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Patch #1675423: PyComplex_AsCComplex() now tries to convert an object 

to complex using its __complex__() method before falling back to the
__float__() method. Therefore, the functions in the cmath module now
can operate on objects that define a __complex__() method.
 (backport)
This commit is contained in:
Georg Brandl 2007-03-17 16:08:45 +00:00
parent 6f187743ff
commit 2b869943fa
5 changed files with 258 additions and 50 deletions
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11
Doc/api/concrete.tex
View File

@ -443,7 +443,9 @@ booleans. The following macros are available, however.
\begin{cfuncdesc}{double}{PyFloat_AsDouble}{PyObject *pyfloat}
Return a C \ctype{double} representation of the contents of
\var{pyfloat}.
\var{pyfloat}. If \var{pyfloat} is not a Python floating point
object but has a \method{__float__} method, this method will first
be called to convert \var{pyfloat} into a float.
\end{cfuncdesc}
\begin{cfuncdesc}{double}{PyFloat_AS_DOUBLE}{PyObject *pyfloat}
@ -558,8 +560,11 @@ typedef struct {
\end{cfuncdesc}
\begin{cfuncdesc}{Py_complex}{PyComplex_AsCComplex}{PyObject *op}
Return the \ctype{Py_complex} value of the complex number
\var{op}.
Return the \ctype{Py_complex} value of the complex number \var{op}.
\versionchanged[If \var{op} is not a Python complex number object
but has a \method{__complex__} method, this method
will first be called to convert \var{op} to a Python
complex number object]{2.6}
\end{cfuncdesc}

9
Doc/lib/libcmath.tex
View File

@ -5,7 +5,14 @@
\modulesynopsis{Mathematical functions for complex numbers.}
This module is always available. It provides access to mathematical
functions for complex numbers. The functions are:
functions for complex numbers. The functions in this module accept
integers, floating-point numbers or complex numbers as arguments.
They will also accept any Python object that has either a
\method{__complex__} or a \method{__float__} method: these methods are
used to convert the object to a complex or floating-point number, respectively, and
the function is then applied to the result of the conversion.
The functions are:
\begin{funcdesc}{acos}{x}
Return the arc cosine of \var{x}.

