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complete rewrite of eval/exec patch

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Wenzel Jakob 2016-07-08 10:52:10 +02:00
parent c6ad2c4993
commit 0d3fc3566a
6 changed files with 178 additions and 282 deletions
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44
docs/advanced.rst
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@ -1612,32 +1612,38 @@ work, it is important that all lines are indented consistently, i.e.:
.. [#f4] http://www.sphinx-doc.org
.. [#f5] http://github.com/pybind/python_example
Calling Python from C++
=======================
Evaluating Python expressions from strings and files
====================================================
Pybind11 also allows to call python code from C++. Note that this code assumes, that the intepreter is already initialized.
pybind11 provides the :func:`eval` and :func:`eval_file` functions to evaluate
Python expressions and statements. The following example illustrates how they
can be used.
Both functions accept a template parameter that describes how the argument
should be interpreted. Possible choices include ``eval_expr`` (isolated
expression), ``eval_single_statement`` (a single statement, return value is
always ``none``), and ``eval_statements`` (sequence of statements, return value
is always ``none``).
.. code-block:: cpp
// get the main module, so we can access and declare stuff
py::module main_module = py::module::import("__main__");
// At beginning of file
#include <pybind11/eval.h>
//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);
// Evaluate in scope of main module
py::object scope = py::module::import("__main__").attr("__dict__");
//execute a single statement
py::exec_statement("x=42", main_namespace);
// Evaluate an isolated expression
int result = py::eval("my_variable + 10", scope).cast<int>();
//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;
// Evaluate a sequence of statements
py::eval<py::eval_statements>(
"print('Hello')\n"
"print('world!');",
scope);
//or we can execute a file within the same content
py::exec_file("my_script.py", main_namespace);
// Evaluate the statements in an separate Python file on disk
py::eval_file("script.py", scope);

22
docs/reference.rst
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@ -245,25 +245,3 @@ Passing extra arguments to the def function
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.

122
example/example18.cpp
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@ -1,5 +1,5 @@
/*
example/example18.cpp -- Usage of exec, eval etc.
example/example18.cpp -- Usage of eval() and eval_file()
Copyright (c) 2016 Klemens D. Morgenstern
@ -8,29 +8,30 @@
*/
#include <pybind11/exec.h>
#include <pybind11/eval.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;
bool ok = false;
main_module.def("call_test", [&]()-> int {executed = true; return 42;});
main_module.def("call_test", [&]() -> int {
ok = true;
return 42;
});
cout << "exec test" << endl;
cout << "eval_statements test" << endl;
py::exec(
auto result = py::eval<py::eval_statements>(
"print('Hello World!');\n"
"x = call_test();",
main_namespace);
"x = call_test();", main_namespace);
if (executed)
cout << "exec passed" << endl;
else {
cout << "exec failed" << endl;
}
if (ok && result == py::none())
cout << "eval_statements passed" << endl;
else
cout << "eval_statements failed" << endl;
cout << "eval test" << endl;
@ -38,83 +39,64 @@ void example18() {
if (val.cast<int>() == 42)
cout << "eval passed" << endl;
else {
else
cout << "eval failed" << endl;
}
ok = false;
cout << "eval_single_statement test" << endl;
executed = false;
cout << "exec_statement test" << endl;
py::eval<py::eval_single_statement>(
"y = call_test();", main_namespace);
py::exec_statement("y = call_test();", main_namespace);
if (ok)
cout << "eval_single_statement passed" << endl;
else
cout << "eval_single_statement failed" << endl;
if (executed)
cout << "exec_statement passed" << endl;
else {
cout << "exec_statement failed" << endl;
}
cout << "exec_file test" << endl;
cout << "eval_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;
result = py::eval_file("example18_call.py", main_namespace);
} catch (...) {
result = py::eval_file("example/example18_call.py", main_namespace);
}
if (val_out == 42 && result == py::none())
cout << "eval_file passed" << endl;
else
cout << "eval_file 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;
ok = false;
cout << "eval failure test" << endl;
try {
py::eval("print('dummy')");
py::eval("nonsense code ...");
} catch (py::error_already_set &) {
PyErr_Clear();
ok = true;
}
catch (py::error_already_set & err) {
executed = true;
}
if (executed)
if (ok)
cout << "eval failure test passed" << endl;
else {
else
cout << "eval failure test failed" << endl;
ok = false;
cout << "eval_file failure test" << endl;
try {
py::eval_file("nonexisting file");
} catch (std::exception &) {
ok = true;
}
if (ok)
cout << "eval_file failure test passed" << endl;
else
cout << "eval_file failure test failed" << endl;
}
void init_ex18(py::module & m) {
m.def("example18", &example18);
m.def("example18", &example18);
}

20
example/example18.ref
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@ -1,15 +1,13 @@
exec test
Hello World!
exec passed
eval_statements test
eval_statements 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_single_statement test
eval_single_statement passed
eval_file test
eval_file passed
eval failure test
eval failure test passed
eval_file failure test
eval_file failure test passed
Hello World!

88
include/pybind11/eval.h Normal file
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@ -0,0 +1,88 @@
/*
pybind11/exec.h: Support for evaluating Python expressions and statements
from strings and files
Copyright (c) 2016 Klemens Morgenstern <klemens.morgenstern@ed-chemnitz.de> and
Wenzel Jakob <wenzel.jakob@epfl.ch>
All rights reserved. Use of this source code is governed by a
BSD-style license that can be found in the LICENSE file.
*/
#pragma once
#pragma once
#include "pytypes.h"
NAMESPACE_BEGIN(pybind11)
enum eval_mode {
/// Evaluate a string containing an isolated expression
eval_expr,
/// Evaluate a string containing a single statement. Returns \c none
eval_single_statement,
/// Evaluate a string containing a sequence of statement. Returns \c none
eval_statements
};
template <eval_mode mode = eval_expr>
object eval(const std::string& str, object global = object(), object local = object()) {
if (!global) {
global = object(PyEval_GetGlobals(), true);
if (!global)
global = dict();
}
if (!local)
local = global;
int start;
switch (mode) {
case eval_expr: start = Py_eval_input; break;
case eval_single_statement: start = Py_single_input; break;
case eval_statements: start = Py_file_input; break;
default: pybind11_fail("invalid evaluation mode");
}
object result(PyRun_String(str.c_str(), start, global.ptr(), local.ptr()), false);
if (!result)
throw error_already_set();
return result;
}
template <eval_mode mode = eval_statements>
object eval_file(const std::string& fname, object global = object(), object local = object()) {
if (!global) {
global = object(PyEval_GetGlobals(), true);
if (!global)
global = dict();
}
if (!local)
local = global;
int start;
switch (mode) {
case eval_expr: start = Py_eval_input; break;
case eval_single_statement: start = Py_single_input; break;
case eval_statements: start = Py_file_input; break;
default: pybind11_fail("invalid evaluation mode");
}
FILE *f = fopen(fname.c_str(), "r");
if (!f)
pybind11_fail("File \"" + fname + "\" could not be opened!");
object result(PyRun_FileEx(f, fname.c_str(), Py_file_input, global.ptr(),
local.ptr(), 1),
false);
if (!result)
throw error_already_set();
return result;
}
NAMESPACE_END(pybind11)

156
include/pybind11/exec.h
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@ -1,156 +0,0 @@
/*
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)