PHP 7入門：函數的增強

{"type":"doc","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"本文要點"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"要在運行時創建命名的數組常量，我們可以使用新的"},{"type":"codeinline","content":[{"type":"text","text":"define()"}]},{"type":"text","text":"函數。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"要將對象作用域綁定到一個變量並調用它，我們可以使用新的"},{"type":"codeinline","content":[{"type":"text","text":"Closure::call()"}]},{"type":"text","text":"函數。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"要通過傳統的"},{"type":"codeinline","content":[{"type":"text","text":"assert()"}]},{"type":"text","text":"使用表達式和\/或自定義"},{"type":"codeinline","content":[{"type":"text","text":"AssertionError"}]},{"type":"text","text":"，那麼我們可以使用expectation。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"PHP 7支持從Generator函數返回一個值。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"PHP 7支持將一個Generator函數委託給另一個Generator函數。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"對於整數除法，使用名爲"},{"type":"codeinline","content":[{"type":"text","text":"intdiv()"}]},{"type":"text","text":"的新函數。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"要覆蓋"},{"type":"codeinline","content":[{"type":"text","text":"php.ini"}]},{"type":"text","text":"中的會話配置的設置，可以使用新的"},{"type":"codeinline","content":[{"type":"text","text":"session_start"}]},{"type":"text","text":"函數。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"要使用回調執行正則表達式搜索和替換，使用新的函數"},{"type":"codeinline","content":[{"type":"text","text":"preg_replace_callback_array()"}]},{"type":"text","text":"。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"PHP 7能夠生成加密安全的整數和字節。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"PHP 7.1支持將回調轉換爲閉包。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"箭頭（=>）函數爲匿名函數提供了簡潔的語法。"}]}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在"},{"type":"link","attrs":{"href":"https:\/\/www.infoq.com\/articles\/php7-new-type-features\/","title":"","type":null},"content":[{"type":"text","text":"PHP 7系列前面的文章中"}]},{"type":"text","text":"，我們討論了PHP類型系統的新特性。在本文中，我們將會探討PHP 7在函數方面的改善。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"PHP支持多種類型的函數，包括用戶自定義函數、內部函數、變量函數以及匿名函數。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"定義數組常量的新函數"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"PHP 7.0添加了名爲"},{"type":"codeinline","content":[{"type":"text","text":"define()"}]},{"type":"text","text":"的新函數，用來在運行時定義命名的數組常量。define()的語法如下所示："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"bool define ( string $name , mixed $value [, bool $case_insensitive = FALSE ] )"}]},{"type":"text","text":""}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"表1討論了該函數的參數"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":""},{"type":"text","marks":[{"type":"strong"}],"text":"表1 define()函數的參數"},{"type":"text","text":""}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"embedcomp","attrs":{"type":"table","data":{"content":"

