traverseda
/
cpython
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Patch #1642844: comments to clarify the complexobject constructor.

This commit is contained in:
Georg Brandl 2007-03-13 07:57:51 +00:00
parent 0692a2621c
commit 8f032cbb05
1 changed files with 25 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
Objects/complexobject.c
View File

@ -857,12 +857,14 @@ complex_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
&r, &i))
return NULL;
/* Special-case for single argument that is already complex */
/* Special-case for a single argument when type(arg) is complex. */
if (PyComplex_CheckExact(r) && i == NULL &&
type == &PyComplex_Type) {
/* Note that we can't know whether it's safe to return
a complex *subclass* instance as-is, hence the restriction
to exact complexes here. */
to exact complexes here. If either the input or the
output is a complex subclass, it will be handled below
as a non-orthogonal vector. */
Py_INCREF(r);
return r;
}
@ -913,6 +915,14 @@ complex_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
}
return NULL;
}
/* If we get this far, then the "real" and "imag" parts should
both be treated as numbers, and the constructor should return a
complex number equal to (real + imag*1j).
Note that we do NOT assume the input to already be in canonical
form; the "real" and "imag" parts might themselves be complex
numbers, which slightly complicates the code below. */
if (PyComplex_Check(r)) {
/* Note that if r is of a complex subtype, we're only
retaining its real & imag parts here, and the return
@ -923,8 +933,14 @@ complex_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
}
}
else {
/* The "real" part really is entirely real, and contributes
nothing in the imaginary direction.
Just treat it as a double. */
cr.imag = 0.0;
tmp = PyNumber_Float(r);
if (own_r) {
/* r was a newly created complex number, rather
than the original "real" argument. */
Py_DECREF(r);
}
if (tmp == NULL)
@ -937,7 +953,6 @@ complex_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
}
cr.real = PyFloat_AsDouble(tmp);
Py_DECREF(tmp);
cr.imag = 0.0;
}
if (i == NULL) {
ci.real = 0.0;
@ -946,13 +961,19 @@ complex_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
else if (PyComplex_Check(i))
ci = ((PyComplexObject*)i)->cval;
else {
/* The "imag" part really is entirely imaginary, and
contributes nothing in the real direction.
Just treat it as a double. */
ci.imag = 0.0;
tmp = (*nbi->nb_float)(i);
if (tmp == NULL)
return NULL;
ci.real = PyFloat_AsDouble(tmp);
Py_DECREF(tmp);
ci.imag = 0.;
}
/* If the input was in canonical form, then the "real" and "imag"
parts are real numbers, so that ci.real and cr.imag are zero.
We need this correction in case they were not real numbers. */
cr.real -= ci.imag;
cr.imag += ci.real;
return complex_subtype_from_c_complex(type, cr);