[Python-checkins] gh-91291: Accept attributes as keyword arguments in decimal.localcontext (#32242)
JelleZijlstra
webhook-mailer at python.org
Fri Apr 22 00:27:20 EDT 2022
https://github.com/python/cpython/commit/bcf14ae4336fced718c00edc34b9191c2b48525a
commit: bcf14ae4336fced718c00edc34b9191c2b48525a
branch: main
author: Sam Ezeh <sam.z.ezeh at gmail.com>
committer: JelleZijlstra <jelle.zijlstra at gmail.com>
date: 2022-04-21T21:27:15-07:00
summary:
gh-91291: Accept attributes as keyword arguments in decimal.localcontext (#32242)
Co-authored-by: Jelle Zijlstra <jelle.zijlstra at gmail.com>
files:
A Misc/NEWS.d/next/Library/2022-04-01-21-44-00.bpo-47135.TvkKB-.rst
M Doc/library/decimal.rst
M Lib/_pydecimal.py
M Lib/test/test_decimal.py
M Modules/_decimal/_decimal.c
M Modules/_decimal/docstrings.h
diff --git a/Doc/library/decimal.rst b/Doc/library/decimal.rst
index e759c5cf23b9e..2ad84f20b5560 100644
--- a/Doc/library/decimal.rst
+++ b/Doc/library/decimal.rst
@@ -925,12 +925,13 @@ Each thread has its own current context which is accessed or changed using the
You can also use the :keyword:`with` statement and the :func:`localcontext`
function to temporarily change the active context.
-.. function:: localcontext(ctx=None)
+.. function:: localcontext(ctx=None, \*\*kwargs)
Return a context manager that will set the current context for the active thread
to a copy of *ctx* on entry to the with-statement and restore the previous context
when exiting the with-statement. If no context is specified, a copy of the
- current context is used.
+ current context is used. The *kwargs* argument is used to set the attributes
+ of the new context.
For example, the following code sets the current decimal precision to 42 places,
performs a calculation, and then automatically restores the previous context::
@@ -942,6 +943,21 @@ function to temporarily change the active context.
s = calculate_something()
s = +s # Round the final result back to the default precision
+ Using keyword arguments, the code would be the following::
+
+ from decimal import localcontext
+
+ with localcontext(prec=42) as ctx:
+ s = calculate_something()
+ s = +s
+
+ Raises :exc:`TypeError` if *kwargs* supplies an attribute that :class:`Context` doesn't
+ support. Raises either :exc:`TypeError` or :exc:`ValueError` if *kwargs* supplies an
+ invalid value for an attribute.
+
+ .. versionchanged:: 3.11
+ :meth:`localcontext` now supports setting context attributes through the use of keyword arguments.
+
New contexts can also be created using the :class:`Context` constructor
described below. In addition, the module provides three pre-made contexts:
diff --git a/Lib/_pydecimal.py b/Lib/_pydecimal.py
index 89646fa714c54..f9d6c9901f1f3 100644
--- a/Lib/_pydecimal.py
+++ b/Lib/_pydecimal.py
@@ -441,6 +441,10 @@ class FloatOperation(DecimalException, TypeError):
_current_context_var = contextvars.ContextVar('decimal_context')
+_context_attributes = frozenset(
+ ['prec', 'Emin', 'Emax', 'capitals', 'clamp', 'rounding', 'flags', 'traps']
+)
+
def getcontext():
"""Returns this thread's context.
