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authorFred Drake <fdrake@acm.org>1998-02-04 20:26:31 (GMT)
committerFred Drake <fdrake@acm.org>1998-02-04 20:26:31 (GMT)
commitb6e5032d9cf74668734e5590534e4541fcd5f041 (patch)
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Added description of "D" format for PyArg_ParseTuple(), including example
use with function name provided as well. Wrapped up PyArg_ParseTupleAndKeywords() description and provided example based on Geoff Philbrick's example to the mailing list.
Diffstat (limited to 'Doc/ext')
-rw-r--r--Doc/ext/ext.tex89
1 files changed, 86 insertions, 3 deletions
diff --git a/Doc/ext/ext.tex b/Doc/ext/ext.tex
index 22f7ebc..a462792 100644
--- a/Doc/ext/ext.tex
+++ b/Doc/ext/ext.tex
@@ -356,14 +356,17 @@ function. It should normally always be \samp{METH_VARARGS} or
\samp{METH_VARARGS | METH_KEYWORDS}; a value of \samp{0} means that an
obsolete variant of \code{PyArg_ParseTuple()} is used.
+When using only \samp{METH_VARARGS}, the function should expect
+the Python-level parameters to be passed in as a tuple acceptable for
+parsing via \cfunction{PyArg_ParseTuple()}; more information on this
+function is provided below.
+
The \code{METH_KEYWORDS} bit may be set in the third field if keyword
arguments should be passed to the function. In this case, the \C{}
function should accept a third \samp{PyObject *} parameter which will
be a dictionary of keywords. Use \code{PyArg_ParseTupleAndKeywords()}
to parse the arguemts to such a function.
-XXX --- need to explain PyArg_ParseTupleAndKeywords() in detail.
-
The method table must be passed to the interpreter in the module's
initialization function (which should be the only non-\code{static}
item defined in the module file):
@@ -621,6 +624,9 @@ Convert a Python floating point number to a \C{} \code{float}.
\item[\samp{d} (float) {[double]}]
Convert a Python floating point number to a \C{} \code{double}.
+\item[\samp{D} (complex) {[Py_complex]}]
+Convert a Python complex number to a \C{} \code{Py_complex} structure.
+
\item[\samp{O} (object) {[PyObject *]}]
Store a Python object (without any conversion) in a \C{} object pointer.
The \C{} program thus receives the actual object that was passed. The
@@ -736,8 +742,85 @@ Some example calls:
/* Possible Python call:
f(((0, 0), (400, 300)), (10, 10)) */
}
+
+ {
+ Py_complex c;
+ ok = PyArg_ParseTuple(args, "D:myfunction", &c);
+ /* a complex, also providing a function name for errors */
+ /* Possible Python call: myfunction(1+2j) */
+ }
\end{verbatim}
-%
+
+
+\section{Keyword Parsing with \sectcode{PyArg_ParseTupleAndKeywords()}}
+
+The \cfunction{PyArg_ParseTupleAndKeywords()} function is declared as
+follows:
+
+\bcode\begin{verbatim}
+ int PyArg_ParseTupleAndKeywords(PyObject *arg, PyObject *kwdict,
+ char *format, char **kwlist, ...);
+\end{verbatim}\ecode
+
+The \var{arg} and \var{format} parameters are identical to those of the
+\cfunction{PyArg_ParseTuple()} function. The \var{kwdict} parameter
+is the dictionary of keywords received as the third parameter from the
+Python runtime. The \var{kwlist} parameter is a \NULL{}-terminated
+list of strings which identify the parameters; the names are matched
+with the type information from \var{format} from left to right.
+
+\strong{Note:} Nested tuples cannot be parsed when using keyword
+arguments! Keyword parameters passed in which are not present in the
+\var{kwlist} will cause a \exception{TypeError} to be raised.
+
+Here is an example module which uses keywords, based on an example by
+Geoff Philbrick (\email{philbrick@hks.com}):
+
+\begin{verbatim}
+#include <stdio.h>
+#include "Python.h"
+
+static PyObject *
+keywdarg_parrot(self, args, keywds)
+ PyObject *self;
+ PyObject *args;
+ PyObject *keywds;
+{
+ int voltage;
+ char *state = "a stiff";
+ char *action = "voom";
+ char *type = "Norwegian Blue";
+
+ static char *kwlist[] = {"voltage", "state", "action", "type", NULL};
+
+ if (!PyArg_ParseTupleAndKeywords(args, keywds, "i|sss", kwlist,
+ &voltage, &state, &action, &type))
+ return NULL;
+
+ printf("-- This parrot wouldn't %s if you put %i Volts through it.\n",
+ action, voltage);
+ printf("-- Lovely plumage, the %s -- It's %s!\n", type, state);
+
+ Py_INCREF(Py_None);
+
+ return Py_None;
+}
+
+static PyMethodDef keywdarg_methods[] = {
+ {"parrot", (PyCFunction)keywdarg_parrot, METH_VARARGS|METH_KEYWORDS},
+ {NULL, NULL} /* sentinel */
+};
+
+void
+initkeywdarg()
+{
+ /* Create the module and add the functions */
+ Py_InitModule("keywdarg", keywdarg_methods);
+
+}
+\end{verbatim}
+
+
\section{The \sectcode{Py_BuildValue()} Function}
This function is the counterpart to \code{PyArg_ParseTuple()}. It is