Tips for using PHP interfaces

absrtact: in the process of programming we should learn how to use the interface to change our lives, greatly enhance the ability of self. Interface is not a new feature, but very important, let's take a small example of the interface. ...

Fictitious a Documentstore class, this class is responsible for collecting text from different resources. You can read HTML from a remote URL, read a resource, or collect terminal command output.

Class documentstore{protected $data = [];        Public Function adddocument (documenttable $document) {$key = $document->getid ();        $value = $document->getcontent ();            $this->data[key] = $value;    } public Function getdocuments () {return $this->data; }    }

Since the parameters of the Adddocument () method can only be instances of documenttable classes, how can you define Documentstore classes? In fact, documenttable is not a class, it is an interface;

interface documenttable{Public Function getId ();    Public function getcontent (); }

This interface defines the table name, and any object that implements the Documenttable interface must provide a public getid () method and a public getcontent () method.

> But what's the use of doing this? The advantage of this is that we can define the classes that are stable, and we can use very different methods. The following is a way to get HTML from a remote URL using curl.

Class HTMLDocument implements documenttable{protected $url;    Public function __construct ($url) {$this->url = $url;    } public Function GetId () {return $this->url;        Public Function getcontent () {$ch = Curl_init ();        curl_setopt ($ch, Curlopt_url, $this->url);        curl_setopt ($ch, curlopt_returntransfer,1);        curl_setopt ($ch, curlopt_connecttimeout,3);        curl_setopt ($ch, curlopt_followlocation,1);        curl_setopt ($ch, curlopt_maxredirs,3);        Curl_close ($ch);    return $THML; }}

Class Streamdocument implements documenttable{protected $resource;    protected $buffer;        Public function __construct ($resource, $buffer = 4096) {$this->resource= $resource;    $this->buffer= $buffer; } public Function GetId () {return ' resource-'. (    int) $this->resource;        } public Function GetContent () {$streamContent = ';        Rewind ($this->resource);        while (feof ($this->resource) = = = False) {$streamContent. = fread ($this->resource, $this->buffer);    } return $streamContent; }}

Class Commandoutdocument implements documenttable{protected $command;    Public function __construct ($command) {$this->command= $command;    } public Function GetId () {return $this->command;    } public Function GetContent () {return shell_exec ($this->command); }}

$documentStore = new Documentstore ();//Add HTML Document $htmldoc = new HTMLDocument (' https://www.i360.me '); $documentStore- >adddocument ($HTMLDOC);//Add flow document $streamdoc = new Streamdocument (fopen (' stream.txt ', ' RB ')); $documentStore Adddocument ($streamDOC);//Add terminal command Document $cmddoc = new Commandoutdocument (' cat/etc/hosts '); $documentStore Adddocument ($command);p Rint_r ($documentStore->getdocuments ());d ie;

Here Htmldocument,streamdocument,commandoutdocument these three classes have nothing in common, just implement the same interface.