ext: Upgrade PyBind11 to version 2.2.1
This upgrade is necessary for pybind to build with GCC 7.2. We still need to add the patch for stl.h. MSC_FULL_VER change is no longer needed. See https://gem5-review.googlesource.com/c/public/gem5/+/2230 Change-Id: I806729217d022070583994c2dfcaa74476aef30f Signed-off-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-on: https://gem5-review.googlesource.com/5801 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
This commit is contained in:
@@ -57,11 +57,11 @@ specification.
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struct buffer_info {
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void *ptr;
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size_t itemsize;
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ssize_t itemsize;
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std::string format;
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int ndim;
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std::vector<size_t> shape;
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std::vector<size_t> strides;
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ssize_t ndim;
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std::vector<ssize_t> shape;
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std::vector<ssize_t> strides;
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};
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To create a C++ function that can take a Python buffer object as an argument,
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@@ -95,11 +95,11 @@ buffer objects (e.g. a NumPy matrix).
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throw std::runtime_error("Incompatible buffer dimension!");
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auto strides = Strides(
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info.strides[rowMajor ? 0 : 1] / sizeof(Scalar),
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info.strides[rowMajor ? 1 : 0] / sizeof(Scalar));
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info.strides[rowMajor ? 0 : 1] / (py::ssize_t)sizeof(Scalar),
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info.strides[rowMajor ? 1 : 0] / (py::ssize_t)sizeof(Scalar));
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auto map = Eigen::Map<Matrix, 0, Strides>(
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static_cat<Scalar *>(info.ptr), info.shape[0], info.shape[1], strides);
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static_cast<Scalar *>(info.ptr), info.shape[0], info.shape[1], strides);
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new (&m) Matrix(map);
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});
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@@ -111,18 +111,14 @@ as follows:
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.def_buffer([](Matrix &m) -> py::buffer_info {
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return py::buffer_info(
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m.data(), /* Pointer to buffer */
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sizeof(Scalar), /* Size of one scalar */
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/* Python struct-style format descriptor */
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py::format_descriptor<Scalar>::format(),
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/* Number of dimensions */
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2,
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/* Buffer dimensions */
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{ (size_t) m.rows(),
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(size_t) m.cols() },
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/* Strides (in bytes) for each index */
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m.data(), /* Pointer to buffer */
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sizeof(Scalar), /* Size of one scalar */
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py::format_descriptor<Scalar>::format(), /* Python struct-style format descriptor */
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2, /* Number of dimensions */
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{ m.rows(), m.cols() }, /* Buffer dimensions */
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{ sizeof(Scalar) * (rowMajor ? m.cols() : 1),
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sizeof(Scalar) * (rowMajor ? 1 : m.rows()) }
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/* Strides (in bytes) for each index */
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);
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})
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@@ -194,7 +190,7 @@ expects the type followed by field names:
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};
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// ...
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PYBIND11_PLUGIN(test) {
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PYBIND11_MODULE(test, m) {
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// ...
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PYBIND11_NUMPY_DTYPE(A, x, y);
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@@ -202,6 +198,13 @@ expects the type followed by field names:
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/* now both A and B can be used as template arguments to py::array_t */
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}
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The structure should consist of fundamental arithmetic types, ``std::complex``,
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previously registered substructures, and arrays of any of the above. Both C++
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arrays and ``std::array`` are supported. While there is a static assertion to
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prevent many types of unsupported structures, it is still the user's
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responsibility to use only "plain" structures that can be safely manipulated as
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raw memory without violating invariants.
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Vectorizing functions
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=====================
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@@ -236,27 +239,13 @@ by the compiler. The result is returned as a NumPy array of type
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The scalar argument ``z`` is transparently replicated 4 times. The input
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arrays ``x`` and ``y`` are automatically converted into the right types (they
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are of type ``numpy.dtype.int64`` but need to be ``numpy.dtype.int32`` and
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``numpy.dtype.float32``, respectively)
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``numpy.dtype.float32``, respectively).
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Sometimes we might want to explicitly exclude an argument from the vectorization
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because it makes little sense to wrap it in a NumPy array. For instance,
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suppose the function signature was
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.. note::
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.. code-block:: cpp
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double my_func(int x, float y, my_custom_type *z);
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This can be done with a stateful Lambda closure:
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.. code-block:: cpp
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// Vectorize a lambda function with a capture object (e.g. to exclude some arguments from the vectorization)
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m.def("vectorized_func",
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[](py::array_t<int> x, py::array_t<float> y, my_custom_type *z) {
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auto stateful_closure = [z](int x, float y) { return my_func(x, y, z); };
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return py::vectorize(stateful_closure)(x, y);
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}
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);
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Only arithmetic, complex, and POD types passed by value or by ``const &``
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reference are vectorized; all other arguments are passed through as-is.
