Merge pull request #75 from streamich/debug

`@debug` decorator

README.md

@@ -23,6 +23,11 @@ Useful TypeScript utilities.
 
 ---
 
+- `@debug` — a class method or function decorator, which logs
+  the input and output of the function in non-production environments.
+
+---
+
 - `hash` — a fast and simple utility, which hashes a string to an integer. Useful
   for generating a shard index of a record based on its ID.
 

src/__bench__/lru.bench.ts

@@ -27,7 +27,7 @@ const caches: Cache[] = [
     create: (limit: number) => lru(limit),
   },
 ];
-const limits = [10, 100, 1000, 10000];
+const limits = [10, 100, 1000, 10000, 100000];
 // const iterations = [10, 100, 1000, 10000];
 const iterations = [1000000];
 // const reads = [true, false];

src/debug.ts

@@ -0,0 +1,36 @@
+/* tslint:disable no-invalid-this no-console */
+
+let id = 0;
+
+export function debug<This, Args extends any[], Return>(name?: string) {
+  return (
+    fn: (this: This, ...args: Args) => Return,
+    context?: ClassMethodDecoratorContext<This, (this: This, ...args: Args) => Return>,
+  ) => {
+    if (process.env.NODE_ENV !== 'production') {
+      return function (this: This, ...args: Args): Return {
+        id++;
+        const idStr = id.toString(36);
+        const currentName =
+          name ?? (this ? this.constructor?.name + '.' : '') + (String(context?.name) ?? fn.name ?? 'anonymous');
+        console.log('%cRUN', 'background:white;color:blue', idStr, currentName, ...args);
+        try {
+          const res = fn.apply(this, args);
+          if (res instanceof Promise) {
+            res.then(
+              (res) => console.log('%cSUC', 'background:green;color:white', idStr, currentName, res),
+              (err) => console.log('%cERR', 'background:red;color:white', idStr, currentName, err),
+            );
+            return res;
+          }
+          console.log('%cSUC', 'background:green;color:white', idStr, currentName, res);
+          return res;
+        } catch (err) {
+          console.log('%cERR', 'background:red;color:white', idStr, currentName, err);
+          throw err;
+        }
+      };
+    }
+    return fn;
+  };
+}

src/index.ts

@@ -5,6 +5,7 @@ export * from './concurrency';
 export {once} from './once';
 export {concurrency as concurrencyDecorator} from './concurrencyDecorator';
 export * from './dataUri';
+export * from './debug';
 export * from './Defer';
 export * from './fanout';
 export * from './go';