[笔记]CGI&PHP

 PHP是一个很好的语言，而且有很多惊喜。而今天我看到了一个有趣的方法，在Arnold Daniels的博客。他谈到PHP中的临时变量。这个秘诀有益于"懒惰"的程序员，使程序员可以不用再去想该去给变量取个什么名字。他们可以使用这样的变量名：${0}。

我比Arnold Daniels更懒，根本就不想用变量。下面有一些技巧让你的代码更少。

1. 使用 || (or) 和 && (and) 操作代替 if.

// 标准写法
$status = fwrite($h, ''some text'');
if (!$status) {
    log(''Writing failed'');
}

// 较少的代码
${0} = fwrite($h, ''some text'');
if (!${0}) log(''Writing failed'');

// 更少的代码
fwrite($h, ''some text'') or log(''Writing failed'');

2. 使用三元运算符.

// 标准写法
if ($age < 16) {
    $message = ''Welcome!'';
} else {
  $message = ''You are too old!'';
}

// 较少的代码
$message = ''You are too old!'';
if ($age < 16) {
    $message = ''Welcome!'';
}

// 更少的代码
$message = ($age < 16) ? ''Welcome!'' : ''You are too old!'';

3. 使用for替换掉while.

// 标准写法
$i = 0;
while ($i < 100) {
  $source[] = $target[$i];
  $i += 2;
}

// 较少的代码
for ($i = 0; $i < 100; $source[] = $target[$i+=2]);

4. 很多地方是必须写变量。例如： PHP fluent API tips 。例如：一个函数调用得到一个数组，然后直接使用数组元素。

//下面这个例子会发生错误，因为函数调用，返回的数组没有先赋值给一个变量，而直接使用[''extension'']。

$ext = pathinfo(''file.png'')[''extension''];
// result: Parse error: syntax error, unexpected ''['' in ... on line ...

你可以建立一个函数来解决这个问题，如下：(相当不错的方法，看着有点别扭...)

// returns reference to the created object
function &r($v) { return $v; }
// returns array offset
function &a(&$a, $i) { return $a[$i]; }

5. 多花时间去研究php自带的函数方法，PHP有很多很有趣的方法能使你的代码更短。

6. 当写更多的代码可以使程序更清晰的时候，不要懒惰。多花时间写注释，尽量写易读的代码。这才是真正节约时间的技巧。(多写注释和易读的代码，在以后修改调试的时候会节约时间)

PHP is a good language, but there are always surprises. And today I''ve seen an interesting approach in Arnold Daniels''s blog. He talks about temporary variables in PHP. This tip is useful to "lazy" developers who do not even think about variable names. They may prefer magic names like ${0} and 0 is good enough variable name, why not...

But I''m even more lazy then Arnold and sure that when there is no variable, then there is no problem. So here are a few tips that can make your code shorter and harder to read :-)

1. Use || (or) and && (and) operations instead of if.

// A lot of code
$status = fwrite($h, ''some text'');
if (!$status) {
    log(''Writing failed'');
}

// Less code
${0} = fwrite($h, ''some text'');
if (!${0}) log(''Writing failed'');

// Even less code
fwrite($h, ''some text'') or log(''Writing failed'');

2. Use ternary operator.

// A lot of code
if ($age < 16) {
    $message = ''Welcome!'';
} else {
  $message = ''You are too old!'';
}

// Less code
$message = ''You are too old!'';
if ($age < 16) {
    $message = ''Welcome!'';
}

// Even less code
$message = ($age < 16) ? ''Welcome!'' : ''You are too old!'';

3. Use for instead of while.

// A lot of code
$i = 0;
while ($i < 100) {
  $source[] = $target[$i];
  $i += 2;
}

// less code
for ($i = 0; $i < 100; $source[] = $target[$i+=2]);

4. In some cases PHP requires you to create a variable. For example, ech the PHP fluent API tips article. Another example is getting array element when array is returned by the function.

$ext = pathinfo(''file.png'')[''extension''];
// result: Parse error: syntax error, unexpected ''['' in ... on line ...

To handle all these situation you can create a set of small functions which shortcuts frequently used operations.

// returns reference to the created object
function &r($v) { return $v; }
// returns array offset
function &a(&$a, $i) { return $a[$i]; }

5. Explore the language you use. PHP is very powerful and has a lot of functions and interesting aspects of the language which can make your code more efficient and short.

6. When it is better to write more and then read the code easily, do not be lazy. Spend a few seconds and write a comment and more readable construction. This is only a tip in this list that really can save hours, not minutes.