support for ancient Python versions (2.7.x)

CMakeLists.txt

@@ -17,8 +17,8 @@ if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
 endif()
 
 set(Python_ADDITIONAL_VERSIONS 3.4 3.5 3.6)
-find_package(PythonLibs 3 REQUIRED)
-find_package(PythonInterp 3 REQUIRED)
+find_package(PythonLibs REQUIRED)
+find_package(PythonInterp REQUIRED)
 
 string(TOUPPER "${CMAKE_BUILD_TYPE}" U_CMAKE_BUILD_TYPE)
 if (UNIX)

README.md

@@ -19,10 +19,10 @@ become an excessively large and unnecessary dependency.
 
 Think of this library as a tiny self-contained version of Boost.Python with
 everything stripped away that isn't relevant for binding generation. The whole
-codebase requires just over 2000 lines of code and only depends on Python and
-the C++ standard library. This compact implementation was possible thanks to
-some of the new C++11 language features (tuples, lambda functions and variadic
-templates), and by only targeting Python 3.x and higher.
+codebase requires less than 3000 lines of code and only depends on Python (2.7
+or 3.x) and the C++ standard library. This compact implementation was possible
+thanks to some of the new C++11 language features (tuples, lambda functions and
+variadic templates).
 
 ## Core features
 The following core C++ features can be mapped to Python

example/example1.py

-#!/usr/bin/env python3
+#!/usr/bin/env python
+from __future__ import print_function
 import sys
 sys.path.append('.')
 

example/example10.py

-#!/usr/bin/env python3
+#!/usr/bin/env python
+from __future__ import print_function
 import sys
 sys.path.append('.')
 

example/example11.py

-#!/usr/bin/env python3
+#!/usr/bin/env python
+from __future__ import print_function
 import sys, pydoc
 sys.path.append('.')
 

example/example2.py

-#!/usr/bin/env python3
+#!/usr/bin/env python
+from __future__ import print_function
 import sys, pydoc
 sys.path.append('.')
 

example/example3.py

-#!/usr/bin/env python3
+#!/usr/bin/env python
+from __future__ import print_function
 import sys
 sys.path.append('.')
 

example/example4.py

-#!/usr/bin/env python3
+#!/usr/bin/env python
+from __future__ import print_function
 import sys
 sys.path.append('.')
 

example/example5.py

-#!/usr/bin/env python3
+#!/usr/bin/env python
+from __future__ import print_function
 import sys
 sys.path.append('.')
 

example/example6.py

-#!/usr/bin/env python3
+#!/usr/bin/env python
+from __future__ import print_function
 import sys
 sys.path.append('.')
 

example/example7.py

-#!/usr/bin/env python3
+#!/usr/bin/env python
+from __future__ import print_function
 import sys
 sys.path.append('.')
 

example/example8.py

-#!/usr/bin/env python3
+#!/usr/bin/env python
+from __future__ import print_function
 import sys
 sys.path.append('.')
 

example/example9.py

-#!/usr/bin/env python3
+#!/usr/bin/env python
+from __future__ import print_function
 import sys
 sys.path.append('.')
 

include/pybind/cast.h

@@ -25,7 +25,7 @@ NAMESPACE_BEGIN(detail)
 #endif
 
 /** Linked list descriptor type for function signatures (produces smaller binaries
- * compared to a previous solution using std::string and operator +=) */
+    compared to a previous solution using std::string and operator +=) */
 class descr {
 public:
     struct entry {
@@ -241,18 +241,42 @@ protected:
         PYBIND_TYPE_CASTER(type, #type); \
     };
 
+#if PY_MAJOR_VERSION >= 3
+#define PyLong_AsUnsignedLongLong_Fixed PyLong_AsUnsignedLongLong
+#define PyLong_AsLongLong_Fixed PyLong_AsLongLong
+#else
+inline PY_LONG_LONG PyLong_AsLongLong_Fixed(PyObject *o) {
+    if (PyInt_Check(o))
+        return (PY_LONG_LONG) PyLong_AsLong(o);
+    else
+        return ::PyLong_AsLongLong(o);
+}
+
+inline unsigned PY_LONG_LONG PyLong_AsUnsignedLongLong_Fixed(PyObject *o) {
+    if (PyInt_Check(o))
+        return (unsigned PY_LONG_LONG) PyLong_AsUnsignedLong(o);
+    else
+        return ::PyLong_AsUnsignedLongLong(o);
+}
+#endif
+
 PYBIND_TYPE_CASTER_NUMBER(int8_t, long, PyLong_AsLong, PyLong_FromLong)
 PYBIND_TYPE_CASTER_NUMBER(uint8_t, unsigned long, PyLong_AsUnsignedLong, PyLong_FromUnsignedLong)
 PYBIND_TYPE_CASTER_NUMBER(int16_t, long, PyLong_AsLong, PyLong_FromLong)
 PYBIND_TYPE_CASTER_NUMBER(uint16_t, unsigned long, PyLong_AsUnsignedLong, PyLong_FromUnsignedLong)
 PYBIND_TYPE_CASTER_NUMBER(int32_t, long, PyLong_AsLong, PyLong_FromLong)
 PYBIND_TYPE_CASTER_NUMBER(uint32_t, unsigned long, PyLong_AsUnsignedLong, PyLong_FromUnsignedLong)
-PYBIND_TYPE_CASTER_NUMBER(int64_t, PY_LONG_LONG, PyLong_AsLongLong, PyLong_FromLongLong)
-PYBIND_TYPE_CASTER_NUMBER(uint64_t, unsigned PY_LONG_LONG, PyLong_AsUnsignedLongLong, PyLong_FromUnsignedLongLong)
+PYBIND_TYPE_CASTER_NUMBER(int64_t, PY_LONG_LONG, PyLong_AsLongLong_Fixed, PyLong_FromLongLong)
+PYBIND_TYPE_CASTER_NUMBER(uint64_t, unsigned PY_LONG_LONG, PyLong_AsUnsignedLongLong_Fixed, PyLong_FromUnsignedLongLong)
 
