pretalk

Author: ramalho

README.md

@@ -1,3 +1,55 @@
 # protocol_examples
 
 Examples using `typing.Protocol` from PEP 544
+
+## Notes
+
+### Classic Example: a "file-like object"
+
+From [_PEP 333 – Python Web Server Gateway Interface v1.0_](https://peps.python.org/pep-0333/) (2003):
+
+
+>    To be considered “file-like”, the object supplied by the application
+must have a `read()` method that takes an optional size argument.
+
+The words "file-like" (or "file like") appear with similar implied meaning
+in the Python 3.12 distribution:
+
+- 148 times in the documentation;
+- 92 times in code comments (`.py` or `.c` source files).
+
+Also, 30 times across 21 PEPs (100, 214, 258, 282, 305, 310, 333, 368, 400, 441, 444, 578, 680, 691, 3116, 3119, 3143, 3145, 3154, 3156, 3333).
+
+
+Definition in `Lib/wsgiref/types.py`:
+
+```python
+class _Readable(Protocol):
+    def read(self, size: int = ..., /) -> bytes: ...
+```
+
+### Examples as of 2024-05-23
+
+`typing.Protocol` definitions found with `ripgrep`:
+
+```shell
+rg "Protocol\)" -g '*.pyi' | sort
+```
+
+- 120 definitions on `typeshed/stdlib` (Python standard library)
+- 134 definitions on `typeshed/stubs` (external packages)
+
+
+
+### Cases to study
+
+- `importlib/resources/abc.py`: `class Traversable(Protocol)`
+with several abstract and concrete methods, looks like an ABC but derives from `typing.Protocol`
+
+
+### Not `typing.Protocol`
+
+- `asyncio/protocols.py`: defines classes `BaseProtocol`, `Protocol` etc. for network protocols
+
+
+

ast_hacks/test_experiments.py

@@ -0,0 +1,15 @@
+from ast import parse, Module, FunctionDef
+import inspect
+
+
+def double_any[T](x: T) -> T:
+    return x * 2
+
+
+def test_double_any():
+    tree = parse(inspect.getsource(double_any))
+    match tree:
+        case Module(body=[FunctionDef(type_params=tps)]):
+            tv=tps[0]
+
+    assert tv.name == 'T'