Avoid attr("__repr__") in initialize_generic (#2317)

If the default argument value is a class, and not an instance of a
class, `a.value.attr("__repr__")` raises a `ValueError`. Switching to
`repr(a.value)` makes this use case work.

Fixes #2028
This commit is contained in:
Boris Staletic 2020-07-24 18:43:59 +02:00 committed by GitHub
parent 6f3e5e38c9
commit 2819ce64a4
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3 changed files with 8 additions and 1 deletions

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@ -228,7 +228,7 @@ protected:
if (a.descr)
a.descr = strdup(a.descr);
else if (a.value)
a.descr = strdup(a.value.attr("__repr__")().cast<std::string>().c_str());
a.descr = strdup(repr(a.value).cast<std::string>().c_str());
}
rec->is_constructor = !strcmp(rec->name, "__init__") || !strcmp(rec->name, "__setstate__");

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@ -123,4 +123,9 @@ TEST_SUBMODULE(kwargs_and_defaults, m) {
py::class_<KWClass>(m, "KWClass")
.def("foo0", &KWClass::foo)
.def("foo1", &KWClass::foo, "x"_a, "y"_a);
// Make sure a class (not an instance) can be used as a default argument.
// The return value doesn't matter, only that the module is importable.
m.def("class_default_argument", [](py::object a) { return py::repr(a); },
"a"_a = py::module::import("decimal").attr("Decimal"));
}

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@ -191,3 +191,5 @@ def test_args_refcount():
# tuple without having to inc_ref the individual elements, but here we can't, hence the extra
# refs.
assert m.mixed_args_refcount(myval, myval, myval) == (exp3 + 3, exp3 + 3, exp3 + 3)
assert m.class_default_argument() == "<class 'decimal.Decimal'>"