10 More Days to Become a Better Developer by Daniel Scheufler

Author:Daniel Scheufler [Daniel Scheufler]
Language: eng
Format: epub, pdf
Publisher: leanpub.com
Published: 2022-11-19T00:00:00+00:00

You can read more about the Factory Design Pattern here or return to Day 2

Software Pattern - Adapter

The Adapter pattern is a structural pattern. It deals with the structure of objects in code. The Adapter acts as passthru layer adapting two different interfaces. Think of it like a AC-USB adapter for charging your devices. The Adapter’s job is to allow different interfaces to interoperate. Being a structural pattern, you should favor keeping the implementation of the adapter pure with minimum additional logic to enable the adaptation. You can see a simplistic example below, where we will convert a third party library’s interface to one our system can use:

1 // Our Target Interface 2 interface IAcmeCoMediaPlayer { 3 function play(): Stream; // starts playback of Media,\ 4 into result Stream 5 function seek(timeInSec: Number): boolean; // moves c\ 6 ursor to indicated point in time of Media, returns true i\ 7 f successful 8 function stop(): void; // stops playback of Media int\ 9 o existing Streams if any. 10 } 11 12 // Support Classes for Third Party Media Reader 13 type MediaResult = { 14 wasSuccessful: boolean; 15 errorMsg?: string; 16 } 17 18 type ThirdPartyStream = {} 19 20 class ThirdPartyMediaPlayer { 21 construtor(inputPath: string){ 22 // do something wtih inputPath 23 } 24 25 function start(): ThirdPartyStream { 26 // starts playing inputPath content into ThirdPar\ 27 tyStream object 28 } 29 30 function goTo(min: Number, sec: Numnber): MediaResult{ 31 // seeks position in inputPath 32 } 33 34 function stop(): MediaResult { 35 // stops the playback if possible, returns error \ 36 is not already playing. 37 } 38 } 39 40 class MediaPlayerAdapter implements IAcmeCoMediaPlayer { 41 42 _wrappedPlayer: ThirdPartyMediaPlayer; 43 44 constructor(inputPath: string)}{ 45 _wrappedPlayer - new ThirdParthMediaPlayer(inputP\ 46 ath); 47 } 48 49 function convertedCommonStreamOf(thirdPartyStream: Th\ 50 irdPartyStream): Stream {} 51 function play(): Stream{ 52 return convertedCommonStreamOf(_wrappedPlayer.sta\ 53 rt()); 54 } 55 56 57 function seek(timeInSec: Number): boolean { 58 // need to convert arguments 59 const inputMin = floor(timeInSec / 60); 60 const remainingSec = timeInSec % 60; 61 62 const thirdPartySeekResult = _wrappedPlayer.goTo(\ 63 inputMin, remainingSec); 64 // might console log the error message here if ne\ 65 cessary 66 return thirdPartySeekResult.wasSuccessful; 67 } 68 69 function stop(): void { 70 _wrappedPlayer.stop(); 71 } 72 }

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