[draft] plugin_fn extractors

bin/src/py.rs

@@ -51,15 +51,15 @@ fn get_export<R: std::fmt::Debug>(
     let n_args = f.args.args.len();
     let has_return = f.returns.is_some();
 
-    if is_plugin_fn && n_args > 0 {
-        anyhow::bail!(
-            "plugin_fn expects a function with no arguments, {func} should have no arguments"
-        );
-    }
+    // if is_plugin_fn && n_args > 0 {
+    //     anyhow::bail!(
+    //         "plugin_fn expects a function with no arguments, {func} should have no arguments"
+    //     );
+    // }
     Ok(Export {
         name: func,
         is_plugin_fn,
-        params: vec![wagen::ValType::I64; n_args],
+        params: vec![wagen::ValType::I64; 0],
         results: if is_plugin_fn {
             vec![wagen::ValType::I32]
         } else if has_return {

examples/plugin-fn-param-extractors/plugin.py

@@ -0,0 +1,27 @@
+import extism
+from dataclasses import dataclass
+
+@dataclass
+class Count(extism.Json):
+    count: int
+
+@dataclass
+class CountVowelsInput(extism.Json):
+    text: str
+
+@extism.plugin_fn
+def count_vowels(cfg: extism.Config, input: str) -> Count:
+    msg = cfg.get_str("message")
+    extism.log(extism.LogLevel.Info, f"Config: {msg}")
+    extism.log(extism.LogLevel.Info, f"Input: {input}")
+
+
+@extism.plugin_fn
+def count_vowels_dataclass(input: CountVowelsInput) -> Count:
+    extism.log(extism.LogLevel.Info, f"Json Input: {input.text}")
+
+
+@extism.plugin_fn
+def count_vowels_http(http: extism.Http) -> Count:
+    resp = http.request("http://www.example.com")
+    extism.log(extism.LogLevel.Info, f"Response: {resp}")

examples/plugin-fn-param-extractors/readme.md

@@ -0,0 +1,28 @@
+
+## Building the example 
+
+```sh
+./build.py
+./extism-py examples/plugin-fn-param-extractors/plugin.py -o examples/plugin-fn-param-extractors/out.wasm
+
+```
+
+## Calling the example functions
+
+```sh
+extism call examples/plugin-fn-param-extractors/out.wasm count_vowels \
+   --wasi \
+   --input='Hello World Test!' \
+   --log-level=info \
+   --config message="hello"
+
+extism call examples/plugin-fn-param-extractors/out.wasm count_vowels_dataclass \
+   --wasi \
+   --input='{"text": "Hello"}' \
+   --log-level=info
+
+extism call examples/plugin-fn-param-extractors/out.wasm count_vowels_http \
+   --wasi \
+   --allow-host '*' \
+   --log-level=info
+```

lib/src/prelude.py

@@ -1,10 +1,12 @@
 from typing import Union, Optional
 import json
+import inspect
 from enum import Enum
 from abc import ABC, abstractmethod
 from datetime import datetime
 from base64 import b64encode, b64decode
 from dataclasses import is_dataclass
+from functools import partial
 
 import extism_ffi as ffi
 
@@ -213,12 +215,37 @@ def wrapper(*args):
 def plugin_fn(func):
     """Annotate a function that will be called by Extism"""
     global __exports
-    __exports.append(func)
-
-    def inner():
-        return func()
-
-    return inner
+    def _handle_arg(arg_name: str, arg_type: type):
+        match (arg_name, arg_type):
+            case (_, _type) if _type is Config:
+                return Config
+            case (_, _type) if _type is Http:
+                return Http
+            case _:
+                raise ValueError(f"Unsupported argument")
+
+
+
+    sig = inspect.signature(func)
+    annotated_args = {k: v.annotation for k, v in sig.parameters.items()}
+    if "input" in annotated_args:
+        input_arg = annotated_args.pop("input")
+    else:
+        input_arg = None
+    func_args = {k: _handle_arg(k, v) for k, v in annotated_args.items()}
+    func_args = {k: v for k, v in func_args.items() if v is not None}
+    annotated_func = partial(func, **func_args)
+
+    def _defered_input():
+        fn_input = input(input_arg)
+        return annotated_func(input=fn_input)
+
+    if input_arg:
+        __exports.append(_defered_input)
+        return _defered_input
+    else:
+        __exports.append(annotated_func)
+        return annotated_func
 
 
 def shared_fn(f):

rust-toolchain.toml

@@ -0,0 +1,3 @@
+[toolchain]
+channel = "1.81.0"
+targets = ["wasm32-wasi"]