@@ -464,7 +468,7 @@ def setcontext(context):
del contextvars # Don't contaminate the namespace
-def localcontext(ctx=None):
+def localcontext(ctx=None, **kwargs):
"""Return a context manager for a copy of the supplied context
Uses a copy of the current context if no context is specified
@@ -500,8 +504,14 @@ def sin(x):
>>> print(getcontext().prec)
28
"""
- if ctx is None: ctx = getcontext()
- return _ContextManager(ctx)
+ if ctx is None:
+ ctx = getcontext()
+ ctx_manager = _ContextManager(ctx)
+ for key, value in kwargs.items():
+ if key not in _context_attributes:
+ raise TypeError(f"'{key}' is an invalid keyword argument for this function")
+ setattr(ctx_manager.new_context, key, value)
+ return ctx_manager
##### Decimal class #######################################################
diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index 5e77e3c56cbbc..96f8f7f32c454 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -3665,6 +3665,40 @@ def test_localcontextarg(self):
self.assertIsNot(new_ctx, set_ctx, 'did not copy the context')
self.assertIs(set_ctx, enter_ctx, '__enter__ returned wrong context')
+ def test_localcontext_kwargs(self):
+ with self.decimal.localcontext(
+ prec=10, rounding=ROUND_HALF_DOWN,
+ Emin=-20, Emax=20, capitals=0,
+ clamp=1
+ ) as ctx:
+ self.assertEqual(ctx.prec, 10)
+ self.assertEqual(ctx.rounding, self.decimal.ROUND_HALF_DOWN)
+ self.assertEqual(ctx.Emin, -20)
+ self.assertEqual(ctx.Emax, 20)
+ self.assertEqual(ctx.capitals, 0)
+ self.assertEqual(ctx.clamp, 1)
+
+ self.assertRaises(TypeError, self.decimal.localcontext, precision=10)
+
+ self.assertRaises(ValueError, self.decimal.localcontext, Emin=1)
+ self.assertRaises(ValueError, self.decimal.localcontext, Emax=-1)
+ self.assertRaises(ValueError, self.decimal.localcontext, capitals=2)
+ self.assertRaises(ValueError, self.decimal.localcontext, clamp=2)
+
+ self.assertRaises(TypeError, self.decimal.localcontext, rounding="")
+ self.assertRaises(TypeError, self.decimal.localcontext, rounding=1)
+
+ self.assertRaises(TypeError, self.decimal.localcontext, flags="")
+ self.assertRaises(TypeError, self.decimal.localcontext, traps="")
+ self.assertRaises(TypeError, self.decimal.localcontext, Emin="")
+ self.assertRaises(TypeError, self.decimal.localcontext, Emax="")
+
+ def test_local_context_kwargs_does_not_overwrite_existing_argument(self):
+ ctx = self.decimal.getcontext()
+ ctx.prec = 28
+ with self.decimal.localcontext(prec=10) as ctx2:
+ self.assertEqual(ctx.prec, 28)
+
def test_nested_with_statements(self):
# Use a copy of the supplied context in the block
Decimal = self.decimal.Decimal
diff --git a/Misc/NEWS.d/next/Library/2022-04-01-21-44-00.bpo-47135.TvkKB-.rst b/Misc/NEWS.d/next/Library/2022-04-01-21-44-00.bpo-47135.TvkKB-.rst
new file mode 100644
index 0000000000000..2323c22c007e9
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-04-01-21-44-00.bpo-47135.TvkKB-.rst
@@ -0,0 +1 @@
+:meth:`decimal.localcontext` now accepts context attributes via keyword arguments
diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index 4637b8b34c4ce..8c08847328bc0 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -1156,6 +1156,67 @@ context_setattr(PyObject *self, PyObject *name, PyObject *value)
return PyObject_GenericSetAttr(self, name, value);
}
+static int
+context_setattrs(PyObject *self, PyObject *prec, PyObject *rounding,
+ PyObject *emin, PyObject *emax, PyObject *capitals,
+ PyObject *clamp, PyObject *status, PyObject *traps) {
+
+ int ret;
+ if (prec != Py_None && context_setprec(self, prec, NULL) < 0) {
+ return -1;
+ }
+ if (rounding != Py_None && context_setround(self, rounding, NULL) < 0) {
+ return -1;
+ }
+ if (emin != Py_None && context_setemin(self, emin, NULL) < 0) {
+ return -1;
+ }
+ if (emax != Py_None && context_setemax(self, emax, NULL) < 0) {
+ return -1;
+ }
+ if (capitals != Py_None && context_setcapitals(self, capitals, NULL) < 0) {
+ return -1;
+ }
+ if (clamp != Py_None && context_setclamp(self, clamp, NULL) < 0) {
+ return -1;
+ }
+
+ if (traps != Py_None) {
+ if (PyList_Check(traps)) {
+ ret = context_settraps_list(self, traps);
+ }
+#ifdef EXTRA_FUNCTIONALITY
