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CG-10697: TS-Promise-Chain (#417)
- Adds TSPromise class to help deal with promises more easily - adds ability to retreive TSPromiseChain from a functionCall node - convert to async/await blog - convert to async/await tutorial - convert to async/await example folder
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‎codegen-examples/examples/promises_to_async_await/README.md

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# Transform promise.then statements to async/await
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This example demonstrates how to use Codegen to automatically transform `promise.then` statements to `async/await`.
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> Here is an [open pull request](https://github.com/twilio/twilio-node/pull/1072) created in the [_official_ twilio node.js](https://www.twilio.com/docs/messaging/quickstart/node) repository using the promise to async/await transformation using Codegen.
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## How the Migration Script Works
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The script automates the entire migration process in a few key steps:
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1. **Promise Detection**
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```python
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# Get all promise chains in the codebase
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promise_chains = []
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for file in codebase.files:
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promise_chains = promise_chains + file.promise_chains
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```
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```python
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# Or get all promise chains in the current function
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function = codebase.get_function("function_name")
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promise_chains = function.promise_chains
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```
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```python
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# Or get the promise chain for the current function call
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function_call = codebase.get_function("function_name").function_calls[0]
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promise_chain = function_call.promise_chain
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```
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- Automatically identifies all promise chains in each file, function, or function call in the codebase
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- Uses Codegen's intelligent code analysis engine
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1. **Transformation**
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```python
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# Transform a promise chain to async/await (inplace)
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promise_chain.convert_to_async_await()
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codebase.commit()
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```
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```python
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# Or return the transformed code + clean up additonal business logic from .then blocks
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promise_statement = promise_chain.parent_statement
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new_code = promise_chain.convert_to_async_await(inplace_edit=False)
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promise_statement.edit(
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f"""
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{new_code}
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# handle additional business logic here
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"""
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)
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```
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- Replaces the promise chain with the async/await version
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- Handles function calls and function bodies automatically
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- Handles top-level varable assignments and return statements
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- Deals with ambiguous return blocks by adding annonymous functions where necessary
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- Carries over try/catch/finally blocks
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- Acknowledges implicit returns
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# Examples
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## Running the Migration on the [Official Twilio Node.js](https://github.com/twilio/twilio-node) Client Libary
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_1. Follow step by step in the [convert_promises_twilio_repository.ipynb](./convert_promises_twilio_repository.ipynb) notebook_
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_Or run codemod script directly:_
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```bash
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# Install Codegen
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pip install codegen
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# Run the promise to async/await migration
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python run.py
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```
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The script will:
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1. Initialize the codebase
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1. Find _all 592_ instances of `promise.then` statements with the base call called `operationPromise`
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1. Convert those to async/await style calls
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_IMPORTANT: ensure to run `npx prettier --write .` after the migration to fix indentation + linting_
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## Explore All The Covered Cases for the Conversion
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_Checkout the [promise_to_async_await.ipynb](./promise_to_async_await.ipynb) notebook_
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Currently, the `promise_chain.convert_to_async_await()` method handles the following cases:
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- `promise.then()` statements of any length
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- `promise.then().catch()` statements of any length
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- `promise.then().catch().finally()` statements of any length
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- Implicit returns -> `return promise.then()`
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- Top level variable assignments -> `let assigned_var = promise.then()`
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- Top level variable assignments -> `let assigned_var = promise.then()`
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- Ambiguous/conditional return blocks
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**IMPORTANT:**
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_There will be cases that the current `promise_chain.convert_to_async_await()` cannot handle. In those cases, either right your own transformation logic using the codegen-sdk or open an issue on the [Codegen](https://github.com/codegen-sh/codegen-sdk) repository._
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## Contributing
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Feel free to submit issues and any enhancement requests!

‎codegen-examples/examples/promises_to_async_await/convert_promises_twilio_repository.ipynb

