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This commit significantly improves the developer experience for the Python Object-Based API by overhauling the generated `__init__` method for `T`-suffixed classes.
Previously, `T` objects had to be instantiated with an empty constructor, and their fields had to be populated manually one by one. This was verbose and not idiomatic Python.
This change modifies the Python code generator (`GenInitialize`) to produce `__init__` methods that are:
1. **Keyword-Argument-Friendly**: The constructor now accepts all table/struct fields as keyword arguments, allowing for concise, single-line object creation.
2. **Fully Typed**: The signature of the `__init__` method is now annotated with Python type hints. This provides immediate benefits for static analysis tools (like Mypy) and IDEs, enabling better autocompletion and type checking.
3. **Correctly Optional**: The generator now correctly wraps types in `Optional[...]` if their default value is `None`. This applies to strings, vectors, and other nullable fields, ensuring strict type safety.
The new approach remains **fully backward-compatible**, as all arguments have default values. Existing code that uses the empty constructor will continue to work without modification.
#### Example of a Generated `__init__`
**Before:**
```python
class KeyValueT(object):
def __init__(self):
self.key = None # type: str
self.value = None # type: str
```
**After:**
```python
class KeyValueT(object):
def __init__(self, key: Optional[str] = None, value: Optional[str] = None):
self.key = key
self.value = value
```
#### Example of User Code
**Before:**
```python
# Old, verbose way
kv = KeyValueT()
kv.key = "instrument"
kv.value = "EUR/USD"
```
**After:**
```python
# New, Pythonic way
kv = KeyValueT(key="instrument", value="EUR/USD")
```
190 lines
5.4 KiB
Python
190 lines
5.4 KiB
Python
# automatically generated by the FlatBuffers compiler, do not modify
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# namespace: NestedUnion
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import flatbuffers
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from flatbuffers.compat import import_numpy
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from typing import Any
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from MyGame.Example.NestedUnion.Test import Test
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from typing import Optional
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np = import_numpy()
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class Vec3(object):
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__slots__ = ['_tab']
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@classmethod
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def GetRootAs(cls, buf, offset: int = 0):
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n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, offset)
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x = Vec3()
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x.Init(buf, n + offset)
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return x
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@classmethod
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def GetRootAsVec3(cls, buf, offset=0):
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"""This method is deprecated. Please switch to GetRootAs."""
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return cls.GetRootAs(buf, offset)
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# Vec3
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def Init(self, buf: bytes, pos: int):
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self._tab = flatbuffers.table.Table(buf, pos)
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# Vec3
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def X(self):
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o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(4))
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if o != 0:
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return self._tab.Get(flatbuffers.number_types.Float64Flags, o + self._tab.Pos)
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return 0.0
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# Vec3
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def Y(self):
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o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(6))
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if o != 0:
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return self._tab.Get(flatbuffers.number_types.Float64Flags, o + self._tab.Pos)
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return 0.0
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# Vec3
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def Z(self):
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o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(8))
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if o != 0:
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return self._tab.Get(flatbuffers.number_types.Float64Flags, o + self._tab.Pos)
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return 0.0
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# Vec3
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def Test1(self):
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o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(10))
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if o != 0:
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return self._tab.Get(flatbuffers.number_types.Float64Flags, o + self._tab.Pos)
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return 0.0
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# Vec3
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def Test2(self):
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o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(12))
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if o != 0:
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return self._tab.Get(flatbuffers.number_types.Uint8Flags, o + self._tab.Pos)
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return 0
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# Vec3
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def Test3(self) -> Optional[Test]:
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o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(14))
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if o != 0:
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x = o + self._tab.Pos
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obj = Test()
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obj.Init(self._tab.Bytes, x)
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return obj
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return None
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def Vec3Start(builder: flatbuffers.Builder):
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builder.StartObject(6)
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def Start(builder: flatbuffers.Builder):
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Vec3Start(builder)
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def Vec3AddX(builder: flatbuffers.Builder, x: float):
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builder.PrependFloat64Slot(0, x, 0.0)
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def AddX(builder: flatbuffers.Builder, x: float):
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Vec3AddX(builder, x)
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def Vec3AddY(builder: flatbuffers.Builder, y: float):
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builder.PrependFloat64Slot(1, y, 0.0)
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def AddY(builder: flatbuffers.Builder, y: float):
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Vec3AddY(builder, y)
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def Vec3AddZ(builder: flatbuffers.Builder, z: float):
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builder.PrependFloat64Slot(2, z, 0.0)
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def AddZ(builder: flatbuffers.Builder, z: float):
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Vec3AddZ(builder, z)
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def Vec3AddTest1(builder: flatbuffers.Builder, test1: float):
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builder.PrependFloat64Slot(3, test1, 0.0)
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def AddTest1(builder: flatbuffers.Builder, test1: float):
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Vec3AddTest1(builder, test1)
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def Vec3AddTest2(builder: flatbuffers.Builder, test2: int):
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builder.PrependUint8Slot(4, test2, 0)
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def AddTest2(builder: flatbuffers.Builder, test2: int):
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Vec3AddTest2(builder, test2)
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def Vec3AddTest3(builder: flatbuffers.Builder, test3: Any):
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builder.PrependStructSlot(5, flatbuffers.number_types.UOffsetTFlags.py_type(test3), 0)
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def AddTest3(builder: flatbuffers.Builder, test3: Any):
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Vec3AddTest3(builder, test3)
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def Vec3End(builder: flatbuffers.Builder) -> int:
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return builder.EndObject()
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def End(builder: flatbuffers.Builder) -> int:
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return Vec3End(builder)
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import MyGame.Example.NestedUnion.Test
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try:
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from typing import Optional
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except:
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pass
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class Vec3T(object):
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# Vec3T
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def __init__(
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self,
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x = 0.0,
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y = 0.0,
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z = 0.0,
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test1 = 0.0,
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test2 = 0,
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test3 = None,
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):
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self.x = x # type: float
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self.y = y # type: float
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self.z = z # type: float
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self.test1 = test1 # type: float
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self.test2 = test2 # type: int
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self.test3 = test3 # type: Optional[MyGame.Example.NestedUnion.Test.TestT]
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@classmethod
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def InitFromBuf(cls, buf, pos):
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vec3 = Vec3()
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vec3.Init(buf, pos)
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return cls.InitFromObj(vec3)
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@classmethod
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def InitFromPackedBuf(cls, buf, pos=0):
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n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, pos)
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return cls.InitFromBuf(buf, pos+n)
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@classmethod
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def InitFromObj(cls, vec3):
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x = Vec3T()
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x._UnPack(vec3)
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return x
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# Vec3T
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def _UnPack(self, vec3):
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if vec3 is None:
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return
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self.x = vec3.X()
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self.y = vec3.Y()
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self.z = vec3.Z()
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self.test1 = vec3.Test1()
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self.test2 = vec3.Test2()
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if vec3.Test3() is not None:
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self.test3 = MyGame.Example.NestedUnion.Test.TestT.InitFromObj(vec3.Test3())
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# Vec3T
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def Pack(self, builder):
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Vec3Start(builder)
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Vec3AddX(builder, self.x)
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Vec3AddY(builder, self.y)
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Vec3AddZ(builder, self.z)
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Vec3AddTest1(builder, self.test1)
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Vec3AddTest2(builder, self.test2)
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if self.test3 is not None:
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test3 = self.test3.Pack(builder)
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Vec3AddTest3(builder, test3)
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vec3 = Vec3End(builder)
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return vec3
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