All the emitter framework changes I made to get the COI demo working

packages/emitter-framework/src/python/builtins.ts

@@ -35,6 +35,16 @@ export const decimalModule = createModule({
 export const typingModule = createModule({
   name: "typing",
   descriptor: {
-    ".": ["Any", "Literal", "Never", "NoReturn", "Protocol", "Tuple"],
+    ".": [
+      "Any",
+      "Literal",
+      "Never",
+      "NoReturn",
+      "Protocol",
+      "Tuple",
+      "Generic",
+      "TypeVar",
+      "Optional",
+    ],
   },
 });

packages/emitter-framework/src/python/components/class-declaration/class-declaration.test.tsx

@@ -1,4 +1,3 @@
-import { getOutput } from "#python/test-utils.jsx";
 import { Tester } from "#test/test-host.js";
 import { List } from "@alloy-js/core";
 import * as py from "@alloy-js/python";
@@ -7,6 +6,7 @@ import { describe, expect, it } from "vitest";
 import { ClassDeclaration } from "../../../../src/python/components/class-declaration/class-declaration.js";
 import { Method } from "../../../../src/python/components/class-declaration/class-method.js";
 import { EnumDeclaration } from "../../../../src/python/components/enum-declaration/enum-declaration.js";
+import { getOutput } from "../../test-utils.jsx";
 
 describe("Python Class from model", () => {
   it("creates a class", async () => {

packages/emitter-framework/src/python/components/class-declaration/class-declaration.tsx

@@ -1,7 +1,8 @@
-import { abcModule, dataclassesModule } from "#python/builtins.js";
+import { abcModule, dataclassesModule, typingModule } from "#python/builtins.js";
 import { type Children, For, List, mapJoin, Show } from "@alloy-js/core";
 import * as py from "@alloy-js/python";
 import { type Interface, type Model, type ModelProperty, type Operation } from "@typespec/compiler";
+import type { TemplateDeclarationNode } from "@typespec/compiler/ast";
 import type { Typekit } from "@typespec/compiler/typekit";
 import { createRekeyableMap } from "@typespec/compiler/utils";
 import { useTsp } from "../../../core/context/tsp-context.js";
@@ -152,16 +153,25 @@ function getExtendsType($: Typekit, type: Model | Interface): Children | undefin
  * @param abstract - Whether the class is abstract.
  * @returns The bases type for the class declaration.
  */
-function createBasesType($: Typekit, props: ClassDeclarationProps, abstract: boolean) {
-  const globalBasesType = isTypedClassDeclarationProps(props)
-    ? getExtendsType($, props.type)
-    : undefined;
-  let basesType = props.bases ? props.bases : (globalBasesType ?? undefined);
+function createBasesType(
+  $: Typekit,
+  props: ClassDeclarationProps,
+  abstract: boolean,
+  extraBases: Children[] = [],
+) {
+  if (isTypedClassDeclarationProps(props)) {
+    const extend = getExtendsType($, props.type);
+    if (extend) {
+      extraBases.push(extend);
+    }
+  }
+  const allBases = (props.bases ? props.bases : []).concat(extraBases);
+  const basesType = allBases.length > 0 ? allBases : undefined;
   if (!abstract) return basesType;
 
   const abcBase = abcModule["."]["ABC"];
-  if (Array.isArray(basesType)) return [abcBase, ...basesType];
-  if (basesType != null) return [abcBase, basesType];
+  if (Array.isArray(basesType)) return [...basesType, abcBase];
+  if (basesType != null) return [basesType, abcBase];
   return [abcBase];
 }
 
@@ -174,10 +184,48 @@ export function ClassDeclaration(props: ClassDeclarationProps) {
   const { $ } = useTsp();
 
