added exec functions

docs/advanced.rst

@@ -1611,3 +1611,33 @@ work, it is important that all lines are indented consistently, i.e.:
 
 
 .. [#f4] http://www.sphinx-doc.org
 .. [#f4] http://www.sphinx-doc.org
 .. [#f5] http://github.com/pybind/python_example
 .. [#f5] http://github.com/pybind/python_example
+
+Calling Python from C++
+=======================
+
+Pybind11 also allows to call python code from C++. Note that this code assumes, that the intepreter is already initialized.
+
+.. code-block:: cpp
+
+	// get the main module, so we can access and declare stuff
+	py::module main_module = py::module::import("__main__");
+	
+	//get the main namespace, so I can declare variables
+	py::object main_namespace = main_module.attr("__dict__");
+
+    //now execute code
+	py::exec(
+		"print('Hello World1!')\n"
+		"print('Other Data');",
+        main_namespace);	    
+
+    //execute a single statement
+    py::exec_statement("x=42", main_namespace);
+
+    //ok, now I want to get the result of a statement, we'll use x in this example
+    py::object res = py::eval("x");
+    std:cout <<  "Yielded: " << res.cast<int>() << std::endl;
+    
+    //or we can execute a file within the same content
+    py::exec_file("my_script.py", main_namespace);
+    

docs/reference.rst

@@ -244,3 +244,26 @@ Passing extra arguments to the def function
 .. function:: name::name(const char *value)
 .. function:: name::name(const char *value)
 
 
     Used to specify the function name
     Used to specify the function name
+    
+Calling Python from C++
+=======================
+
+.. function:: eval(str string, object global = object(), object local = object())
+     
+     Evaluate a statement, i.e. one that does not yield None. 
+     The return value the result of the expression. It throws pybind11::error_already_set if the commands are invalid.
+     
+.. function:: exec(str string, object global = object(), object local = object())
+
+     Execute a set of statements. The return value the result of the code. It throws pybind11::error_already_set if the commands are invalid.
+     
+.. function:: exec_statement(str string, object global = object(), object local = object())
+    
+     Execute a single statement. The return value the result of the code. It throws pybind11::error_already_set if the commands are invalid.
+     
+.. function:: exec_file(str filename, object global = object(), object local = object())     
+     
+     Execute a file. The function exec_file will throw std::invalid_argument if the file cannot be opened.
+     The return value the result of the code. It throws pybind11::error_already_set if the commands are invalid and
+     std::invalid_argument if the file cannot be opened.
+

example/CMakeLists.txt

@@ -24,6 +24,7 @@ set(PYBIND11_EXAMPLES
   example15.cpp
   example15.cpp
   example16.cpp
   example16.cpp
   example17.cpp
   example17.cpp
+  example18.cpp
   issues.cpp
   issues.cpp
 )
 )
 
 
@@ -66,3 +67,4 @@ foreach(VALUE ${PYBIND11_EXAMPLES})
   string(REGEX REPLACE "^(.+).cpp$" "\\1" EXAMPLE_NAME "${VALUE}")
   string(REGEX REPLACE "^(.+).cpp$" "\\1" EXAMPLE_NAME "${VALUE}")
   add_test(NAME ${EXAMPLE_NAME} COMMAND ${RUN_TEST} ${EXAMPLE_NAME})
   add_test(NAME ${EXAMPLE_NAME} COMMAND ${RUN_TEST} ${EXAMPLE_NAME})
 endforeach()
 endforeach()
+

example/example.cpp

@@ -26,6 +26,7 @@ void init_ex14(py::module &);
 void init_ex15(py::module &);
 void init_ex15(py::module &);
 void init_ex16(py::module &);
 void init_ex16(py::module &);
 void init_ex17(py::module &);
 void init_ex17(py::module &);
+void init_ex18(py::module &);
 void init_issues(py::module &);
 void init_issues(py::module &);
 
 
 #if defined(PYBIND11_TEST_EIGEN)
 #if defined(PYBIND11_TEST_EIGEN)
@@ -52,6 +53,7 @@ PYBIND11_PLUGIN(example) {
     init_ex15(m);
     init_ex15(m);
     init_ex16(m);
     init_ex16(m);
     init_ex17(m);
     init_ex17(m);
+    init_ex18(m);
     init_issues(m);
     init_issues(m);
 