參數

描述

name

常量的名稱。這個名稱可以是保留字，但不建議這樣做。

value

常量的值。這個值必須是一個標量值（整型、浮點、字符串、布爾值或NULL）或數組。

case_insensitive

常量是否區分大小寫，默認是區分大小寫的。在PHP 7.3.0中，不推薦採用不區分大小寫的方式。"}}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"創建PHP腳本_constant.php_並定義名爲"},{"type":"codeinline","content":[{"type":"text","text":"CONSTANT"}]},{"type":"text","text":"的常量，如下所示。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"define(\"CONSTANT\", \"Hello PHP\");"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我們還可以使用"},{"type":"codeinline","content":[{"type":"text","text":"const"}]},{"type":"text","text":"關鍵字來定義常量："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"const CONSTANT_2 = 'Hello php';\nconst Constant = 'HELLO PHP';\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"define()"}]},{"type":"text","text":"函數可以用來定義數組常量："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"define(\"Catalog\", ['Oracle Magazine','Java Magazine']);"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"數組常量的值可以使用數組元素訪問的方式進行輸出。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"echo Catalog[0]\necho Catalog[1]\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"_constant.php_文件如下所示："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"\"; \nconst CONSTANT_2 = 'Hello php';\necho CONSTANT_2.\"
\";\nconst Constant = 'HELLO PHP';\necho Constant.\"
\";\ndefine(\"Catalog\", ['Oracle Magazine','Java Magazine']);\necho Catalog[0].\"
\";\necho Catalog[1]\n?>\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"運行腳本將會輸出腳本中定義的常量值。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"Hello PHP\nHello php\nHELLO PHP\nOracle Magazine\nJava Magazine\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"全局定義的常量，如"},{"type":"codeinline","content":[{"type":"text","text":"TRUE"}]},{"type":"text","text":"或"},{"type":"codeinline","content":[{"type":"text","text":"FALSE"}]},{"type":"text","text":"，不能進行重定義。爲了闡述這一點，我們創建一個_const.php_腳本，該腳本定義了常量"},{"type":"codeinline","content":[{"type":"text","text":"TRUE"}]},{"type":"text","text":"，並將它的值設置成了"},{"type":"codeinline","content":[{"type":"text","text":"20"}]},{"type":"text","text":"："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果你運行該腳本的話，它將會輸出的值是"},{"type":"codeinline","content":[{"type":"text","text":"1"}]},{"type":"text","text":"，這也是"},{"type":"codeinline","content":[{"type":"text","text":"TRUE"}]},{"type":"text","text":"全局定義的值。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"綁定對象作用域到閉包的新函數"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"閉包是用來表示匿名函數的類。PHP 7.0引入了新的"},{"type":"codeinline","content":[{"type":"text","text":"Closure::call()"}]},{"type":"text","text":"函數，能夠非常簡便地將對象作用域臨時綁定到一個閉包並調用它。爲了闡述這一點，創建腳本_closure.php_並複製如下清單所示的代碼："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"getMsg();};\necho $getMsg->call(new Hello);\n?>\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在上述腳本中，Hello是一個具有函數"},{"type":"codeinline","content":[{"type":"text","text":"getMsg()"}]},{"type":"text","text":"的類。"},{"type":"codeinline","content":[{"type":"text","text":"Closure::call()"}]},{"type":"text","text":"函數用來創建一個"},{"type":"codeinline","content":[{"type":"text","text":"Hello"}]},{"type":"text","text":"實例，並綁定它的作用域到一個調用"},{"type":"codeinline","content":[{"type":"text","text":"getMsg"}]},{"type":"text","text":"方法的閉包。運行該腳本將會輸出"},{"type":"codeinline","content":[{"type":"text","text":"Hello"}]},{"type":"text","text":"消息。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"Expectation"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在討論_expectation_之前，我們先看一下傳統的斷言。傳統的"},{"type":"codeinline","content":[{"type":"text","text":"assert()"}]},{"type":"text","text":"方法定義如下所示。它會檢查如果代碼的預期值（稱爲_斷言_）是不是爲"},{"type":"codeinline","content":[{"type":"text","text":"FALSE"}]},{"type":"text","text":"，如果是"},{"type":"codeinline","content":[{"type":"text","text":"FALSE"}]},{"type":"text","text":"的話，它會打印出描述消息，並且默認會中止程序。如果斷言不是"},{"type":"codeinline","content":[{"type":"text","text":"FALSE"}]},{"type":"text","text":"的話，"},{"type":"codeinline","content":[{"type":"text","text":"assert()"}]},{"type":"text","text":"沒有任何效果。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"bool assert ( mixed $assertion [, string $description ] )"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"按照設計，斷言用於開發和測試期的調試，而不是運行期的操作。"},{"type":"codeinline","content":[{"type":"text","text":"assert()"}]},{"type":"text","text":"的行爲可以通過"},{"type":"link","attrs":{"href":"https:\/\/www.php.net\/manual\/en\/function.assert-options.php","title":"","type":null},"content":[{"type":"text","text":"assert_options()"}]},{"type":"text","text":"或者"},{"type":"codeinline","content":[{"type":"text","text":".ini"}]},{"type":"text","text":"文件進行配置。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"傳統上，"},{"type":"codeinline","content":[{"type":"text","text":"assert()"}]},{"type":"text","text":"的第一個參數應該是一個要評估計算的字符串或者作爲斷言進行測試的boolean條件。如果所提供的是一個字符串的話，它會以PHP代碼的形式進行評估計算。如果所提供的是一個boolean條件的話，那麼在傳遞給"},{"type":"codeinline","content":[{"type":"text","text":"assert_options()"}]},{"type":"text","text":"定義的斷言回調函數（如果存在的話）之前，它將會被轉換成字符串。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"斷言在PHP 7中進行了徹底修改，現在被稱爲_expectation_，並且"},{"type":"codeinline","content":[{"type":"text","text":"assert()"}]},{"type":"text","text":"是PHP 7中的一個語言結構。作爲對"},{"type":"codeinline","content":[{"type":"text","text":"assert()"}]},{"type":"text","text":"的增強，expectations被添加了進來，並且具有如下的語法："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"bool assert ( mixed $assertion [, Throwable $exception ] )"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"有了expectations之後，"},{"type":"codeinline","content":[{"type":"text","text":"assert()"}]},{"type":"text","text":"的第一個參數可能是會返回一個值的表達式，而不再是一個要評估執行的PHP代碼字符串或者要測試的boolean條件。表達式會被執行，得到的結果會被用來確定斷言是否成功。從PHP 7開始，使用字符串作爲第一個參數已經被廢棄掉了。"},{"type":"codeinline","content":[{"type":"text","text":"assert_options()"}]},{"type":"text","text":"依然能夠與expectations協同使用，但是並不推薦這麼做。相反，我們應該使用兩個新的php.ini配置指令，如表2所示。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"表2 Expectations的配置指令"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"embedcomp","attrs":{"type":"table","data":{"content":"