+ else if (PyLong_Check(traps)) {
+ ret = context_settraps(self, traps, NULL);
+ }
+#endif
+ else {
+ ret = context_settraps_dict(self, traps);
+ }
+ if (ret < 0) {
+ return ret;
+ }
+ }
+ if (status != Py_None) {
+ if (PyList_Check(status)) {
+ ret = context_setstatus_list(self, status);
+ }
+#ifdef EXTRA_FUNCTIONALITY
+ else if (PyLong_Check(status)) {
+ ret = context_setstatus(self, status, NULL);
+ }
+#endif
+ else {
+ ret = context_setstatus_dict(self, status);
+ }
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
static PyObject *
context_clear_traps(PyObject *self, PyObject *dummy UNUSED)
{
@@ -1255,7 +1316,6 @@ context_init(PyObject *self, PyObject *args, PyObject *kwds)
PyObject *clamp = Py_None;
PyObject *status = Py_None;
PyObject *traps = Py_None;
- int ret;
assert(PyTuple_Check(args));
@@ -1267,59 +1327,11 @@ context_init(PyObject *self, PyObject *args, PyObject *kwds)
return -1;
}
- if (prec != Py_None && context_setprec(self, prec, NULL) < 0) {
- return -1;
- }
- if (rounding != Py_None && context_setround(self, rounding, NULL) < 0) {
- return -1;
- }
- if (emin != Py_None && context_setemin(self, emin, NULL) < 0) {
- return -1;
- }
- if (emax != Py_None && context_setemax(self, emax, NULL) < 0) {
- return -1;
- }
- if (capitals != Py_None && context_setcapitals(self, capitals, NULL) < 0) {
- return -1;
- }
- if (clamp != Py_None && context_setclamp(self, clamp, NULL) < 0) {
- return -1;
- }
-
- if (traps != Py_None) {
- if (PyList_Check(traps)) {
- ret = context_settraps_list(self, traps);
- }
-#ifdef EXTRA_FUNCTIONALITY
- else if (PyLong_Check(traps)) {
- ret = context_settraps(self, traps, NULL);
- }
-#endif
- else {
- ret = context_settraps_dict(self, traps);
- }
- if (ret < 0) {
- return ret;
- }
- }
- if (status != Py_None) {
- if (PyList_Check(status)) {
- ret = context_setstatus_list(self, status);
- }
-#ifdef EXTRA_FUNCTIONALITY
- else if (PyLong_Check(status)) {
- ret = context_setstatus(self, status, NULL);
- }
-#endif
- else {
- ret = context_setstatus_dict(self, status);
- }
- if (ret < 0) {
- return ret;
- }
- }
-
- return 0;
+ return context_setattrs(
+ self, prec, rounding,
+ emin, emax, capitals,
+ clamp, status, traps
+ );
}
static PyObject *
@@ -1721,13 +1733,28 @@ PyDec_SetCurrentContext(PyObject *self UNUSED, PyObject *v)
static PyObject *
ctxmanager_new(PyTypeObject *type UNUSED, PyObject *args, PyObject *kwds)
{
- static char *kwlist[] = {"ctx", NULL};
+ static char *kwlist[] = {
+ "ctx", "prec", "rounding",
+ "Emin", "Emax", "capitals",
+ "clamp", "flags", "traps",
+ NULL
+ };
PyDecContextManagerObject *self;
PyObject *local = Py_None;
PyObject *global;
+ PyObject *prec = Py_None;
+ PyObject *rounding = Py_None;
+ PyObject *Emin = Py_None;
+ PyObject *Emax = Py_None;
+ PyObject *capitals = Py_None;
+ PyObject *clamp = Py_None;
+ PyObject *flags = Py_None;
+ PyObject *traps = Py_None;
+
CURRENT_CONTEXT(global);
- if (!PyArg_ParseTupleAndKeywords(args, kwds, "|O", kwlist, &local)) {
+ if (!PyArg_ParseTupleAndKeywords(args, kwds, "|OOOOOOOOO", kwlist, &local,
+ &prec, &rounding, &Emin, &Emax, &capitals, &clamp, &flags, &traps)) {
return NULL;
}
if (local == Py_None) {
@@ -1754,6 +1781,17 @@ ctxmanager_new(PyTypeObject *type UNUSED, PyObject *args, PyObject *kwds)
self->global = global;
Py_INCREF(self->global);
+ int ret = context_setattrs(
+ self->local, prec, rounding,
+ Emin, Emax, capitals,
+ clamp, flags, traps
+ );
+
+ if (ret < 0) {
+ Py_DECREF(self);
+ return NULL;
+ }
+
return (PyObject *)self;
}
diff --git a/Modules/_decimal/docstrings.h b/Modules/_decimal/docstrings.h
index f7fd6e7952998..a1823cdd32b74 100644
--- a/Modules/_decimal/docstrings.h
+++ b/Modules/_decimal/docstrings.h
@@ -30,7 +30,7 @@ Set a new default context.\n\
\n");
PyDoc_STRVAR(doc_localcontext,
-"localcontext($module, /, ctx=None)\n--\n\n\
+"localcontext($module, /, ctx=None, **kwargs)\n--\n\n\
Return a context manager that will set the default context to a copy of ctx\n\
on entry to the with-statement and restore the previous default context when\n\
exiting the with-statement. If no context is specified, a copy of the current\n\
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