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Functions taking rvalue reference arguments cannot be vectorized.
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In cases where the computation is too complicated to be reduced to
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``vectorize``, it will be necessary to create and access the buffer contents
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@@ -295,10 +284,8 @@ simply using ``vectorize``).
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return result;
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}
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PYBIND11_PLUGIN(test) {
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py::module m("test");
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PYBIND11_MODULE(test, m) {
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m.def("add_arrays", &add_arrays, "Add two NumPy arrays");
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return m.ptr();
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}
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.. seealso::
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@@ -322,17 +309,17 @@ where ``N`` gives the required dimensionality of the array:
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m.def("sum_3d", [](py::array_t<double> x) {
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auto r = x.unchecked<3>(); // x must have ndim = 3; can be non-writeable
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double sum = 0;
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for (size_t i = 0; i < r.shape(0); i++)
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for (size_t j = 0; j < r.shape(1); j++)
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for (size_t k = 0; k < r.shape(2); k++)
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for (ssize_t i = 0; i < r.shape(0); i++)
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for (ssize_t j = 0; j < r.shape(1); j++)
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for (ssize_t k = 0; k < r.shape(2); k++)
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sum += r(i, j, k);
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return sum;
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});
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m.def("increment_3d", [](py::array_t<double> x) {
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auto r = x.mutable_unchecked<3>(); // Will throw if ndim != 3 or flags.writeable is false
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for (size_t i = 0; i < r.shape(0); i++)
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for (size_t j = 0; j < r.shape(1); j++)
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for (size_t k = 0; k < r.shape(2); k++)
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for (ssize_t i = 0; i < r.shape(0); i++)
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for (ssize_t j = 0; j < r.shape(1); j++)
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for (ssize_t k = 0; k < r.shape(2); k++)
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r(i, j, k) += 1.0;
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}, py::arg().noconvert());
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@@ -33,12 +33,50 @@ The reverse direction uses the following syntax:
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When conversion fails, both directions throw the exception :class:`cast_error`.
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.. _python_libs:
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Accessing Python libraries from C++
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===================================
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It is also possible to import objects defined in the Python standard
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library or available in the current Python environment (``sys.path``) and work
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with these in C++.
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This example obtains a reference to the Python ``Decimal`` class.
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.. code-block:: cpp
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// Equivalent to "from decimal import Decimal"
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py::object Decimal = py::module::import("decimal").attr("Decimal");
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.. code-block:: cpp
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// Try to import scipy
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py::object scipy = py::module::import("scipy");
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return scipy.attr("__version__");
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.. _calling_python_functions:
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Calling Python functions
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========================
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It is also possible to call python functions via ``operator()``.
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It is also possible to call Python classes, functions and methods
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via ``operator()``.
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.. code-block:: cpp
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// Construct a Python object of class Decimal
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py::object pi = Decimal("3.14159");
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.. code-block:: cpp
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// Use Python to make our directories
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py::object os = py::module::import("os");
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py::object makedirs = os.attr("makedirs");
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makedirs("/tmp/path/to/somewhere");
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One can convert the result obtained from Python to a pure C++ version
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if a ``py::class_`` or type conversion is defined.
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.. code-block:: cpp
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@@ -46,6 +84,37 @@ It is also possible to call python functions via ``operator()``.
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py::object result_py = f(1234, "hello", some_instance);
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MyClass &result = result_py.cast<MyClass>();
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.. _calling_python_methods:
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Calling Python methods
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========================
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To call an object's method, one can again use ``.attr`` to obtain access to the
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Python method.
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.. code-block:: cpp
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// Calculate e^π in decimal
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py::object exp_pi = pi.attr("exp")();
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py::print(py::str(exp_pi));
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In the example above ``pi.attr("exp")`` is a *bound method*: it will always call
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the method for that same instance of the class. Alternately one can create an
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*unbound method* via the Python class (instead of instance) and pass the ``self``
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object explicitly, followed by other arguments.
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.. code-block:: cpp
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py::object decimal_exp = Decimal.attr("exp");
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// Compute the e^n for n=0..4
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for (int n = 0; n < 5; n++) {
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py::print(decimal_exp(Decimal(n));
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}
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Keyword arguments
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=================
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Keyword arguments are also supported. In Python, there is the usual call syntax:
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.. code-block:: python
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@@ -62,6 +131,9 @@ In C++, the same call can be made using:
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using namespace pybind11::literals; // to bring in the `_a` literal
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f(1234, "say"_a="hello", "to"_a=some_instance); // keyword call in C++
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Unpacking arguments
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===================
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Unpacking of ``*args`` and ``**kwargs`` is also possible and can be mixed with
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other arguments:
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@@ -90,7 +162,7 @@ Generalized unpacking according to PEP448_ is also supported:
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.. seealso::
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The file :file:`tests/test_python_types.cpp` contains a complete
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The file :file:`tests/test_pytypes.cpp` contains a complete
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example that demonstrates passing native Python types in more detail. The
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file :file:`tests/test_callbacks.cpp` presents a few examples of calling
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Python functions from C++, including keywords arguments and unpacking.