配置指令

類型

描述

支持的值

默認值

zend.assertions

integer

配置是否要生成斷言代碼並運行。

1：生成和運行斷言代碼（開發模式）** 0：生成斷言代碼但是並不會在運行時執行 **-1：不生成斷言代碼（生產模式）。使用該配置以便於使用expectations。

1

assert.exception

對於失敗的斷言拋出AssertionError或自定義異常

1：當斷言失敗的時候，要麼拋出以異常的形式提供的對象，要麼在沒有提供異常的情況下拋出一個新的AssertionError對象。使用該配置以便於使用expectations。** **0：使用或生成上述的Throwable，但是隻生成一個告警，而不拋出異常或AssertionError。

0"}}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"藉助expectations，第二個參數可能會是一個"},{"type":"codeinline","content":[{"type":"text","text":"Throwable"}]},{"type":"text","text":"對象，而不再是字符串描述。爲了在斷言失敗的時候拋出"},{"type":"codeinline","content":[{"type":"text","text":"Throwable"}]},{"type":"text","text":"對象或異常，"},{"type":"codeinline","content":[{"type":"text","text":"assert.exception"}]},{"type":"text","text":"指令必須設置爲1。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"相對於傳統的斷言，expectations有如下的優勢，不過爲了向後兼容，傳統的斷言依然是支持的："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"可以用表達式來評估一個斷言，而不是字符串或boolean值。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通過使用"},{"type":"codeinline","content":[{"type":"text","text":"php.ini"}]},{"type":"text","text":"設置，斷言代碼即便已經生成，但可以在運行期跳過它們。甚至可能根本就不生成斷言代碼，對於生產環境的使用來說，推薦這樣做。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"可以拋出自定義異常。PHP 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替換完成的數量，存儲在$count變量中。"}}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"爲了闡述這個新的功能，創建樣例腳本"},{"type":"text","marks":[{"type":"italic"}],"text":"prereg.php"},{"type":"text","text":"並複製如下的代碼清單到腳本中。主題或要搜索的樣例字符串設置成了'AAaaaaa Bbbbb'。"},{"type":"codeinline","content":[{"type":"text","text":"patterns_and_callbacks"}]},{"type":"text","text":"參數設置成了尋找匹配'A'和'b'的數量。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":" function ($match) {\n echo strlen($match[0]), ' matches for \"A\" found', PHP_EOL;\n },\n '~[b]+~i' => function ($match) {\n echo strlen($match[0]), ' matches for \"b\" found', PHP_EOL;\n }\n ],\n $subject\n);\n?>\n\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果運行腳本的話，匹配'A'和'b'的數量將會被打印出來："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"7 matches for \"A\" found 5 matches for \"b\" found"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"生成加密安全的整數和字節的新函數"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"新增了兩個生成加密安全的整數和字節的新函數。這些函數在表4中進行了討論。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":""},{"type":"text","marks":[{"type":"strong"}],"text":"表4 新的加密函數"},{"type":"text","text":""}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"embedcomp","attrs":{"type":"table","data":{"content":"