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{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Convert Promises to Async/Await in the Twilio Node.js Client Library using Codegen\n",
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"\n",
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"This notebook will show you how to convert a repeated use of a promise chain to async await \n",
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"in the official twilio js client library twilio/twilio-node repository.\n",
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"\n",
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"1. Finds all methods containing operationPromise.then chains\n",
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"2. Converts the promise chain to use async await\n",
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"3. Gets rid of the callback handler by adding try catch directly in the function body"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"from codegen import Codebase\n",
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"from codegen.sdk.enums import ProgrammingLanguage\n",
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"from codegen.sdk.core.statements.statement import StatementType"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"print(\"Initializing codebase...\")\n",
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"codebase = Codebase(\"twilio/twilio-node\", programming_language=ProgrammingLanguage.TYPESCRIPT)\n",
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"print(\"Twilio repository initialized!\")"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"### 1. Find all Promise Chains in class methods with the base call being `operationPromise.then`"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# loop through all files -> classes -> methods to find promise the operationPromise chains\n",
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"operation_promise_chains = []\n",
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"unique_files = set()\n",
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"\n",
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"i = 0\n",
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"\n",
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"for _class in codebase.classes:\n",
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" for method in _class.methods:\n",
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" if method.name in [\"each\", \"setPromiseCallback\"]:\n",
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" print(\"skipping method\", method.name, \"...\")\n",
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" continue\n",
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"\n",
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" # Only process methods containing operationPromise\n",
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" if not method.find(\"operationPromise\"):\n",
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" continue\n",
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"\n",
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" # Find the first promise chain with then blocks\n",
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" for promise_chain in method.promise_chains:\n",
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" promise_statement = promise_chain.parent_statement\n",
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" operation_promise_chains.append({\"function_name\": method.name, \"promise_chain\": promise_chain, \"promise_statement\": promise_statement})\n",
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" unique_files.add(method.file.filepath)\n",
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" i += 1\n",
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" if i < 10:\n",
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" print(f\"Found operation promise in the {method.name} method in {method.file.filepath} file.\")"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"print(\"Number of Operation Promise Chains found:\", len(operation_promise_chains))\n",
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"print(\"Number of files affected:\", len(unique_files))"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"### 2. Convert *all* 592 Promise Chains to Async/Await \n",
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"\n",
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"*Additionally...* Add a Try/Catch to Eliminate the Callback Handler"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"i = 0\n",
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"assignment_variable_name = \"operation\"\n",
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"\n",
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"for promise_chain_dict in operation_promise_chains:\n",
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" promise_chain = promise_chain_dict[\"promise_chain\"]\n",
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" promise_statement = promise_chain_dict[\"promise_statement\"]\n",
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" function_name = promise_chain_dict[\"function_name\"]\n",
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" # ---------- CONVERT PROMISE CHAIN TO ASYNC AWAIT ----------\n",
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" async_await_code = promise_chain.convert_to_async_await(assignment_variable_name=assignment_variable_name, inplace_edit=False)\n",
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"\n",
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" if i < 10:\n",
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" print(f\"converting {function_name} promise chain to async/await.\")\n",
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"\n",
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" i += 1\n",
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" # ---------- ADD TRY CATCH BLOCK INSTEAD OF CALLBACK HANDLER ----------\n",
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" new_code = f\"\"\"\\\n",
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" try {{\n",
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" {async_await_code}\n",
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"\n",
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" if (callback) {{\n",
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" callback(null, {assignment_variable_name});\n",
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" }}\n",
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"\n",
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" return {assignment_variable_name};\n",
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" }} catch(err: any) {{\n",
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" if (callback) {{\n",
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" callback(err);\n",
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" }}\n",
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" throw err;\n",
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" }}\"\"\"\n",
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"\n",
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" promise_statement.edit(new_code)\n",
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"\n",
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" # ---------- CLEAN UP CALLBACK HANDLER ASSIGNMENT AND SUBSEQUENT RETURN STATEMENT ----------\n",
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" statements = promise_statement.parent.get_statements()\n",
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" return_stmt = next((stmt for stmt in statements if stmt.statement_type == StatementType.RETURN_STATEMENT), None)\n",
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" assign_stmt = next((stmt for stmt in reversed(statements) if stmt.statement_type == StatementType.ASSIGNMENT), None)\n",
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"\n",
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" if return_stmt:\n",
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" return_stmt.remove()\n",
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" if assign_stmt:\n",
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" assign_stmt.remove()\n",
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"\n",
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"codebase.commit()"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"After making the changes, ensure to run *`npx prettier --write .`* to format line indentation and linting errors."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# reset the formatting\n",
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"codebase.reset()"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"codebase = Codebase(\"/Users/tawsifkamal/Documents/codegen-repos/twilio-node\", programming_language=ProgrammingLanguage.TYPESCRIPT)"
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": ".venv",
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"language": "python",
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"name": "python3"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 3
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.13.0"
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}
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},
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"nbformat": 4,
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"nbformat_minor": 2
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}

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