 #if defined(__APPLE__) // size_t/ssize_t are separate types on Mac OS X
+#if PY_MAJOR_VERSION >= 3
 PYBIND_TYPE_CASTER_NUMBER(ssize_t, Py_ssize_t, PyLong_AsSsize_t, PyLong_FromSsize_t)
 PYBIND_TYPE_CASTER_NUMBER(size_t, size_t, PyLong_AsSize_t, PyLong_FromSize_t)
+#else
+PYBIND_TYPE_CASTER_NUMBER(ssize_t, PY_LONG_LONG, PyLong_AsLongLong_Fixed, PyLong_FromLongLong)
+PYBIND_TYPE_CASTER_NUMBER(size_t, unsigned PY_LONG_LONG, PyLong_AsUnsignedLongLong_Fixed, PyLong_FromUnsignedLongLong)
+#endif
 #endif
 
 PYBIND_TYPE_CASTER_NUMBER(float, double, PyFloat_AsDouble, PyFloat_FromDouble)
@@ -286,7 +310,19 @@ public:
 template <> class type_caster<std::string> {
 public:
     bool load(PyObject *src, bool) {
+#if PY_MAJOR_VERSION >= 3
         const char *ptr = PyUnicode_AsUTF8(src);
+#else
+        const char *ptr = nullptr;
+        object temp;
+        if (PyString_Check(src)) {
+            ptr = PyString_AsString(src);
+        } else {
+            temp = object(PyUnicode_AsUTF8String(src), false);
+            if (temp.ptr() != nullptr)
+                ptr = PyString_AsString(temp.ptr());
+        }
+#endif
         if (!ptr) { PyErr_Clear(); return false; }
         value = std::string(ptr);
         return true;
@@ -301,13 +337,25 @@ public:
 template <> class type_caster<std::wstring> {
 public:
     bool load(PyObject *src, bool) {
+#if PY_MAJOR_VERSION >= 3
         const wchar_t *ptr = PyUnicode_AsWideCharString(src, nullptr);
+#else
+        object temp(PyUnicode_AsUTF16String(src), false);
+        if (temp.ptr() == nullptr)
+            return false;
+        const wchar_t *ptr = (wchar_t*) PyString_AsString(temp.ptr());
+#endif
+
         if (!ptr) { PyErr_Clear(); return false; }
         value = std::wstring(ptr);
         return true;
     }
     static PyObject *cast(const std::wstring &src, return_value_policy /* policy */, PyObject * /* parent */) {
+#if PY_MAJOR_VERSION >= 3
         return PyUnicode_FromWideChar(src.c_str(), src.length());
+#else
+        return PyUnicode_DecodeUTF16((const char *) src.c_str(), src.length() * 2, "strict", nullptr);
+#endif
     }
     PYBIND_TYPE_CASTER(std::wstring, "wstr");
 };
@@ -316,7 +364,14 @@ public:
 template <> class type_caster<char> {
 public:
     bool load(PyObject *src, bool) {
+#if PY_MAJOR_VERSION >= 3
         char *ptr = PyUnicode_AsUTF8(src);
+#else
+        temp = object(PyUnicode_AsLatin1String(src), false);
+        if (temp.ptr() == nullptr)
+            return false;
+        char *ptr = PyString_AsString(temp.ptr());
+#endif
         if (!ptr) { PyErr_Clear(); return false; }
         value = ptr;
         return true;
@@ -337,6 +392,9 @@ public:
     operator char() { return *value; }
 protected:
     char *value;
+#if PY_MAJOR_VERSION < 3
+    object temp;
+#endif
 };
 
 template <typename T1, typename T2> class type_caster<std::pair<T1, T2>> {

include/pybind/common.h

@@ -24,9 +24,6 @@
 #endif
 #endif
 
-#define PYTHON_PLUGIN(name) \
-    extern "C" PYTHON_EXPORT PyObject *PyInit_##name()
-
 #include <vector>
 #include <string>
 #include <stdexcept>
@@ -37,7 +34,7 @@
 #if defined(_MSC_VER)
 #define HAVE_ROUND
 #pragma warning(push)
-#pragma warning(disable: 4510 4610 4512)
+#pragma warning(disable: 4510 4610 4512 4005)
 #if _DEBUG
 #define _DEBUG_MARKER
 #undef _DEBUG
@@ -61,6 +58,14 @@
 #pragma warning(pop)
 #endif
 
