Files
flatbuffers-bigfoot/tests/MyGame/Example/NestedUnion/NestedUnionTest.py
Łukasz Kurowski c526cb640b [Python] Enhance object API __init__ with typed keyword arguments (#8615)
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")
```
2025-07-22 23:57:39 -07:00

162 lines
5.3 KiB
Python

# automatically generated by the FlatBuffers compiler, do not modify
# namespace: NestedUnion
import flatbuffers
from flatbuffers.compat import import_numpy
from typing import Any
from flatbuffers.table import Table
from typing import Optional
np = import_numpy()
class NestedUnionTest(object):
__slots__ = ['_tab']
@classmethod
def GetRootAs(cls, buf, offset: int = 0):
n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, offset)
x = NestedUnionTest()
x.Init(buf, n + offset)
return x
@classmethod
def GetRootAsNestedUnionTest(cls, buf, offset=0):
"""This method is deprecated. Please switch to GetRootAs."""
return cls.GetRootAs(buf, offset)
# NestedUnionTest
def Init(self, buf: bytes, pos: int):
self._tab = flatbuffers.table.Table(buf, pos)
# NestedUnionTest
def Name(self) -> Optional[str]:
o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(4))
if o != 0:
return self._tab.String(o + self._tab.Pos)
return None
# NestedUnionTest
def DataType(self):
o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(6))
if o != 0:
return self._tab.Get(flatbuffers.number_types.Uint8Flags, o + self._tab.Pos)
return 0
# NestedUnionTest
def Data(self) -> Optional[flatbuffers.table.Table]:
o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(8))
if o != 0:
obj = Table(bytearray(), 0)
self._tab.Union(obj, o)
return obj
return None
# NestedUnionTest
def Id(self):
o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(10))
if o != 0:
return self._tab.Get(flatbuffers.number_types.Int16Flags, o + self._tab.Pos)
return 0
def NestedUnionTestStart(builder: flatbuffers.Builder):
builder.StartObject(4)
def Start(builder: flatbuffers.Builder):
NestedUnionTestStart(builder)
def NestedUnionTestAddName(builder: flatbuffers.Builder, name: int):
builder.PrependUOffsetTRelativeSlot(0, flatbuffers.number_types.UOffsetTFlags.py_type(name), 0)
def AddName(builder: flatbuffers.Builder, name: int):
NestedUnionTestAddName(builder, name)
def NestedUnionTestAddDataType(builder: flatbuffers.Builder, dataType: int):
builder.PrependUint8Slot(1, dataType, 0)
def AddDataType(builder: flatbuffers.Builder, dataType: int):
NestedUnionTestAddDataType(builder, dataType)
def NestedUnionTestAddData(builder: flatbuffers.Builder, data: int):
builder.PrependUOffsetTRelativeSlot(2, flatbuffers.number_types.UOffsetTFlags.py_type(data), 0)
def AddData(builder: flatbuffers.Builder, data: int):
NestedUnionTestAddData(builder, data)
def NestedUnionTestAddId(builder: flatbuffers.Builder, id: int):
builder.PrependInt16Slot(3, id, 0)
def AddId(builder: flatbuffers.Builder, id: int):
NestedUnionTestAddId(builder, id)
def NestedUnionTestEnd(builder: flatbuffers.Builder) -> int:
return builder.EndObject()
def End(builder: flatbuffers.Builder) -> int:
return NestedUnionTestEnd(builder)
import MyGame.Example.NestedUnion.Any
import MyGame.Example.NestedUnion.TestSimpleTableWithEnum
import MyGame.Example.NestedUnion.Vec3
try:
from typing import Union
except:
pass
class NestedUnionTestT(object):
# NestedUnionTestT
def __init__(
self,
name = None,
dataType = 0,
data = None,
id = 0,
):
self.name = name # type: Optional[str]
self.dataType = dataType # type: int
self.data = data # type: Union[None, 'MyGame.Example.NestedUnion.Vec3.Vec3T', 'MyGame.Example.NestedUnion.TestSimpleTableWithEnum.TestSimpleTableWithEnumT']
self.id = id # type: int
@classmethod
def InitFromBuf(cls, buf, pos):
nestedUnionTest = NestedUnionTest()
nestedUnionTest.Init(buf, pos)
return cls.InitFromObj(nestedUnionTest)
@classmethod
def InitFromPackedBuf(cls, buf, pos=0):
n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, pos)
return cls.InitFromBuf(buf, pos+n)
@classmethod
def InitFromObj(cls, nestedUnionTest):
x = NestedUnionTestT()
x._UnPack(nestedUnionTest)
return x
# NestedUnionTestT
def _UnPack(self, nestedUnionTest):
if nestedUnionTest is None:
return
self.name = nestedUnionTest.Name()
if self.name is not None:
self.name = self.name.decode('utf-8')
self.dataType = nestedUnionTest.DataType()
self.data = MyGame.Example.NestedUnion.Any.AnyCreator(self.dataType, nestedUnionTest.Data())
self.id = nestedUnionTest.Id()
# NestedUnionTestT
def Pack(self, builder):
if self.name is not None:
name = builder.CreateString(self.name)
if self.data is not None:
data = self.data.Pack(builder)
NestedUnionTestStart(builder)
if self.name is not None:
NestedUnionTestAddName(builder, name)
NestedUnionTestAddDataType(builder, self.dataType)
if self.data is not None:
NestedUnionTestAddData(builder, data)
NestedUnionTestAddId(builder, self.id)
nestedUnionTest = NestedUnionTestEnd(builder)
return nestedUnionTest