番茄钟的设计与实现。design of tomato-clock

domain entities

countdown-period

• duration
• default duration
• name

counter

• isRunning
• shouldLoop

counter has one or more countdown-periods

usecase

resume and pause

1. this event is captured
2. no business rules
3. isRunning = !isRunning
4. no output

set duration of a countdown-period

1. this event is captured
2. business rules
   • 1 <= duration <= 60
3. depends on isRunning
   1. if isRunning == true, do nothing
   2. set the specified countdown-period’s duration.
4. no output

countdown

1. execute every 1 second
2. depends on isRunning
   1. if isRunning == true, increase internal counter by one
   2. otherwise, do nothing
3. no output

reset

1. this event is captured
2. no business rules
3. restore initial state
   1. isRunning = false
   2. for every countdown-period, duration = default duration

components/classes

countdown-period repository

It is a sequence of countdown-period.

This class provides a factory methodfromArray(periods: CountDownPeriod[]).

It provides whichDuration(time: number): CountDownPeriod which throws NoDurations if sequence is empty. If time is bigger than the sum of durations of all periods, it overflows. It throws InvalidTimeValue if time is negative.

countdown-period

This is a simple value entity representing basic information of periods. Instances are mutated by setDuration(duration: number) and reset. Constructor are fairly simple: ctor(name: string, defaultDuration: number). duration is exposed as public attribute.

clock

public state

• readonly time: integer the number of seconds elapsed with isRunning being true since this instance is created.

methods

• reset(): call stop(), then set time to 0.
• start(): set isRunning to true, id = setTimeout(()=>{...}, 1000).
• stop(): set isRunning to false, clearTimeout(id).

controller

this entity handles aforementioned events.