Metadata-Version: 2.1
Name: pure-protobuf
Version: 2.0.1
Summary: Python implementation of Protocol Buffers data types with dataclasses support
Home-page: https://github.com/eigenein/protobuf
Author: Pavel Perestoronin
Author-email: eigenein@gmail.com
License: UNKNOWN
Project-URL: Changelog, https://github.com/eigenein/protobuf/blob/master/CHANGELOG.md
Description: # `pure-protobuf`
        
        Python implementation of [Protocol Buffers](http://code.google.com/apis/protocolbuffers/docs/encoding.html) data types.
        
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        ## Dataclasses
        
        `pure-protobuf` allows you to take advantages of the standard [`dataclasses`](https://docs.python.org/3/library/dataclasses.html) module to define message types. It is preferred over the legacy interface for new projects. The dataclasses interface is available in Python 3.6 and higher.
        
        The legacy interface is deprecated and still available via `pure_protobuf.legacy`.
        
        This guide describes how to use `pure-protobuf` to structure your data. It tries to follow [the standard developer guide](https://developers.google.com/protocol-buffers/docs/proto3). It also assumes that you're familiar with Protocol Buffers.
        
        ### Defining a message type
        
        Let's look at [the simple example](https://developers.google.com/protocol-buffers/docs/proto3#simple). Here's how it looks like in `proto3` syntax:
        
        ```proto
        syntax = "proto3";
        
        message SearchRequest {
          string query = 1;
          int32 page_number = 2;
          int32 result_per_page = 3;
        }
        ```
        
        And this is how you define it with `pure-protobuf`:
        
        ```python
        from dataclasses import dataclass
        
        from pure_protobuf.dataclasses_ import field, message
        from pure_protobuf.types import int32
        
        
        @message
        @dataclass
        class SearchRequest:
            query: str = field(1, default='')
            page_number: int32 = field(2, default=int32(0))
            result_per_page: int32 = field(3, default=int32(0))
           
        
        assert SearchRequest(
            query='hello',
            page_number=int32(1),
            result_per_page=int32(10),
        ).dumps() == b'\x0A\x05hello\x10\x01\x18\x0A'
        ```
        
        Keep in mind that `@message` decorator **must** stay on top of [`@dataclass`](https://docs.python.org/3/library/dataclasses.html#dataclasses.dataclass).
        
        ### Serializing
        
        Each class wrapped with `@message` gets two methods attached:
        - `dumps() -> bytes` to serialize message into a byte string
        - `dump(io: IO)` to serialize message into a file-like object
        
        ### Deserializing
        
        Each classes wrapped with `@message` gets two class methods attached:
        - `loads(bytes_: bytes) -> TMessage` to deserialize a message from a byte string
        - `load(io: IO) -> TMessage` to deserialize a message from a file-like object
        
        These methods are also available as standalone functions in `pure_protobuf.dataclasses_`:
        - `load(cls: Type[T], io: IO) -> T`
        - `loads(cls: Type[T], bytes_: bytes) -> T`
        
        ### Specifying field types
        
        In `pure-protobuf` types are specified with [type hints](https://www.python.org/dev/peps/pep-0484/). Native Python `float`, `str`, `bytes` and `bool` types are supported. Since other Protocol Buffers types don't exist as native Python types, the package uses [`NewType`](https://docs.python.org/3/library/typing.html#newtype) to define them. They're available via `pure_protobuf.types` and named in the same way.
        
        ### Assigning field numbers
        
        Field numbers are provided via the `metadata` parameter of the [`field`](https://docs.python.org/3/library/dataclasses.html#dataclasses.field) function: `field(..., metadata={'number': number})`. However, to improve readability and save some characters, `pure-protobuf` provides a helper function `pure_protobuf.dataclasses_.field` which accepts field number as the first positional parameter and just passes it to the standard `field` function.
        
        ### Specifying field rules
        
        [`typing.List`](https://docs.python.org/3/library/typing.html#typing.List) and [`typing.Iterable`](https://docs.python.org/3/library/typing.html#typing.Iterable) annotations are automatically converted to [repeated fields](https://developers.google.com/protocol-buffers/docs/proto3#specifying-field-rules). Repeated fields of scalar numeric types use packed encoding by default:
        
        ```python
        from dataclasses import dataclass
        from typing import List
        
        from pure_protobuf.dataclasses_ import field, message
        from pure_protobuf.types import int32
        
        
        @message
        @dataclass
        class Message:
            foo: List[int32] = field(1, default_factory=list)
        ```
        
        It's also possible to wrap a field type with [`typing.Optional`](https://docs.python.org/3/library/typing.html#typing.Optional). If `None` is assigned to an `Optional` field, then the field will be skipped during serialization.
        