234
Lib/test/test_cmath.py
View File

@ -1,52 +1,196 @@
#! /usr/bin/env python
""" Simple test script for cmathmodule.c
Roger E. Masse
"""
from test.test_support import run_unittest
import unittest
import cmath, math
from test.test_support import verbose, verify, TestFailed
verify(abs(cmath.log(10) - math.log(10)) < 1e-9)
verify(abs(cmath.log(10,2) - math.log(10,2)) < 1e-9)
try:
cmath.log('a')
except TypeError:
pass
else:
raise TestFailed
class CMathTests(unittest.TestCase):
# list of all functions in cmath
test_functions = [getattr(cmath, fname) for fname in [
'acos', 'acosh', 'asin', 'asinh', 'atan', 'atanh',
'cos', 'cosh', 'exp', 'log', 'log10', 'sin', 'sinh',
'sqrt', 'tan', 'tanh']]
# test first and second arguments independently for 2-argument log
test_functions.append(lambda x : cmath.log(x, 1729. + 0j))
test_functions.append(lambda x : cmath.log(14.-27j, x))
try:
cmath.log(10, 'a')
except TypeError:
pass
else:
raise TestFailed
def cAssertAlmostEqual(self, a, b, rel_eps = 1e-10, abs_eps = 1e-100):
"""Check that two complex numbers are almost equal."""
# the two complex numbers are considered almost equal if
# either the relative error is <= rel_eps or the absolute error
# is tiny, <= abs_eps.
if a == b == 0:
return
absolute_error = abs(a-b)
relative_error = absolute_error/max(abs(a), abs(b))
if relative_error > rel_eps and absolute_error > abs_eps:
self.fail("%s and %s are not almost equal" % (a, b))
def test_constants(self):
e_expected = 2.71828182845904523536
pi_expected = 3.14159265358979323846
self.assertAlmostEqual(cmath.pi, pi_expected, 9,
"cmath.pi is %s; should be %s" % (cmath.pi, pi_expected))
self.assertAlmostEqual(cmath.e, e_expected, 9,
"cmath.e is %s; should be %s" % (cmath.e, e_expected))
testdict = {'acos' : 1.0,
'acosh' : 1.0,
'asin' : 1.0,
'asinh' : 1.0,
'atan' : 0.2,
'atanh' : 0.2,
'cos' : 1.0,
'cosh' : 1.0,
'exp' : 1.0,
'log' : 1.0,
'log10' : 1.0,
'sin' : 1.0,
'sinh' : 1.0,
'sqrt' : 1.0,
'tan' : 1.0,
'tanh' : 1.0}
def test_user_object(self):
# Test automatic calling of __complex__ and __float__ by cmath
# functions
for func in testdict.keys():
f = getattr(cmath, func)
r = f(testdict[func])
if verbose:
print 'Calling %s(%f) = %f' % (func, testdict[func], abs(r))
# some random values to use as test values; we avoid values
# for which any of the functions in cmath is undefined
# (i.e. 0., 1., -1., 1j, -1j) or would cause overflow
cx_arg = 4.419414439 + 1.497100113j
flt_arg = -6.131677725
p = cmath.pi
e = cmath.e
if verbose:
print 'PI = ', abs(p)
print 'E = ', abs(e)
# a variety of non-complex numbers, used to check that
# non-complex return values from __complex__ give an error
non_complexes = ["not complex", 1, 5L, 2., None,
object(), NotImplemented]
# Now we introduce a variety of classes whose instances might
# end up being passed to the cmath functions
# usual case: new-style class implementing __complex__
class MyComplex(object):
def __init__(self, value):
self.value = value
def __complex__(self):
return self.value
# old-style class implementing __complex__
class MyComplexOS:
def __init__(self, value):
self.value = value
def __complex__(self):
return self.value
# classes for which __complex__ raises an exception
class SomeException(Exception):
pass
class MyComplexException(object):
def __complex__(self):
raise SomeException
class MyComplexExceptionOS:
def __complex__(self):
raise SomeException
# some classes not providing __float__ or __complex__
class NeitherComplexNorFloat(object):
pass
class NeitherComplexNorFloatOS:
pass
class MyInt(object):
def __int__(self): return 2
def __long__(self): return 2L
def __index__(self): return 2
class MyIntOS:
def __int__(self): return 2
def __long__(self): return 2L
def __index__(self): return 2
# other possible combinations of __float__ and __complex__
# that should work
class FloatAndComplex(object):
def __float__(self):
return flt_arg
def __complex__(self):
return cx_arg
class FloatAndComplexOS:
def __float__(self):
return flt_arg
def __complex__(self):
return cx_arg
class JustFloat(object):
def __float__(self):
return flt_arg
class JustFloatOS:
def __float__(self):
return flt_arg
for f in self.test_functions:
# usual usage
self.cAssertAlmostEqual(f(MyComplex(cx_arg)), f(cx_arg))
self.cAssertAlmostEqual(f(MyComplexOS(cx_arg)), f(cx_arg))
# other combinations of __float__ and __complex__
self.cAssertAlmostEqual(f(FloatAndComplex()), f(cx_arg))
self.cAssertAlmostEqual(f(FloatAndComplexOS()), f(cx_arg))
self.cAssertAlmostEqual(f(JustFloat()), f(flt_arg))
self.cAssertAlmostEqual(f(JustFloatOS()), f(flt_arg))
# TypeError should be raised for classes not providing
# either __complex__ or __float__, even if they provide
# __int__, __long__ or __index__. An old-style class
# currently raises AttributeError instead of a TypeError;
# this could be considered a bug.
self.assertRaises(TypeError, f, NeitherComplexNorFloat())
self.assertRaises(TypeError, f, MyInt())
self.assertRaises(Exception, f, NeitherComplexNorFloatOS())
self.assertRaises(Exception, f, MyIntOS())
# non-complex return value from __complex__ -> TypeError
for bad_complex in non_complexes:
self.assertRaises(TypeError, f, MyComplex(bad_complex))
self.assertRaises(TypeError, f, MyComplexOS(bad_complex))
# exceptions in __complex__ should be propagated correctly
self.assertRaises(SomeException, f, MyComplexException())
self.assertRaises(SomeException, f, MyComplexExceptionOS())
def test_input_type(self):
# ints and longs should be acceptable inputs to all cmath
# functions, by virtue of providing a __float__ method
for f in self.test_functions:
for arg in [2, 2L, 2.]:
self.cAssertAlmostEqual(f(arg), f(arg.__float__()))
# but strings should give a TypeError
for f in self.test_functions:
for arg in ["a", "long_string", "0", "1j", ""]:
self.assertRaises(TypeError, f, arg)
def test_cmath_matches_math(self):
# check that corresponding cmath and math functions are equal
# for floats in the appropriate range
# test_values in (0, 1)
test_values = [0.01, 0.1, 0.2, 0.5, 0.9, 0.99]
# test_values for functions defined on [-1., 1.]
unit_interval = test_values + [-x for x in test_values] + \
[0., 1., -1.]
# test_values for log, log10, sqrt
positive = test_values + [1.] + [1./x for x in test_values]
nonnegative = [0.] + positive
# test_values for functions defined on the whole real line
real_line = [0.] + positive + [-x for x in positive]
test_functions = {
'acos' : unit_interval,
'asin' : unit_interval,
'atan' : real_line,
'cos' : real_line,
'cosh' : real_line,
'exp' : real_line,
'log' : positive,
'log10' : positive,
'sin' : real_line,
'sinh' : real_line,
'sqrt' : nonnegative,
'tan' : real_line,
'tanh' : real_line}
for fn, values in test_functions.items():
float_fn = getattr(math, fn)
complex_fn = getattr(cmath, fn)
for v in values:
self.cAssertAlmostEqual(float_fn(v), complex_fn(v))
# test two-argument version of log with various bases
for base in [0.5, 2., 10.]:
for v in positive:
self.cAssertAlmostEqual(cmath.log(v, base), math.log(v, base))
def test_main():
run_unittest(CMathTests)
if __name__ == "__main__":
test_main()

