静的メソッドのコンテキスト内で$thisを使ってメソッドを呼んでみる

下記のコードだとEntryのdoit()がエントリーポイントで、ModelのdoSomething()が呼ばれ、パッと見Modelのsave()が呼ばれるように見えるが……

<?php

namespace Sample;

class Entry {
    function doit() {
        Model::doSomething();
    }

    public function save() {
        echo __METHOD__;
    }
}

class Model {
    public function doSomething() {
        $this->save();
    }

    public function save() {
        echo __METHOD__;
    }
}

$entry = new Entry();
$entry->doit();

~ $ php -v
PHP 5.6.29 (cli) (built: Dec  9 2016 07:03:56)
Copyright (c) 1997-2016 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2016 Zend Technologies

~ $ php -d error_reporting=0 Entry.php
Sample\Entry::save
~ $ php -d error_reporting=0 Entry.php | cowsay
 ____________________
< Sample\Entry::save >
 --------------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

~ $ ./echo-sd --stress \  \  Entry「もしかして……」 Model「私たち………」 「「入れ替わってるーーー！！！」」 | tail -n 7
Entry「もしかして……」
　　　　↘
　　　Model「私たち………」
　　　　↙
＿人人人人人人人人人人人人人人人人人人人＿
＞　「「入れ替わってるーーー！！！」」　＜
￣Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^￣

これが言いたいだけだった。（ネタ元）

安心してください。staticキーワードがないメソッドの静的呼び出しで警告は出ます。

~ $ php Entry.php
PHP Deprecated:  Non-static method Sample\Model::doSomething() should not be called statically, assuming $this from incompatible context in /Users/user1/Entry.php on line 7

Deprecated: Non-static method Sample\Model::doSomething() should not be called statically, assuming $this from incompatible context in /Users/user1/Entry.php on line 7
Sample\Entry::save%

PHP7ならそもそも実行できない。

~ $ brew unlink php56
Unlinking /usr/local/Cellar/php56/5.6.29_5... 17 symlinks removed

~ $ brew link php71
Linking /usr/local/Cellar/php71/7.1.0_11... 39 symlinks created


~ $ php Entry.php
PHP Deprecated:  Non-static method Sample\Model::doSomething() should not be called statically in /Users/user1/Entry.php on line 7

Deprecated: Non-static method Sample\Model::doSomething() should not be called statically in /Users/user1/Entry.php on line 7
PHP Fatal error:  Uncaught Error: Using $this when not in object context in /Users/user1/Entry.php:17
Stack trace:
#0 /Users/user1/Entry.php(7): Sample\Model::doSomething()
#1 /Users/user1/Entry.php(26): Sample\Entry->doit()
#2 {main}
  thrown in /Users/user1/Entry.php on line 17

Fatal error: Uncaught Error: Using $this when not in object context in /Users/user1/Entry.php:17
Stack trace:
#0 /Users/user1/Entry.php(7): Sample\Model::doSomething()
#1 /Users/user1/Entry.php(26): Sample\Entry->doit()
#2 {main}
  thrown in /Users/user1/Entry.php on line 17