 
     #if defined(PYBIND11_TEST_EIGEN)
     #if defined(PYBIND11_TEST_EIGEN)

example/example18.cpp

+/*
+    example/example18.cpp -- Usage of exec, eval etc.
+
+    Copyright (c) 2016 Klemens D. Morgenstern
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+
+#include <pybind11/exec.h>
+#include "example.h"
+
+void example18() {
+    py::module main_module = py::module::import("__main__");
+    py::object main_namespace = main_module.attr("__dict__");
+
+    bool executed = false;
+
+    main_module.def("call_test", [&]()-> int {executed = true; return 42;});
+
+    cout << "exec test" << endl;
+
+    py::exec(
+            "print('Hello World!');\n"
+            "x = call_test();",
+                          main_namespace);
+
+    if (executed)
+        cout << "exec passed" << endl;
+    else {
+        cout << "exec failed" << endl;
+    }
+
+    cout << "eval test" << endl;
+
+    py::object val = py::eval("x", main_namespace);
+
+    if (val.cast<int>() == 42)
+        cout << "eval passed" << endl;
+    else {
+        cout << "eval failed" << endl;
+    }
+
+
+    executed = false;
+    cout << "exec_statement test" << endl;
+
+    py::exec_statement("y = call_test();", main_namespace);
+
+
+    if (executed)
+        cout << "exec_statement passed" << endl;
+    else {
+        cout << "exec_statement failed" << endl;
+    }
+
+    cout << "exec_file test" << endl;
+
+    int val_out;
+    main_module.def("call_test2", [&](int value) {val_out = value;});
+
+
+    py::exec_file("example18_call.py", main_namespace);
+
+    if (val_out == 42)
+        cout << "exec_file passed" << endl;
+    else {
+        cout << "exec_file failed" << endl;
+    }
+
+    executed = false;
+    cout << "exec failure test" << endl;
+    try {
+    	py::exec("non-sense code ...");
+    }
+    catch (py::error_already_set & err) {
+    	executed = true;
+    }
+    if (executed)
+        cout << "exec failure test passed" << endl;
+    else {
+        cout << "exec failure test failed" << endl;
+    }
+
+
+    executed = false;
+    cout << "exec_file failure test" << endl;
+    try {
+    	py::exec_file("none-existing file");
+    }
+    catch (std::invalid_argument & err) {
+    	executed = true;
+    }
+    if (executed)
+        cout << "exec_file failure test passed" << endl;
+    else {
+        cout << "exec_file failure test failed" << endl;
+    }
+
+    executed = false;
+    cout << "eval failure test" << endl;
+    try {
+    	py::eval("print('dummy')");
+    }
+    catch (py::error_already_set & err) {
+    	executed = true;
+    }
+    if (executed)
+        cout << "eval failure test passed" << endl;
+    else {
+        cout << "eval failure test failed" << endl;
+    }
+}
+
+void init_ex18(py::module & m) {
+	m.def("example18", &example18);
+}
+
+

example/example18.py

+from example import example18
+
+example18()
+
+

example/example18.ref

+exec test
+Hello World!
+exec passed
+eval test
+eval passed
+exec_statement test
+exec_statement passed
+exec_file test
+exec_file passed
+exec failure test
+exec failure test passed
+exec_file failure test
+exec_file failure test passed
+eval failure test
+eval failure test passed