   // If we are explicitly overriding the class as abstract or the type is not a model, we need to create an abstract class
-  let abstract =
+  const abstract =
     ("abstract" in props && props.abstract) || ("type" in props && !$.model.is(props.type));
-  let docElement = createDocElement($, props);
-  let basesType = createBasesType($, props, abstract);
+  const docElement = createDocElement($, props);
+
+  const extraBases = [];
+  let typeVars = null;
+  const typeArgs = [];
+  if (isTypedClassDeclarationProps(props)) {
+    if (
+      !props.type.isFinished &&
+      (props.type.node as TemplateDeclarationNode)?.templateParameters
+    ) {
+      const templateParameters = (props.type.node as TemplateDeclarationNode)?.templateParameters;
+      typeVars = (
+        <>
+          <For each={templateParameters} hardline>
+            {(node) => {
+              const typeVar = (
+                <py.FunctionCallExpression
+                  target={typingModule["."].TypeVar}
+                  args={[<py.Atom jsValue={node.id.sv} />]}
+                />
+              );
+              return <py.VariableDeclaration name={node.id.sv} initializer={typeVar} />;
+
+              // ("${node.id.sv}")`;
+              // return <py.Declaration name={String(node.id.sv)}></py.Declaration>;
+            }}
+          </For>
+        </>
+      );
+      for (const templateParamter of templateParameters) {
+        typeArgs.push(templateParamter.id.sv);
+      }
+    }
+
+    if (typeArgs.length > 0) {
+      extraBases.push(<py.TypeReference refkey={typingModule["."].Generic} typeArgs={typeArgs} />);
+    }
+  }
+
+  const basesType = createBasesType($, props, abstract, extraBases);
 
   if (!isTypedClassDeclarationProps(props)) {
     return (
@@ -199,12 +247,10 @@ export function ClassDeclaration(props: ClassDeclarationProps) {
 
   const refkeys = declarationRefkeys(props.refkey, props.type);
   let dataclass: any = null;
-  if (!abstract) {
-    // Array-based models should be rendered as normal classes, not dataclasses (e.g., model Foo is Array<T>)
-    const isArrayModel = $.model.is(props.type) && $.array.is(props.type);
-    if (!isArrayModel) {
-      dataclass = dataclassesModule["."]["dataclass"];
-    }
+  // Array-based models should be rendered as normal classes, not dataclasses (e.g., model Foo is Array<T>)
+  const isArrayModel = $.model.is(props.type) && $.array.is(props.type);
+  if (!isArrayModel) {
+    dataclass = dataclassesModule["."]["dataclass"];
   }
   const classBody = createClassBody($, props, abstract);
 
@@ -218,11 +264,13 @@ export function ClassDeclaration(props: ClassDeclarationProps) {
 
   return (
     <>
-      <Show when={dataclass}>
-        @{dataclass}
+      <Show when={!!typeVars}>
+        {typeVars}
         <hbr />
+        <line />
       </Show>
-      <Show when={abstract}>
+      <Show when={dataclass}>
+        @{dataclass}(kw_only=True)
         <hbr />
       </Show>
       <MethodProvider value={props.methodType}>

packages/emitter-framework/src/python/components/class-declaration/class-member.tsx

@@ -1,7 +1,7 @@
 import { typingModule } from "#python/builtins.js";
 import { type Children } from "@alloy-js/core";
 import * as py from "@alloy-js/python";
-import { isNeverType, type ModelProperty, type Operation } from "@typespec/compiler";
+import { type ModelProperty, type Operation } from "@typespec/compiler";
 import { useTsp } from "../../../core/context/tsp-context.js";
 import { efRefkey } from "../../utils/refkey.js";
 import { Atom } from "../atom/atom.jsx";
@@ -125,16 +125,21 @@ export function ClassMember(props: ClassMemberProps) {
 
   if ($.modelProperty.is(props.type)) {
     // Map never-typed properties to typing.Never
-    const isNever = isNeverType(props.type.type);
 