+#if PY_MAJOR_VERSION >= 3
+#define PYTHON_PLUGIN(name) \
+    extern "C" PYTHON_EXPORT PyObject *PyInit_##name()
+#else
+#define PYTHON_PLUGIN(name) \
+    extern "C" PYTHON_EXPORT PyObject *init##name()
+#endif
+
 NAMESPACE_BEGIN(pybind)
 
 typedef Py_ssize_t ssize_t;

include/pybind/numpy.h

@@ -47,7 +47,11 @@ public:
         static API lookup() {
             PyObject *numpy = PyImport_ImportModule("numpy.core.multiarray");
             PyObject *capsule = numpy ? PyObject_GetAttrString(numpy, "_ARRAY_API") : nullptr;
+#if PY_MAJOR_VERSION >= 3
             void **api_ptr = (void **) (capsule ? PyCapsule_GetPointer(capsule, NULL) : nullptr);
+#else
+            void **api_ptr = (void **) (capsule ? PyCObject_AsVoidPtr(capsule) : nullptr);
+#endif
             Py_XDECREF(capsule);
             Py_XDECREF(numpy);
             if (api_ptr == nullptr)

include/pybind/operators.h

@@ -103,7 +103,11 @@ inline op_<op_##id, op_u, self_t, undefined_t> op(const self_t &) {
 PYBIND_BINARY_OPERATOR(sub,       rsub,         operator-,    l - r)
 PYBIND_BINARY_OPERATOR(add,       radd,         operator+,    l + r)
 PYBIND_BINARY_OPERATOR(mul,       rmul,         operator*,    l * r)
+#if PY_MAJOR_VERSION >= 3
 PYBIND_BINARY_OPERATOR(truediv,   rtruediv,     operator/,    l / r)
+#else
+PYBIND_BINARY_OPERATOR(div,       rdiv,         operator/,    l / r)
+#endif
 PYBIND_BINARY_OPERATOR(mod,       rmod,         operator%,    l % r)
 PYBIND_BINARY_OPERATOR(lshift,    rlshift,      operator<<,   l << r)
 PYBIND_BINARY_OPERATOR(rshift,    rrshift,      operator>>,   l >> r)

include/pybind/pytypes.h

@@ -213,10 +213,30 @@ class str : public object {
 public:
     PYBIND_OBJECT_DEFAULT(str, object, PyUnicode_Check)
     str(const char *s) : object(PyUnicode_FromString(s), false) { }
-    operator const char *() const { return PyUnicode_AsUTF8(m_ptr); }
+    operator const char *() const {
+#if PY_MAJOR_VERSION >= 3
+        return PyUnicode_AsUTF8(m_ptr);
+#else
+        m_temp = object(PyUnicode_AsUTF8String(m_ptr), false);
+        if (m_temp.ptr() == nullptr)
+            return nullptr;
+        return PyString_AsString(m_temp.ptr());
+#endif
+    }
+private:
+#if PY_MAJOR_VERSION < 3
+    mutable object m_temp;
+#endif
 };
 
-inline pybind::str handle::str() const { return pybind::str(PyObject_Str(m_ptr), false); }
+inline pybind::str handle::str() const {
+    PyObject *str = PyObject_Str(m_ptr);
+#if PY_MAJOR_VERSION < 3
+    PyObject *unicode = PyUnicode_FromEncodedObject(str, "utf-8", nullptr);
+    Py_XDECREF(str); str = unicode;
+#endif
+    return pybind::str(str, false);
+}
 
 class bool_ : public object {
 public:
@@ -252,7 +272,13 @@ public:
         m_ptr = PySlice_New(start.ptr(), stop.ptr(), step.ptr());
     }
     bool compute(ssize_t length, ssize_t *start, ssize_t *stop, ssize_t *step, ssize_t *slicelength) const {
-        return PySlice_GetIndicesEx(m_ptr, length, start, stop, step, slicelength) == 0;
+        return PySlice_GetIndicesEx(
+#if PY_MAJOR_VERSION >= 3
+                m_ptr,
+#else
+                (PySliceObject *) m_ptr,
+#endif
+                length, start, stop, step, slicelength) == 0;
     }
 };
 

include/pybind/stl.h

@@ -100,9 +100,10 @@ public:
     PYBIND_TYPE_CASTER(type, detail::descr("dict<") + key_conv::name() + detail::descr(", ") + value_conv::name() + detail::descr(">"));
 };
 
+NAMESPACE_END(detail)
+
 inline std::ostream &operator<<(std::ostream &os, const object &obj) { os << (const char *) obj.str(); return os; }
 
-NAMESPACE_END(detail)
 NAMESPACE_END(pybind)
 
 #if defined(_MSC_VER)