errors: New package

With just one function - errors.New() - to create new error with given
text.

This will be soon used in Pyx/nogil context package to create context.canceled
and context.deadlineExceeded errors.

Pyx/nogil only for now.

MANIFEST.in

 include COPYING README.rst CHANGELOG.rst tox.ini pyproject.toml trun
 include golang/libgolang.h
 include golang/runtime/libgolang.cpp
+include golang/errors.h
+include golang/errors.cpp
 include golang/sync.h
 include golang/sync.cpp
 include golang/time.h

golang/_errors.pxd

+# cython: language_level=2
+# Copyright (C) 2019  Nexedi SA and Contributors.
+#                     Kirill Smelkov <kirr@nexedi.com>
+#
+# This program is free software: you can Use, Study, Modify and Redistribute
+# it under the terms of the GNU General Public License version 3, or (at your
+# option) any later version, as published by the Free Software Foundation.
+#
+# You can also Link and Combine this program with other software covered by
+# the terms of any of the Free Software licenses or any of the Open Source
+# Initiative approved licenses and Convey the resulting work. Corresponding
+# source of such a combination shall include the source code for all other
+# software used.
+#
+# This program is distributed WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+#
+# See COPYING file for full licensing terms.
+# See https://www.nexedi.com/licensing for rationale and options.
+"""Package errors mirrors Go package errors.
+
+ - `New` creates new error with provided text.
+
+See also https://golang.org/pkg/errors for Go errors package documentation.
+"""
+
+from golang cimport error
+from libcpp.string cimport string
+
+cdef extern from "golang/errors.h" namespace "golang::errors" nogil:
+    error New(const string& text)

golang/errors.cpp

+// Copyright (C) 2019  Nexedi SA and Contributors.
+//                     Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+// Package errors mirrors Go package errors.
+// See errors.h for package overview.
+
+#include "golang/errors.h"
+using std::string;
+
+
+// golang::errors::
+namespace golang {
+namespace errors {
+
+// _TextError implements error with text string created by New.
+struct _TextError final : _error, object {
+    string _text;
+
+    void incref() {
+        object::incref();
+    }
+    void decref() {
+        if (__decref())
+            delete this;
+    }
+    ~_TextError() {}
+
+    _TextError(const string& text) : _text(text) {}
+
+    string Error() {
+        return _text;
+    }
+};
+
+error New(const string& text) {
+    return adoptref(static_cast<_error*>(new _TextError(text)));
+}
+
+}}  // golang::errors::

golang/errors.h

+#ifndef _NXD_LIBGOLANG_ERRORS_H
+#define _NXD_LIBGOLANG_ERRORS_H
+
+// Copyright (C) 2019  Nexedi SA and Contributors.
+//                     Kirill Smelkov <kirr@nexedi.com>
+//
+// This program is free software: you can Use, Study, Modify and Redistribute
+// it under the terms of the GNU General Public License version 3, or (at your
+// option) any later version, as published by the Free Software Foundation.
+//
+// You can also Link and Combine this program with other software covered by
+// the terms of any of the Free Software licenses or any of the Open Source
+// Initiative approved licenses and Convey the resulting work. Corresponding
+// source of such a combination shall include the source code for all other
+// software used.
+//
+// This program is distributed WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+// See COPYING file for full licensing terms.
+// See https://www.nexedi.com/licensing for rationale and options.
+
+// Package errors mirrors Go package errors.
+//
+//  - `New` creates new error with provided text.
+//
+// See also https://golang.org/pkg/errors for Go errors package documentation.
+
+#include <golang/libgolang.h>
+
+// golang::errors::
+namespace golang {
+namespace errors {
+
+// New creates new error with provided text.
+LIBGOLANG_API error New(const std::string& text);
+
+}}  // golang::errors::
+
+#endif  // _NXD_LIBGOLANG_ERRORS_H

golang/errors.pxd

+# cython: language_level=2
+# Copyright (C) 2019  Nexedi SA and Contributors.
+#                     Kirill Smelkov <kirr@nexedi.com>
+#
+# This program is free software: you can Use, Study, Modify and Redistribute
+# it under the terms of the GNU General Public License version 3, or (at your
+# option) any later version, as published by the Free Software Foundation.
+#
+# You can also Link and Combine this program with other software covered by
+# the terms of any of the Free Software licenses or any of the Open Source
+# Initiative approved licenses and Convey the resulting work. Corresponding
+# source of such a combination shall include the source code for all other
+# software used.
+#
+# This program is distributed WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+#
+# See COPYING file for full licensing terms.
+# See https://www.nexedi.com/licensing for rationale and options.
+"""Package errors mirrors Go package errors.
+
+See _errors.pxd for package documentation.
+"""
+
+# redirect cimport: golang.errors -> golang._errors (see __init__.pxd for rationale)
+from golang._errors cimport *

golang/pyx/build.py

@@ -166,6 +166,9 @@ def Extension(name, sources, **kw):
     dependv.append('%s/golang/libgolang.h'  % pygo)
     dependv.append('%s/golang/_golang.pxd'  % pygo)
     dependv.append('%s/golang/__init__.pxd' % pygo)
+    dependv.append('%s/golang/errors.h'     % pygo)
+    dependv.append('%s/golang/errors.pxd'   % pygo)
+    dependv.append('%s/golang/_errors.pxd'  % pygo)
     dependv.append('%s/golang/sync.h'       % pygo)
     dependv.append('%s/golang/sync.pxd'     % pygo)
     dependv.append('%s/golang/_sync.pxd'    % pygo)

setup.py

@@ -193,10 +193,12 @@ setup(
 
     x_dsos      = [DSO('golang.runtime.libgolang',
                         ['golang/runtime/libgolang.cpp',
+                         'golang/errors.cpp',
                          'golang/sync.cpp',
                          'golang/time.cpp'],
                         depends = [
                             'golang/libgolang.h',
+                            'golang/errors.h',
                             'golang/sync.h',
                             'golang/time.h'],
                         include_dirs    = ['.', '3rdparty/include'],