函數	語法	參數	返回值	描述
random_bytes()	string random_bytes ( int $length )	int類型的$length，代表了以字節形式返回的任意字符串的長度。	返回一個字符串，其中包含了所請求數量的加密安全的隨機字節。	生成和返回一個任意的字符串，包含了加密的隨機字節。
random_int()	int random_int ( int $min , int $max )	$min參數指定了返回值的下限，它必須等於或高於PHP_INT_MIN。$max參數指定了返回值的上限，它必須等於或低於PHP_INT_MAX。	加密的安全整數，這個數介於$min和$max之間。	生成和返回加密的任意整數。"}}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"作爲樣例，我們創建一個名爲"},{"type":"text","marks":[{"type":"italic"}],"text":"random_int.php"},{"type":"text","text":"的腳本，它會生成加密的任意整數。首先，生成一個範圍在1和99之間的整數，然後生成一個範圍在-100到0的整數。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果運行腳本的話，將會打印出兩個整數。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"int(98) int(-84)"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"生成的整數是隨機的，如果相同的腳本再次運行的話，很可能會生成兩個不同的整數。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"接下來，創建另外一個樣例腳本"},{"type":"text","marks":[{"type":"italic"}],"text":"random_bytes.php"},{"type":"text","text":"，它會生成加密的任意字節，其長度爲10。然後，我們使用"},{"type":"codeinline","content":[{"type":"text","text":"bin2hex"}]},{"type":"text","text":"函數將任意的字節轉換成ASCII字符串，其中包含了所返回字節的16進制字符串形式。複製如下的代碼清單到腳本文件中："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"運行腳本並生成加密的任意字節："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"string(20) \"ab9ad4234e7c6ceeb70d\""}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"list()函數的修改"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"list()"}]},{"type":"text","text":"函數用來爲一個變量列表像數組那樣進行賦值。PHP 7.0和7.1爲list()帶來了一些變更。在PHP 7中，"},{"type":"codeinline","content":[{"type":"text","text":"list()"}]},{"type":"text","text":"無法像之前的版本那樣解包字符串，如果對字符串進行解包的話，將會返回"},{"type":"codeinline","content":[{"type":"text","text":"NULL"}]},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在PHP 5.x中，使用"},{"type":"codeinline","content":[{"type":"text","text":"list()"}]},{"type":"text","text":"解包一個字符串的時候，會將"},{"type":"codeinline","content":[{"type":"text","text":"list()"}]},{"type":"text","text":"中的一個變量賦值爲字符串中的值。我們使用PHP 5.x中的"},{"type":"codeinline","content":[{"type":"text","text":"list()"}]},{"type":"text","text":"來闡述解包字符串。創建腳本_list.php_並複製如下的代碼清單到腳本中。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果運行該腳本的話，與前面的腳本類似，我們會看到輸出的值是"},{"type":"codeinline","content":[{"type":"text","text":"NULL"}]},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"實際上，在PHP 7.x中，如果"},{"type":"codeinline","content":[{"type":"text","text":"list()"}]},{"type":"text","text":"要通過字符串進行賦值，那麼必須要使用"},{"type":"codeinline","content":[{"type":"text","text":"str_split"}]},{"type":"text","text":"函數："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果運行該腳本的話，不會生成錯誤，並且會創建一個具有兩個非空元素和一個空元素的列表。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"Oracle Magazine latest edition is January-February 2018."}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"list()"}]},{"type":"text","text":"函數的另外一個修改就是按照變量定義的順序爲其進行賦值。在此之前，值是按照與定義相反的順序進行賦值的。爲了闡述之前的行爲，使用PHP 5.x運行如下的"},{"type":"text","marks":[{"type":"italic"}],"text":"list.php"},{"type":"text","text":"中的程序清單："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我們可以探測腳本的輸出（參見圖1），值是按照定義相反的順序進行賦值的。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https:\/\/static001.infoq.cn\/resource\/image\/bf\/a5\/bf5138105c09a1c0ccd0f3cba53297a5.png","alt":null,"title":"","style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":"","fromPaste":false,"pastePass":false}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":"center","origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"圖1 值是按照相反的順序賦值的"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在PHP 7.0上運行相同的腳本，我們會發現_list()_會按照與定義相同的順序爲變量賦值："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"array(3) { [0]=> string(1) \"A\" [1]=> int(2) [2]=> int(3) }"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"PHP 7.1.0支持在列表中指定key以表明賦值的數字順序。作爲樣例，創建"},{"type":"text","marks":[{"type":"italic"}],"text":"list.php"},{"type":"text","text":"腳本幷包含如下的代碼清單。