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@@ -21,19 +21,81 @@ expected in Python:
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auto args = py::make_tuple("unpacked", true);
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py::print("->", *args, "end"_a="<-"); // -> unpacked True <-
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.. _ostream_redirect:
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Capturing standard output from ostream
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======================================
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Often, a library will use the streams ``std::cout`` and ``std::cerr`` to print,
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but this does not play well with Python's standard ``sys.stdout`` and ``sys.stderr``
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redirection. Replacing a library's printing with `py::print <print>` may not
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be feasible. This can be fixed using a guard around the library function that
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redirects output to the corresponding Python streams:
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.. code-block:: cpp
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#include <pybind11/iostream.h>
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...
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// Add a scoped redirect for your noisy code
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m.def("noisy_func", []() {
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py::scoped_ostream_redirect stream(
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std::cout, // std::ostream&
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py::module::import("sys").attr("stdout") // Python output
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);
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call_noisy_func();
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});
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This method respects flushes on the output streams and will flush if needed
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when the scoped guard is destroyed. This allows the output to be redirected in
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real time, such as to a Jupyter notebook. The two arguments, the C++ stream and
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the Python output, are optional, and default to standard output if not given. An
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extra type, `py::scoped_estream_redirect <scoped_estream_redirect>`, is identical
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except for defaulting to ``std::cerr`` and ``sys.stderr``; this can be useful with
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`py::call_guard`, which allows multiple items, but uses the default constructor:
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.. code-block:: py
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// Alternative: Call single function using call guard
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m.def("noisy_func", &call_noisy_function,
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py::call_guard<py::scoped_ostream_redirect,
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py::scoped_estream_redirect>());
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The redirection can also be done in Python with the addition of a context
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manager, using the `py::add_ostream_redirect() <add_ostream_redirect>` function:
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.. code-block:: cpp
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py::add_ostream_redirect(m, "ostream_redirect");
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The name in Python defaults to ``ostream_redirect`` if no name is passed. This
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creates the following context manager in Python:
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.. code-block:: python
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with ostream_redirect(stdout=True, stderr=True):
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noisy_function()
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It defaults to redirecting both streams, though you can use the keyword
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arguments to disable one of the streams if needed.
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.. note::
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The above methods will not redirect C-level output to file descriptors, such
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as ``fprintf``. For those cases, you'll need to redirect the file
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descriptors either directly in C or with Python's ``os.dup2`` function
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in an operating-system dependent way.
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.. _eval:
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Evaluating Python expressions from strings and files
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====================================================
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pybind11 provides the :func:`eval` and :func:`eval_file` functions to evaluate
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pybind11 provides the `eval`, `exec` and `eval_file` functions to evaluate
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Python expressions and statements. The following example illustrates how they
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can be used.
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Both functions accept a template parameter that describes how the argument
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should be interpreted. Possible choices include ``eval_expr`` (isolated
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expression), ``eval_single_statement`` (a single statement, return value is
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always ``none``), and ``eval_statements`` (sequence of statements, return value
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is always ``none``).
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.. code-block:: cpp
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// At beginning of file
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@@ -48,10 +110,35 @@ is always ``none``).
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int result = py::eval("my_variable + 10", scope).cast<int>();
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// Evaluate a sequence of statements
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py::eval<py::eval_statements>(
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py::exec(
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"print('Hello')\n"
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"print('world!');",
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scope);
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// Evaluate the statements in an separate Python file on disk
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py::eval_file("script.py", scope);
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C++11 raw string literals are also supported and quite handy for this purpose.
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The only requirement is that the first statement must be on a new line following
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the raw string delimiter ``R"(``, ensuring all lines have common leading indent:
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.. code-block:: cpp
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py::exec(R"(
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x = get_answer()
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if x == 42:
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print('Hello World!')
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else:
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print('Bye!')
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)", scope
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);
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.. note::
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`eval` and `eval_file` accept a template parameter that describes how the
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string/file should be interpreted. Possible choices include ``eval_expr``
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(isolated expression), ``eval_single_statement`` (a single statement, return
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value is always ``none``), and ``eval_statements`` (sequence of statements,
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return value is always ``none``). `eval` defaults to ``eval_expr``,
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`eval_file` defaults to ``eval_statements`` and `exec` is just a shortcut
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for ``eval<eval_statements>``.
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Reference in New Issue
Block a user