Neal Norwitz wrote:
> This is an entire function from Python/ast.c.
> Sequences do not know what type they hold, so there needs to be
> different dealloc functions to free them properly (asdl_*_seq_free()).
Well, that's one complication that would go away if
the nodes were PyObjects.
> The memory leak occurs when FunctionDef fails. name, args, body, and
> decorator_seq are all local and would not be freed. The simple
> variables can be freed in each "constructor" like FunctionDef(), but
> the sequences cannot unless they keep the info about which type they
> hold.
If FunctionDef's reference semantics are defined so
that it steals references to its arguments, then here
is how the same function would look with PyObject
AST nodes, as far as I can see:
static PyObject *
ast_for_funcdef(struct compiling *c, const node *n)
{
/* funcdef: 'def' [decorators] NAME parameters ':' suite */
PyObject *name = NULL;
PyObject *args = NULL;
PyObject *body = NULL;
PyObject *decorator_seq = NULL;
int name_i;
REQ(n, funcdef);
if (NCH(n) == 6) { /* decorators are present */
decorator_seq = ast_for_decorators(c, CHILD(n, 0));
if (!decorator_seq)
goto error;
name_i = 2;
}
else {
name_i = 1;
}
name = NEW_IDENTIFIER(CHILD(n, name_i));
if (!name)
goto error;
else if (!strcmp(STR(CHILD(n, name_i)), "None")) {
ast_error(CHILD(n, name_i), "assignment to None");
goto error;
}
args = ast_for_arguments(c, CHILD(n, name_i + 1));
if (!args)
goto error;
body = ast_for_suite(c, CHILD(n, name_i + 3));
if (!body)
goto error;
return FunctionDef(name, args, body, decorator_seq, LINENO(n));
error:
Py_XDECREF(body);
Py_XDECREF(decorator_seq);
Py_XDECREF(args);
Py_XDECREF(name);
return NULL;
}
The only things I've changed are turning some type
declarations into PyObject * and replacing the
deallocation functions at the end with Py_XDECREF!
Maybe there are other functions where it would not
be so straightforward, but if this really is a
typical AST function, switching to PyObjects looks
like it wouldn't be difficult at all, and would
actually make some things simpler.
--
Greg Ewing, Computer Science Dept, +--------------------------------------+
University of Canterbury, | A citizen of NewZealandCorp, a |
Christchurch, New Zealand | wholly-owned subsidiary of USA Inc. |
[EMAIL PROTECTED] +--------------------------------------+
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