値オブジェクト / Value Object

フロントエンド百物語で発表した資料です。

Transcript

1. ஋ΦϒδΣΫ τ "VH
   
   
   
   ϑϩϯ τΤϯ υඦ෺ޠ
2. ஋ΦϒδΣΫ τͱ͸ w %%% ʢυϝΠϯۦಈઃܭʣ Ͱड़΂ΒΕΔ֓೦
   w +BWB4DSJQUʹ͸TUSJOH
   OVNCFS
   CPPMFBOͱ͍͏ ϓϦ ϛςΟ ϒܕ͕͋Δ
   w TUSJOH
   OVNCFSΛ5ZQF4DSJQUͰͦͷ··ѻΘͣ
 ஋ΦϒδΣΫ τͱͯ͠ఆٛ͢Δ͜ͱͰɺ ༷ʑͳ஋ΛࣝผՄೳʹ͢Δ
3. ࣮ࡍͷҊ݅Ͱͷྫ w "2018/8"ͱ͍͏stringΛѻΘͣʹYearMonthܕͱ͢Δ
   w "-0900"ͱ͍͏stringΛѻΘͣʹTimeZoneܕͱ͢Δ
   w 1, 2, 3ͱ͍͏numberͰ͸ͳ͘UserIdܕͱ͢Δ
   w Observable<[number, string, number, number]>ͩͱҙຯෆ໌͕ͩ
 Observable<[UserId, TimeZone, PageNumber, DisplayCount]>
 ͱఆٛͰ͖Δ
4. ࣮૷ྫ export abstract class Value<T> { constructor(protected value: T) { // } toString(): string { return this.value.toString(); } valueOf(): T { return this.value; } eq(other: Value<T>): boolean { return this.value === other.value; } }
5. export class TimeZone extends StringValue { TimeZone: ProhibitDuckTyping; static UTC(): TimeZone { return new TimeZone('+0000'); } /** * JST ͷ৔߹ɺ -540 Λ +0900 ʹม׵͢Δɻ */ static offsetToIsoTimeZone(offset: number): TimeZone { const min = Math.abs(offset); const isoTimeZone = [ `00${Math.floor(min / 60)}`.slice(-2), `00${min - Math.floor(min / 60) * 60}`.slice(-2), ].join(''); const sign = offset <= 0 ? '+' : '-'; return new TimeZone(`${sign}${isoTimeZone}`); } constructor(protected value: string) { super(value); assert(/^[+-]\d{4}/.test(value), `"${value}" ͸ɺλΠϜκʔϯͷϑΥʔϚοτͰ͸͋Γ·ͤΜ`); } }
6. 1SPIJCJU%VDL5ZQJOH w Ҋ݅಺Ͱੜ·ΕͨϫʔΫΞϥ΢ϯ υ ʢ5ZQF4DSJQUͷਖ਼ࣜͳٕज़ͷ໊শͰ͸ͳ͍ʣ
   w 5ZQF4DSJQU͸
 class A { value: string }
   ͱ
 class B { value: string }
   Λ
 ࠞಉͯ͠ѻ͏ ͜ͱ͕Ͱ͖Δ
   w ߏ੒͢ΔϓϩύςΟͷ໊শͱܕͱ૊Έ߹Θ͕ͤಉ͡ͳΒ͹ಉ͡ΠϯλϑΣʔεͰ
 ͋ΔͱΈͳ͞ΕΔ
7. 1SPIJCJU%VDL5ZQJOH w class A { value: string; A: ProhibitDuckTyping; }
   
 class B { value: string; B: ProhibitDuckTyping; }
   
 ͷΑ ͏ʹ͢Ε͹ϓϩύςΟ໊͕"
   #ͰҟͳΔͷͰผͷܕѻ͍Ͱ͖Δ
   w 1SPIJCJU%VDL5ZQJOH͸࣮࣭͸
 export type ProhibitDuckTyping = void;