注意，在本例中，所有的key都是數字："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":" $journal, 1=> $publisher, 2 => $edition) = ['Oracle Magazine', 'Oracle Publishing', 'January February 2018'];\necho \"$journal, $publisher, $edition. \\n\";\n?>\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果運行腳本的話，將會得到如下的列表值："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"Oracle Magazine, Oracle Publishing, January February 2018."}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"賦值的數字順序可以交叉，如下面的代碼清單所示，索引0放在了索引1的後面。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":" $journal, 0=> $publisher, 2=>$edition) = ['Oracle Magazine', 'Oracle\nPublishing', 'January February 2018'];\necho \"$journal, $publisher,$edition \\n\";\n?>\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果運行腳本的話，輸出的值表明變量是根據數字的key進行賦值的，而不是列表中key的順序。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"Oracle Publishing, Oracle Magazine,January February 2018"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"key的索引可以使用單括號或雙括號括起來，如下所示："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":" $journal, '0'=> $publisher, '2'=>$edition) = ['Oracle Magazine', 'Oracle\nPublishing', 'January February 2018'];\necho \"$journal, $publisher,$edition \\n\";\n?>\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"上述腳本會生成與前面的腳本相同的輸出。如果在"},{"type":"codeinline","content":[{"type":"text","text":"list()"}]},{"type":"text","text":"中某個元素使用了key，那麼它的所有元素都應該使用key。例如，創建一個列表，有些元素使用了key進行賦值，有些元素沒有使用key："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":" $journal, 1=> $publisher, 2) = ['Oracle Magazine', 'Oracle Publishing', 'January February 2018'];\necho \"$journal, $publisher. \\n\";\n?>\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果運行該腳本的話，我們會看到一個錯誤信息，提示在賦值的時候，帶有key和不帶key的數組條目不能混合使用："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"Cannot mix keyed and unkeyed array entries in assignments"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"字符串偏移支持負數"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"從PHP 7.1開始，像"},{"type":"codeinline","content":[{"type":"text","text":"strpos"}]},{"type":"text","text":"和"},{"type":"codeinline","content":[{"type":"text","text":"substr"}]},{"type":"text","text":"這樣的字符串操作函數引入了對負數偏移量的支持，也就是從字符串的結尾處開始處理偏移。使用[]和{}的字符串索引也支持負數偏移量。例如，\"ABC\"[-2]將會返回字母'B'。現在，我們創建一個腳本"},{"type":"text","marks":[{"type":"italic"}],"text":"str-negative-offset.php"},{"type":"text","text":"並複製如下的代碼清單到腳本中："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"\";\necho strpos(\"aabbcc\", \"a\", -6);\necho \" \";\necho strpos(\"abcdef\", \"c\", -1);\necho \" \";\necho strpos(\"abcdef\", \"c\", -5);\necho \" \";\necho substr(\"ABCDEF\", -1); \necho \" \"; \necho substr(\"ABCDEF\", -2, 5); \necho \" \";\necho substr(\"ABCDEF\", -7);\necho \" \";\necho substr(\"ABCDEF\", -6);\necho \" \";\necho substr(\"ABCDEF\", -5);\necho \" \";\necho substr(\"ABCDEF\", 6);\necho \" \";\necho substr(\"abcdef\", 1, -3); \necho \" \";\necho substr(\"abcdef\", 3, -2); \necho \" \"; \necho substr(\"abcdef\", 4, -1);\necho \" \"; \necho substr(\"abcdef\", -5, -2); \n?>\n\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"該腳本提供了多個在字符串函數和[]中使用負數偏移量的樣例。如果運行腳本的話，它將會輸出："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"F\n0\n\n2\nF\nEF\nABCDEF\nABCDEF\nBCDEF\n\nbc\nd\ne\nbcd\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"將回調轉換成閉包的新函數"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"閉包用來以字符串變量的形式傳遞函數（用戶自定義的函數以及除語言構造之外的內置函數）和方法。例如，函數"},{"type":"codeinline","content":[{"type":"text","text":"hello()"}]},{"type":"text","text":"可以以參數的形式傳遞給另外一個函數，或者使用函數名字以字符串的形式從另外一個函數中返回，如'hello'，當然這樣做的前提是參數類型\/返回類型爲callable。我們創建一個樣例腳本"},{"type":"text","marks":[{"type":"italic"}],"text":"callable.php"},{"type":"text","text":"並聲明函數"},{"type":"codeinline","content":[{"type":"text","text":"hello()"}]},{"type":"text","text":"，該函數輸出一個‘hello’消息。聲明另外函數，其參數類型是callable。