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Change the semantics of "return" in generators, as discussed on the

Browse source 
Iterators list and Python-Dev; e.g., these all pass now:

def g1():
    try:
        return
    except:
        yield 1
assert list(g1()) == []

def g2():
    try:
        return
    finally:
        yield 1
assert list(g2()) == [1]

def g3():
    for i in range(3):
        yield None
    yield None
assert list(g3()) == [None] * 4

compile.c:  compile_funcdef and com_return_stmt:  Just van Rossum's patch
to compile the same code for "return" regardless of function type (this
goes back to the previous scheme of returning Py_None).

ceval.c:  gen_iternext:  take a return (but not a yield) of Py_None as
meaning the generator is exhausted.
This commit is contained in:
Tim Peters 2001-06-23 06:19:16 +00:00
parent be9d10edbb
commit ad1a18b78e
2 changed files with 17 additions and 25 deletions
Download patch file Download diff file Expand all files Collapse all files

7
Python/ceval.c
View file

@ -166,6 +166,13 @@ gen_iternext(genobject *gen)
Py_XDECREF(f->f_back);
f->f_back = NULL;
/* If the generator just returned (as opposed to yielding), signal
* that the generator is exhausted. */
if (result == Py_None && f->f_stacktop == NULL) {
Py_DECREF(result);
result = NULL;
}
return result;
}

35
Python/compile.c
View file

@ -2639,20 +2639,14 @@ com_return_stmt(struct compiling *c, node *n)
com_error(c, PyExc_SyntaxError,
"'return' with argument inside generator");
}
com_addoparg(c, LOAD_CONST,
com_addconst(c, PyExc_StopIteration));
}
if (NCH(n) < 2) {
com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
com_push(c, 1);
com_addoparg(c, RAISE_VARARGS, 1);
}
else {
if (NCH(n) < 2) {
com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
com_push(c, 1);
}
else
com_node(c, CHILD(n, 1));
com_addbyte(c, RETURN_VALUE);
}
else
com_node(c, CHILD(n, 1));
com_addbyte(c, RETURN_VALUE);
com_pop(c, 1);
}
@ -3711,19 +3705,10 @@ compile_funcdef(struct compiling *c, node *n)
c->c_infunction = 1;
com_node(c, CHILD(n, 4));
c->c_infunction = 0;
if (c->c_flags & CO_GENERATOR) {
com_addoparg(c, LOAD_CONST,
com_addconst(c, PyExc_StopIteration));
com_push(c, 1);
com_addoparg(c, RAISE_VARARGS, 1);
com_pop(c, 1);
}
else {
com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
com_push(c, 1);
com_addbyte(c, RETURN_VALUE);
com_pop(c, 1);
}
com_addoparg(c, LOAD_CONST, com_addconst(c, Py_None));
com_push(c, 1);
com_addbyte(c, RETURN_VALUE);
com_pop(c, 1);
}
static void