From 9bef4bf40944b1743185afc4466b77bdd2de13a2 Mon Sep 17 00:00:00 2001
From: Mayur Kale <mayurkale@google.com>
Date: Tue, 22 Oct 2019 17:31:27 -0700
Subject: [PATCH] fix: avoid casting

---
 packages/opentelemetry-metrics/src/Handle.ts |  2 +-
 packages/opentelemetry-metrics/src/Meter.ts  | 12 ++++++++++--
 packages/opentelemetry-metrics/src/Metric.ts |  4 ++--
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/packages/opentelemetry-metrics/src/Handle.ts b/packages/opentelemetry-metrics/src/Handle.ts
index 88a39245d0f..5d55ebbe08b 100644
--- a/packages/opentelemetry-metrics/src/Handle.ts
+++ b/packages/opentelemetry-metrics/src/Handle.ts
@@ -98,7 +98,7 @@ export class GaugeHandle extends BaseHandle implements types.GaugeHandle {
 /**
  * MeasureHandle is an implementation of the {@link MeasureHandle} interface.
  */
-export class MeasureHandle implements types.MeasureHandle {
+export class MeasureHandle extends BaseHandle implements types.MeasureHandle {
   record(
     value: number,
     distContext?: types.DistributedContext,
diff --git a/packages/opentelemetry-metrics/src/Meter.ts b/packages/opentelemetry-metrics/src/Meter.ts
index abeb5649505..af48f68df8c 100644
--- a/packages/opentelemetry-metrics/src/Meter.ts
+++ b/packages/opentelemetry-metrics/src/Meter.ts
@@ -16,7 +16,12 @@
 
 import * as types from '@opentelemetry/types';
 import { ConsoleLogger } from '@opentelemetry/core';
-import { CounterHandle, GaugeHandle, MeasureHandle } from './Handle';
+import {
+  CounterHandle,
+  GaugeHandle,
+  MeasureHandle,
+  BaseHandle,
+} from './Handle';
 import { Metric, CounterMetric, GaugeMetric } from './Metric';
 import {
   MetricOptions,
@@ -115,7 +120,10 @@ export class Meter implements types.Meter {
    * @param name The name of the metric.
    * @param metric The metric to register.
    */
-  private _registerMetric<T>(name: string, metric: Metric<T>): void {
+  private _registerMetric<T extends BaseHandle>(
+    name: string,
+    metric: Metric<T>
+  ): void {
     if (this._metrics.has(name)) {
       throw new Error(
         `A metric with the name ${name} has already been registered.`
diff --git a/packages/opentelemetry-metrics/src/Metric.ts b/packages/opentelemetry-metrics/src/Metric.ts
index a20931631dc..d9ade423202 100644
--- a/packages/opentelemetry-metrics/src/Metric.ts
+++ b/packages/opentelemetry-metrics/src/Metric.ts
@@ -26,7 +26,7 @@ import {
 } from './export/types';
 
 /** This is a SDK implementation of {@link Metric} interface. */
-export abstract class Metric<T> implements types.Metric<T> {
+export abstract class Metric<T extends BaseHandle> implements types.Metric<T> {
   protected readonly _monotonic: boolean;
   protected readonly _disabled: boolean;
   protected readonly _logger: types.Logger;
@@ -100,7 +100,7 @@ export abstract class Metric<T> implements types.Metric<T> {
     return {
       descriptor: this._metricDescriptor,
       timeseries: Array.from(this._handles, ([_, handle]) =>
-        ((handle as unknown) as BaseHandle).getTimeSeries(timestamp)
+        handle.getTimeSeries(timestamp)
       ),
     };
   }