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")
```
Using the : syntax leads to non member attributes.
> If an attribute is defined in the class body with a type annotation
> but with no assigned value, a type checker should assume this is a non-member attribute
```
class Pet(Enum):
genus: str # Non-member attribute
species: str # Non-member attribute
CAT = 1 # Member attribute
DOG = 2 # Member attribute
```
https://typing.python.org/en/latest/spec/enums.html#defining-members
This prevents the include of the type defined in the pyi,
otherwise this leads to error message like this:
error: Name XYZ already defined (possibly by an import) [no-redef]
* [Python] Use correct type for str with None
Otherwise mypy will correctly flag code like this
def __init__(self):
self.fooBar = None # type: Optional[str]
error: Incompatible types in assignment (expression has type "None", variable has type "str")
* [Python] Make list type optional as they can contain None
This allows enums to be type check with mypy.
They will still behave like ints ->
> IntEnum is the same as Enum,
> but its members are also integers and can be used anywhere
> that an integer can be used.
> If any integer operation is performed with an IntEnum member,
> the resulting value loses its enumeration status.
https://docs.python.org/3/library/enum.html#enum.IntEnum
Only if the --python-typing flag is set.
* [Python] Generate `.pyi` stub files when `--python-typing` is on.
To support this change, the following modifications were made:
- added a new option to disable `numpy` helpers generation;
- added a new flag to control the target Python version:
`--python-version` can be one of the following:
- `0.x.x` – compatible with any Python version;
- `2.x.x` – compatible with Python 2;
- `3.x.x` – compatible with Python 3.
- added codegen utilities for Python;
- added a note that the generated .py file is empty.
* [Python] Update Bazel build rules.
* [Python] Update Bazel build rules.
* [Python] Run buildifier on BUILD.bazel files.
---------
Co-authored-by: Derek Bailey <derekbailey@google.com>
* optionally generate type prefixes and suffixes for python code
* fix codegen error when qualified name is empty
* WIP: Python typing
* more progress towards python typing
* Further iterate on Python generated code typing
* clang-format
* Regenerate code
* add documentation for Python type annotations option
* generate code with Python type annotations
* handle forward references
* clang-format
* feat: Fixed the issue with nested unions relying on InitFromBuf.
Problem: Issue #7569
Nested Unions were broken with the introduction of parsing buffers with an initial encoding offset.
Fix:
Revert the InitFromBuf method to the previous version and introduction of InitFromPackedBuf that allows
users to read types from packed buffers applying the offset automatically.
Test:
Added in TestNestedUnionTables to test the encoding and decoding ability using a nested table with a
union field.
* fix: Uncommented generate code command
