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Add enum value to enum repr #2126

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Merged
merged 1 commit into from
Sep 19, 2020
Merged

Add enum value to enum repr #2126

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34 changes: 18 additions & 16 deletions include/pybind11/pybind11.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1486,6 +1486,16 @@ detail::initimpl::pickle_factory<GetState, SetState> pickle(GetState &&g, SetSta
}

PYBIND11_NAMESPACE_BEGIN(detail)

inline str enum_name(handle arg) {
dict entries = arg.get_type().attr("__entries");
for (const auto &kv : entries) {
if (handle(kv.second[int_(0)]).equal(arg))
return pybind11::str(kv.first);
}
return "???";
}

struct enum_base {
enum_base(handle base, handle parent) : m_base(base), m_parent(parent) { }

Expand All @@ -1495,29 +1505,21 @@ struct enum_base {
auto static_property = handle((PyObject *) get_internals().static_property_type);

m_base.attr("__repr__") = cpp_function(
[](handle arg) -> str {
[](object arg) -> str {
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Why handle to object? You don't need reference counting here, do you?

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Argh, good catch. I should've look more closely at the details rather than eyeballing the structural changes and shrugging "OK"...

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OK, so I just tried this out, and the reason seems to be because there's no int_ conversion from handle (you can reinterpret_steal/reinterpret_borrow, but those will not do the int(...) conversion).

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See e.g. __getstate__ and __hash__, also doing that. I don't immediately see a better solution, then? (though if feels there ought to be one, changing the interface of the Python types; but that's a different discussion/PR)

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Maybe pass the object by reference, to avoid reference counting?

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@bstaletic Hmmm, interesting.

Thinking about it a bit futher: will it, though? I believe (though the cast, make_caster, cast_op, PYBIND11_TYPE_CASTER, ... code is quite convoluted) that the object will be created and moved from the caster anyway, if you take it by value. So it shouldn't matter?

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I vote to keep it this way, merge this PR, and create an issue/discussion on why you can't call the int_ conversion on a handle (like you can for str).

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I'm okay with that.

handle type = type::handle_of(arg);
object type_name = type.attr("__name__");
dict entries = type.attr("__entries");
for (auto kv : entries) {
object other = kv.second[int_(0)];
if (other.equal(arg))
return pybind11::str("{}.{}").format(type_name, kv.first);
}
return pybind11::str("{}.???").format(type_name);
return pybind11::str("<{}.{}: {}>").format(type_name, enum_name(arg), int_(arg));
}, name("__repr__"), is_method(m_base)
);

m_base.attr("name") = property(cpp_function(
m_base.attr("name") = property(cpp_function(&enum_name, name("name"), is_method(m_base)));

m_base.attr("__str__") = cpp_function(
[](handle arg) -> str {
dict entries = type::handle_of(arg).attr("__entries");
for (auto kv : entries) {
if (handle(kv.second[int_(0)]).equal(arg))
return pybind11::str(kv.first);
}
return "???";
object type_name = type::handle_of(arg).attr("__name__");
return pybind11::str("{}.{}").format(type_name, enum_name(arg));
}, name("name"), is_method(m_base)
));
);

m_base.attr("__doc__") = static_property(cpp_function(
[](handle arg) -> std::string {
Expand Down
7 changes: 6 additions & 1 deletion tests/test_enum.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,9 @@ def test_unscoped_enum():
assert str(m.UnscopedEnum.EOne) == "UnscopedEnum.EOne"
assert str(m.UnscopedEnum.ETwo) == "UnscopedEnum.ETwo"
assert str(m.EOne) == "UnscopedEnum.EOne"
assert repr(m.UnscopedEnum.EOne) == "<UnscopedEnum.EOne: 1>"
assert repr(m.UnscopedEnum.ETwo) == "<UnscopedEnum.ETwo: 2>"
assert repr(m.EOne) == "<UnscopedEnum.EOne: 1>"

# name property
assert m.UnscopedEnum.EOne.name == "EOne"
Expand Down Expand Up @@ -143,6 +146,8 @@ def test_scoped_enum():
def test_implicit_conversion():
assert str(m.ClassWithUnscopedEnum.EMode.EFirstMode) == "EMode.EFirstMode"
assert str(m.ClassWithUnscopedEnum.EFirstMode) == "EMode.EFirstMode"
assert repr(m.ClassWithUnscopedEnum.EMode.EFirstMode) == "<EMode.EFirstMode: 1>"
assert repr(m.ClassWithUnscopedEnum.EFirstMode) == "<EMode.EFirstMode: 1>"

f = m.ClassWithUnscopedEnum.test_function
first = m.ClassWithUnscopedEnum.EFirstMode
Expand All @@ -167,7 +172,7 @@ def test_implicit_conversion():
x[f(first)] = 3
x[f(second)] = 4
# Hashing test
assert str(x) == "{EMode.EFirstMode: 3, EMode.ESecondMode: 4}"
assert repr(x) == "{<EMode.EFirstMode: 1>: 3, <EMode.ESecondMode: 2>: 4}"


def test_binary_operators():
Expand Down