LSSTApplications  18.1.0
LSSTDataManagementBasePackage
Exception.h
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1 /*
2  * This file is part of pex_exceptions.
3  *
4  * Developed for the LSST Data Management System.
5  * This product includes software developed by the LSST Project
6  * (https://www.lsst.org).
7  * See the COPYRIGHT file at the top-level directory of this distribution
8  * for details of code ownership.
9  *
10  * This program is free software: you can redistribute it and/or modify
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14  *
15  * This program is distributed in the hope that it will be useful,
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17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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22  */
23 
24 #ifndef LSST_PEX_EXCEPTIONS_PYTHON_EXCEPTION_H
25 #define LSST_PEX_EXCEPTIONS_PYTHON_EXCEPTION_H
26 
27 #include <string>
28 
29 #include <pybind11/pybind11.h>
30 
32 
33 namespace lsst {
34 namespace pex {
35 namespace exceptions {
36 namespace python {
37 
51 template <typename T, typename E = lsst::pex::exceptions::Exception>
52 pybind11::class_<T, E> declareException(pybind11::module &mod, const std::string &name,
53  const std::string &base) {
54  namespace py = pybind11;
55 
56  // Wrap T as a new Python exception type with *name* and add it to the module
57  //
58  // Note that all created C++ wrapped type derive from Exception here.
59  // It is only in the pure Python wrapper layer that they get embedded in
60  // a subclass of the requested base.
61  py::class_<T, E> cls(mod, name.c_str());
62 
63  // Declare T wrapped by cls as a pex exception and register it
64  // this relies on the pure Python function "declare" defined in "wrappers"
65  // to create a corresponding Python type derived from Python standard Exception
66  auto exceptions =
67  py::reinterpret_steal<py::object>(PyImport_ImportModule("lsst.pex.exceptions.wrappers"));
68  if (!exceptions.ptr()) {
69  PyErr_SetString(PyExc_SystemError, "import failed");
70  throw py::error_already_set();
71  }
72 
73  auto declare = py::reinterpret_steal<py::object>(PyObject_GetAttrString(exceptions.ptr(), "declare"));
74  if (!declare.ptr()) {
75  PyErr_SetString(PyExc_SystemError, "could not get declare function from Python");
76  throw py::error_already_set();
77  }
78 
79  auto baseCls = py::reinterpret_steal<py::object>(PyObject_GetAttrString(exceptions.ptr(), base.c_str()));
80  if (!baseCls.ptr()) {
81  PyErr_SetString(PyExc_SystemError, "could not get base class");
82  throw py::error_already_set();
83  }
84 
85  auto exceptionName = py::reinterpret_steal<py::object>(PYBIND11_FROM_STRING(name.c_str()));
86  if (!exceptionName.ptr()) {
87  PyErr_SetString(PyExc_SystemError, "could not create name string");
88  throw py::error_already_set();
89  }
90 
91  auto result = py::reinterpret_steal<py::object>(PyObject_CallFunctionObjArgs(
92  declare.ptr(), mod.ptr(), exceptionName.ptr(), baseCls.ptr(), cls.ptr(), NULL));
93  if (!result.ptr()) {
94  PyErr_SetString(PyExc_SystemError, "could not declare exception");
95  throw py::error_already_set();
96  }
97 
98  return cls;
99 }
100 
101 } // namespace python
102 } // namespace exceptions
103 } // namespace pex
104 } // namespace lsst
105 
106 #endif
pybind11::class_< T, E > declareException(pybind11::module &mod, const std::string &name, const std::string &base)
Helper function for pybind11, used to define new types of exceptions.
Definition: Exception.h:52
py::object result
Definition: schema.cc:418
STL class.
A base class for image defects.
T c_str(T... args)
def declare(module, exception_name, base, wrapped_class)
Definition: wrappers.py:152