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"function 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3]);"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"ArrayIterator"}]},{"type":"text","text":"是可數的，"},{"type":"codeinline","content":[{"type":"text","text":"is_countable"}]},{"type":"text","text":"會輸出TRUE，因爲"},{"type":"codeinline","content":[{"type":"text","text":"ArrayIterator"}]},{"type":"text","text":"實現了Countable接口。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"echo is_countable(new 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countable\";\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"上述代碼片段的結果是"},{"type":"codeinline","content":[{"type":"text","text":"FALSE"}]},{"type":"text","text":"，因爲類A並沒有實現"},{"type":"codeinline","content":[{"type":"text","text":"Countable"}]},{"type":"text","text":"。如果"},{"type":"codeinline","content":[{"type":"text","text":"is_countable"}]},{"type":"text","text":"的參數是一個數組的話，那麼它將會返回"},{"type":"codeinline","content":[{"type":"text","text":"TRUE"}]},{"type":"text","text":"，如下面的代碼片段所示："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"$array=['A', 'B', 3];\nif (is_countable($array)) {\n var_dump(count($array)); \n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"本節所有的代碼片段均放到了"},{"type":"text","marks":[{"type":"italic"}],"text":"is_countable.php"},{"type":"text","text":"腳本中。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"\"; \necho is_countable(new ArrayIterator());\necho \" \"; \nif (!is_countable(new A())) {\n echo \"Not countable\";\n}\necho \" \";\n$array=['A', 'B', 3];\nif (is_countable($array)) {\n var_dump(count($array)); \n}\n?>\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"運行該腳本，輸出如下所示："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"1\n1\nNot countable\nint(3)\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"箭頭函數"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"PHP 7.4引入了_箭頭函數_，從而使匿名函數的語法更加簡潔。箭頭函數的形式如下所示："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"fn(parameter_list) => expr"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"箭頭函數具有最低的執行優先級，這意味着箭頭 =>右邊的表達式會在箭頭函數之前執行，例如，箭頭函數"},{"type":"codeinline","content":[{"type":"text","text":"fn($x) => $x + $y"}]},{"type":"text","text":"等價於"},{"type":"codeinline","content":[{"type":"text","text":"fn($x) => ($x + $y)"}]},{"type":"text","text":"，而不是"},{"type":"codeinline","content":[{"type":"text","text":"(fn($x) => $x) + $y"}]},{"type":"text","text":"。在外圍作用域中聲明的且被表達式中使用的變量是隱式按值捕獲的。作爲樣例，考慮如下的腳本，它聲明瞭一個箭頭函數："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"codeinline","content":[{"type":"text","text":"$fn1 = fn($msg) => $msg.' '.$name;"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"變量"},{"type":"codeinline","content":[{"type":"text","text":"$name"}]},{"type":"text","text":"會自動從封閉範圍捕獲，上述的箭頭函數等價於："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"$fn2 = function ($msg) use ($name) {\n return $msg.' '.$name;\n};\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"對$x的按值綁定等價於對箭頭函數中每次出現"},{"type":"codeinline","content":[{"type":"text","text":"$x"}]},{"type":"text","text":"均執行"},{"type":"codeinline","content":[{"type":"text","text":"use($x)"}]},{"type":"text","text":"。箭頭函數還聲明瞭一個參數"},{"type":"codeinline","content":[{"type":"text","text":"$msg"}]},{"type":"text","text":"。在下一個樣例中，"},{"type":"codeinline","content":[{"type":"text","text":"var_export"}]},{"type":"text","text":"調用箭頭函數並提供一個參數，輸出值爲'Hello John'："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":" $msg.' '.$name;\nvar_export($fn1(\"Hello\"));\/\/'Hello John'\n?>\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"箭頭函數可以進行嵌套，如下面的腳本所示。外層的腳本函數按值捕獲變量"},{"type":"codeinline","content":[{"type":"text","text":"$name"}]},{"type":"text","text":"，內層的箭頭函數從外層函數捕獲"},{"type":"codeinline","content":[{"type":"text","text":"$name"}]},{"type":"text","text":"："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":" fn($msg2) => $msg1.' '.$msg2.' '.