-    const unpackedType = isNever ? (typingModule["."]["Never"] as any) : (props.type.type as any);
+    const unpackedType = props.type.type;
     const isOptional = props.optional ?? props.type.optional ?? false;
-    const defaultValue: any = (props.type as any).defaultValue;
+    const defaultValue = props.type.defaultValue;
     const literalTypeNode = buildTypeNodeForProperty(unpackedType);
     const initializer = buildPrimitiveInitializerFromDefault(defaultValue, unpackedType, $);
-    const typeNode: Children = isNever
-      ? (typingModule["."]["Never"] as any)
-      : (literalTypeNode ?? <TypeExpression type={unpackedType} />);
+    const unpackedTypeNode: Children = literalTypeNode ?? <TypeExpression type={unpackedType} />;
+    const typeNode = isOptional ? (
+      <py.TypeReference
+        refkey={typingModule["."].Optional}
+        typeArgs={[unpackedTypeNode]}
+      ></py.TypeReference>
+    ) : (
+      unpackedTypeNode
+    );
 
     const interfaceMemberProps = {
       doc,

packages/emitter-framework/src/python/components/class-declaration/class-method.test.tsx

@@ -1,10 +1,10 @@
-import { getOutput } from "#python/test-utils.jsx";
 import { Tester } from "#test/test-host.js";
 import { getProgram } from "#test/utils.js";
 import { t } from "@typespec/compiler/testing";
 import { describe, expect, it } from "vitest";
 import { ClassDeclaration } from "../../../../src/python/components/class-declaration/class-declaration.js";
 import { Method } from "../../../../src/python/components/class-declaration/class-method.js";
+import { getOutput } from "../../test-utils.jsx";
 
 describe("interface methods with a `type` prop", () => {
   it("creates a class method from an interface method", async () => {

packages/emitter-framework/src/python/components/index.ts

@@ -1,3 +1,4 @@
 export * from "./atom/atom.jsx";
 export * from "./class-declaration/class-declaration.jsx";
+export * from "./enum-declaration/enum-declaration.jsx";
 export * from "./function-declaration/function-declaration.jsx";

packages/emitter-framework/src/python/components/type-expression/type-expression.tsx

@@ -1,9 +1,17 @@
 import { Experimental_OverridableComponent } from "#core/components/index.js";
 import { useTsp } from "#core/context/index.js";
 import { reportPythonDiagnostic } from "#python/lib.js";
-import { For } from "@alloy-js/core";
+import { code, For } from "@alloy-js/core";
 import * as py from "@alloy-js/python";
-import type { IntrinsicType, Model, Scalar, Type } from "@typespec/compiler";
+import {
+  isNeverType,
+  type IntrinsicType,
+  type Model,
+  type Scalar,
+  type TemplatedTypeBase,
+  type Type,
+} from "@typespec/compiler";
+import type { TemplateParameterDeclarationNode } from "@typespec/compiler/ast";
 import type { Typekit } from "@typespec/compiler/typekit";
 import { datetimeModule, decimalModule, typingModule } from "../../builtins.js";
 import { efRefkey } from "../../utils/refkey.js";
@@ -36,6 +44,9 @@ export function TypeExpression(props: TypeExpressionProps) {
   switch (type.kind) {
     case "Scalar": // Custom types based on primitives (Intrinsics)
     case "Intrinsic": // Language primitives like `string`, `number`, etc.
+      if (isNeverType(type)) {
+        return typingModule["."]["Never"];
+      }
       return <>{getScalarIntrinsicExpression($, type)}</>;
     case "Boolean":
     case "Number":
@@ -64,8 +75,13 @@ export function TypeExpression(props: TypeExpressionProps) {
         return <RecordExpression elementType={elementType} />;
       }
 
+      if (isTemplateVar(type)) {
+        return <TypeExpression type={type.templateMapper?.args[0] as Type} />;
+      }
       reportPythonDiagnostic($.program, { code: "python-unsupported-type", target: type });
       break;
+    case "TemplateParameter":
+      return code`${String((type.node as TemplateParameterDeclarationNode).id.sv)}`;
 
