
 Conditional Statements
 ----------------------

docs/src/userguide/limitations.rst

@@ -60,4 +60,4 @@ Identity vs. equality for inferred literals
     if some_runtime_expression:
         b = a        # creates a new Python float object
         c = a        # creates a new Python float object
-    print b is c     # most likely not the same object
+    print(b is c)     # most likely not the same object

docs/src/userguide/sharing_declarations.rst

@@ -101,7 +101,7 @@ uses it.
     def serve():
         cdef spamdish d
         prepare(&d)
-        print "%d oz spam, filler no. %d" % (d.oz_of_spam, d.filler)
+        print("%d oz spam, filler no. %d" % (d.oz_of_spam, d.filler))
 
 It is important to understand that the :keyword:`cimport` statement can only
 be used to import C data types, C functions and variables, and extension
@@ -184,11 +184,13 @@ example:
 
 :file:`spammery.pyx`::
 
+    from __future__ import print_function
+
     from volume cimport cube
 
     def menu(description, size):
-        print description, ":", cube(size), \
-            "cubic metres of spam"
+        print(description, ":", cube(size),
+              "cubic metres of spam")
 
     menu("Entree", 1)
     menu("Main course", 3)
@@ -243,7 +245,7 @@ and another module which uses it:
 
     cdef Shrubbing.Shrubbery sh
     sh = Shrubbing.standard_shrubbery()
-    print "Shrubbery size is %d x %d" % (sh.width, sh.length)
+    print("Shrubbery size is %d x %d" % (sh.width, sh.length))
 
 One would then need to compile both of these modules, e.g. using
 

docs/src/userguide/wrapping_CPlusPlus.rst

@@ -428,7 +428,7 @@ Cython uses a bracket syntax for templating. A simple example for wrapping C++ v
 
     cdef vector[int].iterator it = v.begin()
     while it != v.end():
-        print deref(it)
+        print(deref(it))
         inc(it)
 
     del v
@@ -447,8 +447,8 @@ the template parameter list following the function name::
     cdef extern from "<algorithm>" namespace "std":
         T max[T](T a, T b)
 
-    print max[long](3, 4)
-    print max(1.5, 2.5)  # simple template argument deduction
+    print(max[long](3, 4))
+    print(max(1.5, 2.5))  # simple template argument deduction
 
 
 Standard library
@@ -467,7 +467,7 @@ For example::
     for i in range(10):
         vect.push_back(i)
     for i in range(10):
-        print vect[i]
+        print(vect[i])
 
 The pxd files in ``/Cython/Includes/libcpp`` also work as good examples on
 how to declare C++ classes.