5
Misc/NEWS
View File

@ -12,6 +12,11 @@ What's New in Python 2.6 alpha 1?
Core and builtins
-----------------
- Patch #1675423: PyComplex_AsCComplex() now tries to convert an object
to complex using its __complex__() method before falling back to the
__float__() method. Therefore, the functions in the cmath module now
can operate on objects that define a __complex__() method.
- Patch #1623563: allow __class__ assignment for classes with __slots__.
The old and the new class are still required to have the same slot names.

49
Objects/complexobject.c
View File

@ -252,12 +252,59 @@ Py_complex
PyComplex_AsCComplex(PyObject *op)
{
Py_complex cv;
PyObject *newop = NULL;
static PyObject *complex_str = NULL;
assert(op);
/* If op is already of type PyComplex_Type, return its value */
if (PyComplex_Check(op)) {
return ((PyComplexObject *)op)->cval;
}
/* If not, use op's __complex__ method, if it exists */
/* return -1 on failure */
cv.real = -1.;
cv.imag = 0.;
if (PyInstance_Check(op)) {
/* this can go away in python 3000 */
if (PyObject_HasAttrString(op, "__complex__")) {
newop = PyObject_CallMethod(op, "__complex__", NULL);
if (!newop)
return cv;
}
/* else try __float__ */
} else {
PyObject *complexfunc;
if (!complex_str) {
if (!(complex_str = PyString_FromString("__complex__")))
return cv;
}
complexfunc = _PyType_Lookup(op->ob_type, complex_str);
/* complexfunc is a borrowed reference */
if (complexfunc) {
newop = PyObject_CallFunctionObjArgs(complexfunc, op, NULL);
if (!newop)
return cv;
}
}
if (newop) {
if (!PyComplex_Check(newop)) {
PyErr_SetString(PyExc_TypeError,
"__complex__ should return a complex object");
Py_DECREF(newop);
return cv;
}
cv = ((PyComplexObject *)newop)->cval;
Py_DECREF(newop);
return cv;
}
/* If neither of the above works, interpret op as a float giving the
real part of the result, and fill in the imaginary part as 0. */
else {
/* PyFloat_AsDouble will return -1 on failure */
cv.real = PyFloat_AsDouble(op);
cv.imag = 0.;
return cv;
}
}