     // TODO: Models will be implemented separately
     // return <InterfaceExpression type={type} />;
@@ -157,7 +173,12 @@ function getScalarIntrinsicExpression($: Typekit, type: Scalar | IntrinsicType):
   return pythonType;
 }
 
+function isTemplateVar(type: Type): boolean {
+  return (type as TemplatedTypeBase).templateMapper !== undefined;
+}
+
 function isDeclaration($: Typekit, type: Type): boolean {
+  if (isTemplateVar(type)) return false;
   switch (type.kind) {
     case "Namespace":
     case "Interface":

packages/emitter-framework/src/python/index.ts

@@ -1 +1,2 @@
+export * from "./builtins.js";
 export * from "./components/index.js";

packages/emitter-framework/src/python/test-utils.tsx

@@ -12,11 +12,6 @@ import {
 
 export function getOutput(program: Program, children: Children[]): Children {
   const policy = py.createPythonNamePolicy();
-  const printOptions = {
-    printWidth: 80,
-    tabWidth: 4,
-    insertFinalNewLine: false,
-  };
   return (
     <Output
       program={program}
@@ -29,7 +24,6 @@ export function getOutput(program: Program, children: Children[]): Children {
         py.abcModule,
         py.enumModule,
       ]}
-      printOptions={printOptions}
       namePolicy={policy}
     >
       <py.SourceFile path="test.py">{children}</py.SourceFile>

packages/python/.gitignore

@@ -0,0 +1,9 @@
+# MacOS
+.DS_Store
+
+# Default TypeSpec output
+tsp-output/
+dist/
+
+# Dependency directories
+node_modules/

packages/python/eslint.config.js

@@ -0,0 +1,11 @@
+// @ts-check
+import eslint from "@eslint/js";
+import tsEslint from "typescript-eslint";
+
+export default tsEslint.config(
+  {
+    ignores: ["**/dist/**/*", "**/.temp/**/*"],
+  },
+  eslint.configs.recommended,
+  ...tsEslint.configs.recommended,
+);

packages/python/package.json

@@ -0,0 +1,44 @@
+{
+  "name": "python",
+  "version": "0.1.0",
+  "type": "module",
+  "main": "dist/src/index.js",
+  "exports": {
+    ".": {
+      "types": "./dist/src/index.d.ts",
+      "default": "./dist/src/index.js"
+    },
+    "./testing": {
+      "types": "./dist/src/testing/index.d.ts",
+      "default": "./dist/src/testing/index.js"
+    }
+  },
+  "peerDependencies": {
+    "@typespec/compiler": "workspace:^"
+  },
+  "dependencies": {
+    "@alloy-js/core": "^0.20.0",
+    "@alloy-js/python": "link:/Users/srice/code/alloy/packages/python",
+    "@typespec/emitter-framework": "workspace:^",
+    "prettier": "~3.6.2"
+  },
+  "devDependencies": {
+    "@alloy-js/cli": "^0.20.0",
+    "@types/node": "latest",
+    "@typescript-eslint/eslint-plugin": "^8.15.0",
+    "@typescript-eslint/parser": "^8.15.0",
+    "@typespec/compiler": "workspace:^",
+    "eslint": "^9.15.0",
+    "prettier": "^3.3.3",
+    "typescript": "^5.3.3"
+  },
+  "scripts": {
+    "build": "alloy build",
+    "test": "node --test 'dist/test**/*.test.js'",
+    "lint": "eslint src/ test/ --report-unused-disable-directives --max-warnings=0",
+    "lint:fix": "eslint . --report-unused-disable-directives --fix",
+    "format": "prettier .  --write",
+    "format:check": "prettier --check ."
+  },
+  "private": true
+}

packages/python/prettierrc.yaml

@@ -0,0 +1,8 @@
+trailingComma: "all"
+printWidth: 120
+quoteProps: "consistent"
+endOfLine: lf
+arrowParens: always
+plugins:
+  - "./node_modules/@typespec/prettier-plugin-typespec/dist/index.js"
+overrides: [{ "files": "*.tsp", "options": { "parser": "typespec" } }]