(core): Add Duration.minus method

[moltar]

There is already a Duration.plus method which allows to add two durations together.

However, there is no Duration.minus.

aws-cdk/packages/@aws-cdk/core/lib/duration.ts

Lines 106 to 110 in efe5112

	public plus(rhs: Duration): Duration {
	const targetUnit = finestUnit(this.unit, rhs.unit);
	const total = convert(this.amount, this.unit, targetUnit, {}) + convert(rhs.amount, rhs.unit, targetUnit, {});
	return new Duration(total, targetUnit);
	}

Use Case

Ability to subtract one duration from another.

For example, a CloudWatch trigger that executes a lambda every 5 minutes.

At the same time, I want to avoid race conditions, so I want to set the Lambda timeout to slightly less than 5 minutes.

Proposed Solution

const ruleSchedule = Duration.minutes(5)
const lambdaTimeout = ruleSchedule.minus(Duration.seconds(10))

Other

I tried creating a Duration with a negative value, to then do simple math, but that is not allowed.

aws-cdk/packages/@aws-cdk/core/lib/duration.ts

Line 96 in efe5112

throw new Error(`Duration amounts cannot be negative. Received: ${amount}`);

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change

---

This is a 🚀 Feature Request

[rix0rrr]

Sounds like fun!

[github-actions]

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