example/example18_call.py

+call_test2(y)
\ No newline at end of file

include/pybind11/exec.h

+/*
+    pybind11/exec.h: Functions to execute python from C++. Based on code from boost.python.
+
+    Copyright (c) 2005 Stefan Seefeld
+
+    This code is based on the boost.python implementation, so a different license applies to this file.
+
+    Boost Software License - Version 1.0 - August 17th, 2003
+
+	Permission is hereby granted, free of charge, to any person or organization
+	obtaining a copy of the software and accompanying documentation covered by
+	this license (the "Software") to use, reproduce, display, distribute,
+	execute, and transmit the Software, and to prepare derivative works of the
+	Software, and to permit third-parties to whom the Software is furnished to
+	do so, all subject to the following:
+
+	The copyright notices in the Software and this entire statement, including
+	the above license grant, this restriction and the following disclaimer,
+	must be included in all copies of the Software, in whole or in part, and
+	all derivative works of the Software, unless such copies or derivative
+	works are solely in the form of machine-executable object code generated by
+	a source language processor.
+
+	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+	FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+	SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+	FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+	ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+	DEALINGS IN THE SOFTWARE.
+
+*/
+
+#pragma once
+
+#include "pytypes.h"
+
+NAMESPACE_BEGIN(pybind11)
+
+
+
+inline object eval (const std::string& st, object global = object(), object local = object()) {
+    if (!global) {
+        if (PyObject *g = PyEval_GetGlobals())
+            global = object(g, true);
+        else
+            global = dict();
+    }
+    if (!local)
+        local = global;
+
+    PyObject *res = PyRun_String(st.c_str() , Py_eval_input, global.ptr(), local.ptr());
+
+    if (res == nullptr)
+        throw error_already_set();
+
+    return {res, false};
+}
+
+inline object exec (const std::string& st, object global = object(), object local = object()) {
+    if (!global) {
+        if (PyObject *g = PyEval_GetGlobals())
+            global = object(g, true);
+        else
+            global = dict();
+    }
+    if (!local)
+        local = global;
+
+    PyObject *res = PyRun_String(st.c_str() , Py_file_input, global.ptr(), local.ptr());
+
+    if (res == nullptr)
+        throw error_already_set();
+
+    return {res, false};
+}
+
+inline object exec_statement (const std::string& st, object global = object(), object local = object()) {
+    if (!global) {
+        if (PyObject *g = PyEval_GetGlobals())
+            global = object(g, true);
+        else
+            global = dict();
+    }
+    if (!local)
+        local = global;
+
+    PyObject *res = PyRun_String(st.c_str() , Py_single_input, global.ptr(), local.ptr());
+    if (res == nullptr)
+        throw error_already_set();
+
+    return {res, false};
+}
+
+inline object exec_file(const std::string& filename, object global = object(), object local = object()) {
+    // Set suitable default values for global and local dicts.
+    if (!global) {
+        if (PyObject *g = PyEval_GetGlobals())
+            global = object(g, true);
+    else
+        global = dict();
+    }
+    if (!local) local = global;
+
+    std::string f = filename; //need to copy for the signature of PyFile_FromString
+
+
+    // Let python open the file to avoid potential binary incompatibilities.
+#if PY_VERSION_HEX >= 0x03040000
+    const static int close_it = 1;
+    FILE *fs = _Py_fopen(f.c_str(), "r");
+#elif PY_VERSION_HEX >= 0x03000000
+    const static int close_it = 1;
+    PyObject *fo = Py_BuildValue("s", f.c_str());
+    FILE *fs = _Py_fopen(fo, "r");
+    Py_DECREF(fo);
+#else
+    const static int close_it = 0;
+    PyObject *pyfile = PyFile_FromString(&f.front(), const_cast<char*>("r"));
+    if (!pyfile)
+    	throw std::invalid_argument(std::string(f) + " : no such file");
+    object file(pyfile, false);
+    FILE *fs = PyFile_AsFile(file.ptr());
+#endif
+    if (fs == nullptr)
+    	throw std::invalid_argument(std::string(f) + " : could not be opened");
+
+    PyObject* res = PyRun_FileEx(fs,
+                f.c_str(),
+                Py_file_input,
+                global.ptr(), local.ptr(),
+				close_it);
+
+    if (res == nullptr)
+        throw error_already_set();
+
+    return {res, false};
+
+}
+
+inline object exec (str string, object global = object(), object local = object()) {
+    return exec(static_cast<std::string>(string), global, local);
+}
+
+inline object eval (str string, object global = object(), object local = object()) {
+    return eval(static_cast<std::string>(string), global, local);
+}
+
+inline object exec_file(str filename, object global = object(), object local = object()) {
+    return exec_file(static_cast<std::string>(filename), global, local);
+}
+inline object exec_statement (str string, object global = object(), object local = object()) {
+    return exec_statement(static_cast<std::string>(string), global, local);
+}
+
+NAMESPACE_END(pybind11)