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OpenEnum
: an enum to represent protobuf's enumeration field values
#1079
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The wrapper to represent field of enumerated types with the possibility of unknown values.
Replace i32 with the type-checked wrapper.
Please add a description that explains your proposed change. That will make reviewing easier. |
Forgot to re-enable tempdir cleanup disabled for debugging.
Do you think that this logic could be applied to the oneof field ? |
I believe it works differently for oneofs: if an unknown field number is encountered in a message and it's not a known oneof variant or a regular field, the field is ignored. So the oneof field that would get the value if the variant field were described in the proto would get |
Will this break compatibility with proto2/closed enums? Personally, I don't use proto2, so I am not sure whether it is properly supported at all. |
I think it makes sense to provide a migration guide. |
What is the error message for a |
I would like to see some tests for |
self.#ident.get(#take_ref key).cloned().and_then(|x| { x.known() }) | ||
} | ||
#[doc=#insert_doc] | ||
pub fn #insert(&mut self, key: #key_ty, value: #ty) -> ::core::option::Option<#ty> { | ||
self.#ident.insert(key, value as i32).and_then(|x| { | ||
let result: ::core::result::Result<#ty, _> = ::core::convert::TryFrom::try_from(x); | ||
result.ok() | ||
}) | ||
self.#ident.insert(key, value.into()).and_then(|x| { x.known() }) |
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Is it beneficial to provide a get
and insert
function with the new wrapper? I feel like the map can be used directly with the helper functions provided by OpenEnum.
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As can be seen in the generated code itself, these methods provide considerable convenience for the most common use cases.
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Perhaps the insert method could be changed to return the possible old value as Option<OpenEnum<#ty>>
so the caller can choose the fallback behavior for unknown values, but that API would be inconsistent with the get method. If it's to be changed so, the only added convenience there would be the .into()
conversion call.
pub fn #get(&self) -> #ty { | ||
::core::convert::TryFrom::try_from(self.#ident).unwrap_or(#default) | ||
self.#ident.unwrap_or(#default) | ||
} | ||
|
||
#[doc=#set_doc] | ||
pub fn #set(&mut self, value: #ty) { | ||
self.#ident = value as i32; | ||
self.#ident = value.into(); | ||
} |
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Is it still beneficial to provide a get
, set
and push
functions with the new wrapper? I feel like the field can be used directly with the helper functions provided by OpenEnum.
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There is some convenience in the setter method:
msg.set_kind(Kind::Foo)
is nicer and more type-ahead friendly than
msg.kind = Kind::Foo.into()
The same applies to the push method for repeated fields.
The getter hides a bit much opinionated behavior, in my opinion, so it might be better to leave it to OpenEnum
helper methods to explicitly decide on how unknown values should be treated.
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Another thing to consider here is porting the existing code. If these methods get used instead of direct access to fields, which I assume happens a lot now because the fields are just i32
or Option<i32>
, updating to the version that generates OpenEnum
would not require changes.
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I think the better API is to have some sort of set
operation on OpenEnum
. Maybe something like:
msg.kind.set(Kind::Foo)
Well, this change will break existing code in many ways, so I think we should directly go for the best API
@@ -555,13 +550,13 @@ impl Ty { | |||
Ty::Bool => quote!(bool), | |||
Ty::String => quote!(&str), | |||
Ty::Bytes(..) => quote!(&[u8]), | |||
Ty::Enumeration(..) => quote!(i32), | |||
Ty::Enumeration(..) => unreachable!("an enum should never be queried for its ref type"), |
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Can you explain me why it should never be queried by ref?
} | ||
} | ||
|
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pub fn module(&self) -> Ident { | ||
match *self { | ||
Ty::Enumeration(..) => Ident::new("int32", Span::call_site()), | ||
Ty::Enumeration(..) => Ident::new("enumeration", Span::call_site()), |
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Does it make sense to use self.as_str()
for enumerations as well?
for value in values { | ||
encode(tag, value, buf); | ||
} |
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Could int32::encode_repeated
be reused here?
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No, unless int32::encode_repeated
is generalized to take an impl IntoIterator
that produces i32
. Which might be a good idea.
if values.is_empty() { | ||
return; | ||
} | ||
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encode_key(tag, WireType::LengthDelimited, buf); | ||
let len: usize = values | ||
.iter() | ||
.map(|value| encoded_len_varint(value.to_raw() as u64)) | ||
.sum(); | ||
encode_varint(len as u64, buf); | ||
|
||
for value in values { | ||
encode_varint(value.to_raw() as u64, buf); | ||
} |
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Could int32::encode_packed
be reused here?
if wire_type == WireType::LengthDelimited { | ||
// Packed. | ||
merge_loop(values, buf, ctx, |values, buf, ctx| { | ||
let mut value = Default::default(); | ||
merge(WireType::Varint, &mut value, buf, ctx)?; | ||
values.push(value); | ||
Ok(()) | ||
}) | ||
} else { | ||
// Unpacked. | ||
check_wire_type(WireType::Varint, wire_type)?; | ||
let mut value = Default::default(); | ||
merge(wire_type, &mut value, buf, ctx)?; | ||
values.push(value); | ||
Ok(()) | ||
} |
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Could int32::merge_repeated
be reused here?
key_len(tag) * values.len() | ||
+ values | ||
.iter() | ||
.map(|value| encoded_len_varint(value.to_raw() as u64)) | ||
.sum::<usize>() |
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Could int32::encoded_len_repeated
be reused here?
if values.is_empty() { | ||
0 | ||
} else { | ||
let len = values | ||
.iter() | ||
.map(|value| encoded_len_varint(value.to_raw() as u64)) | ||
.sum::<usize>(); | ||
key_len(tag) + encoded_len_varint(len as u64) + len | ||
} |
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Could int32::encoded_len_packed
be reused here?
let mut raw = 0; | ||
<i32 as Message>::merge_field(&mut raw, tag, wire_type, buf, ctx)?; | ||
*self = OpenEnum::from_raw(raw); | ||
Ok(()) |
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This is the same function as encoding::enumeration::merge
, right?
I believe prost has never been conformant with closed enums: the raw values have been left in the message as is.
I prefer option 2, even though it requires more work. Protobuf edition 2023 has closed enums as a feature, so they need to be supported even if we ignore proto2. |
What would be a good place for it? I can add a section to the README. |
I'm going to add at least one good example/doctest on the type. |
Have thought some more about this PR: I don't want to break users in this way. At least not now. I suggest making this an option in Once we feel good about the new API, we can think about changing the default. Please look at bytes for a good example of changing the generated data type. |
Instead of introducing a new type, a simple |
It's weird to have a Another benefit of introducing a new type is for the add-on macros and code generators that derive something on structs generated by prost-build. These could deal with the |
How are default values handles in this solution? Especially default values set for a specific field in the proto file. |
Another solution for #276, amenable to destructuring.
This changes the representation of enum fields in message structs to this generic wrapper, parameterized over the generated known enum type:
In an improvement over #1061, this allows convenient matching of enum field values as part of the message. There are also convenience methods to fallibly extract the known value in an
Option
orResult
.