        ### Default values
        
        In `pure-protobuf` it's developer's responsibility to take care of default values. If encoded message does not contain a particular element, the corresponding field stays unassigned. It means that the standard `default` and `default_factory` parameters of the `field` function work as usual:
        
        ```python
        from dataclasses import dataclass
        from typing import Optional
        
        from pure_protobuf.dataclasses_ import field, message
        from pure_protobuf.types import int32
        
        
        @message
        @dataclass
        class Foo:
            bar: int32 = field(1, default=42)
            qux: Optional[int32] = field(2, default=None)
        
        
        assert Foo().dumps() == b'\x08\x2A'
        assert Foo.loads(b'') == Foo(bar=42)
        ```
        
        In fact, the pattern `qux: Optional[int32] = field(2, default=None)` is so common that there's a convenience function `optional_field` to define an `Optional` field with `None` value by default:
        
        ```python
        from dataclasses import dataclass
        from typing import Optional
        
        from pure_protobuf.dataclasses_ import optional_field, message
        from pure_protobuf.types import int32
        
        
        @message
        @dataclass
        class Foo:
            qux: Optional[int32] = optional_field(2)
        
        
        assert Foo().dumps() == b''
        assert Foo.loads(b'') == Foo(qux=None)
        ```
        
        ### Enumerations
        
        Subclasses of the standard [`IntEnum`](https://docs.python.org/3/library/enum.html#intenum) class are supported:
        
        ```python
        from dataclasses import dataclass
        from enum import IntEnum
        
        from pure_protobuf.dataclasses_ import field, message
        
        
        class TestEnum(IntEnum):
            BAR = 1
        
        
        @message
        @dataclass
        class Test:
            foo: TestEnum = field(1)
        
        
        assert Test(foo=TestEnum.BAR).dumps() == b'\x08\x01'
        assert Test.loads(b'\x08\x01') == Test(foo=TestEnum.BAR)
        ```
        
        ### Using other message types
        
        Embedded messages are defined the same way as normal dataclasses:
        
        ```python
        from dataclasses import dataclass
        
        from pure_protobuf.dataclasses_ import field, message
        from pure_protobuf.types import int32
        
        
        @message
        @dataclass
        class Test1:
            a: int32 = field(1, default=0)
        
        
        @message
        @dataclass
        class Test3:
            c: Test1 = field(3, default_factory=Test1)
        
        
        assert Test3(c=Test1(a=int32(150))).dumps() == b'\x1A\x03\x08\x96\x01'
        ```
        
        ### Well-known message types
        
        `pure_protobuf.google` also provides built-in definitions for the following [well-known message types](https://developers.google.com/protocol-buffers/docs/reference/google.protobuf):
        
        | Annotation   | `pure_protobuf.types.google` | `.proto`    |
        | ------------ | ---------------------------- | ----------- |
        | `datetime`   | `Timestamp`                  | `Timestamp` |
        | `timedelta`  | `Duration`                   | `Duration`  |
        | `typing.Any` | `Any_`                       | `Any`       |
        
        They're handled automatically, you have nothing to do but use them normally in type hints:
        
        ```python
        from dataclasses import dataclass
        from datetime import datetime
        from typing import Optional
        
        from pure_protobuf.dataclasses_ import field, message
        
        
        @message
        @dataclass
        class Test:
            timestamp: Optional[datetime] = field(1, default=None)
        ```
        
        #### [`Any`](https://developers.google.com/protocol-buffers/docs/proto3#any)
        
        Since `pure-protobuf` is not able to download or parse `.proto` definitions, it provides a limited implementation of the [`Any`](https://developers.google.com/protocol-buffers/docs/proto3#any) message type. That is, you still have to define all message classes in the usual way. Then, `pure-protobuf` will be able to import and instantiate an encoded value:
        
        ```python
        from dataclasses import dataclass
        from typing import Any, Optional
        
        from pure_protobuf.dataclasses_ import field, message
        from pure_protobuf.types.google import Timestamp
        
        
        @message
        @dataclass
        class Message:
            value: Optional[Any] = field(1)
        
        
        # Here `Timestamp` is used just as an example, in principle any importable user type works.
        message = Message(value=Timestamp(seconds=42))
        assert Message.loads(message.dumps()) == message
        ```
        
Platform: UNKNOWN
Classifier: Development Status :: 5 - Production/Stable
Classifier: Intended Audience :: Developers
Classifier: Operating System :: OS Independent
Classifier: Topic :: Software Development :: Libraries
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Classifier: Programming Language :: Python :: 3 :: Only
Classifier: Programming Language :: Python :: 3.6
Classifier: Programming Language :: Python :: 3.7
Classifier: Programming Language :: Python :: 3.8
Classifier: License :: OSI Approved :: MIT License
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