improv: decorate methods without destructuring args (#4345)

Author: dreamorosi

packages/logger/src/Logger.ts

@@ -13,7 +13,7 @@ import {
   getXRayTraceIdFromEnv,
   isDevMode,
 } from '@aws-lambda-powertools/commons/utils/env';
-import type { Context, Handler } from 'aws-lambda';
+import type { Callback, Context, Handler } from 'aws-lambda';
 import merge from 'lodash.merge';
 import {
   LogJsonIndent,
@@ -493,19 +493,17 @@ class Logger extends Utility implements LoggerInterface {
       // access `myClass` as `this` in a decorated `myClass.myMethod()`.
       descriptor.value = async function (
         this: Handler,
-        event,
-        context,
-        callback
+        ...args: [unknown, Context, Callback]
       ) {
         loggerRef.refreshSampleRateCalculation();
-        loggerRef.addContext(context);
-        loggerRef.logEventIfEnabled(event, options?.logEvent);
+        loggerRef.addContext(args[1]);
+        loggerRef.logEventIfEnabled(args[0], options?.logEvent);
         if (options?.correlationIdPath) {
-          loggerRef.setCorrelationId(event, options?.correlationIdPath);
+          loggerRef.setCorrelationId(args[0], options?.correlationIdPath);
         }
 
         try {
-          return await originalMethod.apply(this, [event, context, callback]);
+          return await originalMethod.apply(this, args);
         } catch (error) {
           if (options?.flushBufferOnUncaughtError) {
             loggerRef.flushBuffer();

packages/metrics/src/Metrics.ts

@@ -598,17 +598,15 @@ class Metrics extends Utility implements MetricsInterface {
       // access `myClass` as `this` in a decorated `myClass.myMethod()`.
       descriptor.value = async function (
         this: Handler,
-        event: unknown,
-        context: Context,
-        callback: Callback
+        ...args: [unknown, Context, Callback]
       ): Promise<unknown> {
         if (captureColdStartMetric) {
-          metricsRef.captureColdStartMetric(context.functionName);
+          metricsRef.captureColdStartMetric(args[1].functionName);
         }
 
         let result: unknown;
         try {
-          result = await originalMethod.apply(this, [event, context, callback]);
+          result = await originalMethod.apply(this, args);
         } finally {
           metricsRef.publishStoredMetrics();
         }

packages/parser/src/parserDecorator.ts

@@ -1,6 +1,6 @@
 import type { HandlerMethodDecorator } from '@aws-lambda-powertools/commons/types';
 import type { StandardSchemaV1 } from '@standard-schema/spec';
-import type { Context, Handler } from 'aws-lambda';
+import type { Callback, Context, Handler } from 'aws-lambda';
 import { parse } from './parser.js';
 import type { Envelope, ParserOptions } from './types/index.js';
 import type { ParserOutput } from './types/parser.js';
@@ -75,21 +75,22 @@ export const parser = <
 >(
   options: ParserOptions<TSchema, TEnvelope, TSafeParse>
 ): HandlerMethodDecorator => {
-  return (_target, _propertyKey, descriptor) => {
-    // biome-ignore lint/style/noNonNullAssertion: The descriptor.value is the method this decorator decorates, it cannot be undefined.
-    const original = descriptor.value!;
+  return (
+    _target: unknown,
+    _propertyKey: string | symbol,
+    descriptor: PropertyDescriptor
+  ) => {
+    const original = descriptor.value;
 
     const { schema, envelope, safeParse } = options;
 
     descriptor.value = async function (
       this: Handler,
-      event: ParserOutput<TSchema, TEnvelope, TSafeParse>,
-      context: Context,
-      callback
+      ...args: [ParserOutput<TSchema, TEnvelope, TSafeParse>, Context, Callback]
     ) {
-      const parsedEvent = parse(event, envelope, schema, safeParse);
+      const parsedEvent = parse(args[0], envelope, schema, safeParse);
 
-      return original.call(this, parsedEvent, context, callback);
+      return original.apply(this, [parsedEvent, ...args.slice(1)]);
     };
 
     return descriptor;