$name;\nvar_export($fn(\"Hello\")(\"Hi\")); \n?>\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"當腳本運行的時候，輸出入圖2所示。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https:\/\/static001.infoq.cn\/resource\/image\/b1\/8a\/b139ee84d00c100560193dea7a28fd8a.png","alt":null,"title":"","style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":"","fromPaste":false,"pastePass":false}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":"center","origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"圖2 箭頭函數可以進行嵌套"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"因爲箭頭函數使用按值的變量綁定，修改箭頭函數中變量的值不會影響外層作用域中的值。爲了闡述這一點，如下腳本中的箭頭函數遞減了外層代碼塊中變量"},{"type":"katexinline","attrs":{"mathString":"x的值，但是它對"}},{"type":"text","text":"x的值並沒有影響，它依然是"},{"type":"codeinline","content":[{"type":"text","text":"1"}]},{"type":"text","text":"："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":" x--; \/\/ 沒有影響\n$fn();\nvar_export($x); \/\/輸出 1\n?>\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"箭頭函數支持任意的函數簽名，可以包含參數和返回類型、默認值、可變參數以及按引用的變量傳遞和返回。如下的腳本闡述了箭頭函數不同形式簽名的使用。腳本中籤名描述和輸出通過註釋"},{"type":"codeinline","content":[{"type":"text","text":"\/\/"}]},{"type":"text","text":"進行展示。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":" $msg.' '.$name;\n\/\/包括可變參數的箭頭函數 \n$fn2 = fn(...$x) => $x;\n \/\/包括按引用參數傳遞的箭頭函數\n$fn3=fn(&$x) => $x++;\n$fn3($x);\necho $x; \/\/ 2\nvar_export($fn(\"Hello\"));\/\/'Hello John'\nvar_export($fn());\/\/'Hi John'\nvar_export($fn2(1,2,3)); \/\/array ( 0 => 1, 1 => 2, 2 => 3, ) \n?>\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"箭頭函數的對象上下文中可能會使用"},{"type":"codeinline","content":[{"type":"text","text":"$this"}]},{"type":"text","text":"。如果與帶有static前綴的箭頭函數一起使用，那麼就不能使用"},{"type":"codeinline","content":[{"type":"text","text":"$this"}]},{"type":"text","text":"。爲了闡述這一點，考慮如下的腳本，它在對象上下文和類上下文中使用了"},{"type":"codeinline","content":[{"type":"text","text":"$this"}]},{"type":"text","text":"。如果不在對象上下文中使用的話，將會輸出錯誤信息。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":" var_dump($this);\n $fn(); \/\/ object(A)#1 (0) { }\n $fn = static fn() => var_dump($this);\n $fn(); \/\/Uncaught Error: Using $this when not in object context \n \n }\n}\n$a=new A();\n$a->fn1();\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"總結"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在該系列關於PHP 7新特性的第四篇（也是倒數第二篇）文章中，我們討論了關於PHP函數的新特性。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在本系列的下一篇，也就是最後一篇中，我們將會討論關於數組、操作符、常量和異常處理方面的新特性。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"作者簡介："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"Deepak Vohra"},{"type":"text","text":"是一位Sun認證的Java程序員和Sun認證的Web組件開發人員。Deepak在WebLogic Developer's Journal、XML Journal、ONJava、java.net、IBM developerWorks、Java Developer’s Journal、Oracle Magazine和devx上都發表過Java和Java EE相關的技術文章。Deepak還出版過五本關於Docker的書，他是Docker導師。Deepak還發表了多篇關於PHP的文章，以及一本面向PHP和Java開發人員的Ruby on Rails圖書。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"原文鏈接："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"link","attrs":{"href":"https:\/\/www.infoq.com\/articles\/php7-function-improvements\/","title":"","type":null},"content":[{"type":"text","text":"Article: PHP 7 – Functions Improvements"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"相關閱讀："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"link","attrs":{"href":"https:\/\/www.infoq.cn\/article\/rZZBM2XfaaRr5JviyZqJ","title":"","type":null},"content":[{"type":"text","text":"PHP 7 入門：新特性簡介"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"link","attrs":{"href":"https:\/\/www.infoq.cn\/article\/H5av8rIy5WDy4dUagZWx","title":"","type":null},"content":[{"type":"text","text":"PHP 7 入門：類和接口的增強"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"link","attrs":{"href":"https:\/\/www.infoq.cn\/article\/hpjgR2sLTTFbTA2qcxfu","title":"","type":null},"content":[{"type":"text","text":"PHP 7 入門：數組、運算符、常量及異常處理的改進"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}}]}