PHP错误信息帮助并尝试/捕获

Question

我正在尝试创建一个函数来删除用户与常量联系人的联系。这个函数调用一个包装类来保持常量的联系，并且它可以工作，但是如果你给它一个不存在于他们网站上的电子邮件地址，它会返回一个可捕捉的致命错误。

我是第一次尝试/捕捉，而且我还不太清楚该把它放在哪里，这样我就可以创建一个优美的错误消息，而不是我正在得到的可捕捉的致命错误。下面是我的当前代码：

function ccdeleteuser($emailaddress)
{
//this code accesses the constant contact wrapper class to delete a user based on email
$ConstantContact = new ConstantContact("basic", "apikey", "usr", "pwd");
$SearchContact = $ConstantContact->searchContactsByEmail($emailaddress);
$DeleteContact = $ConstantContact->deleteContact($SearchContact[0]);  
}

$emailtotry = "test@test.com";  //this is email is NOT in Constant Contact
ccdeleteuser($emailtotry);

现在，如果我运行这个，我会得到以下错误：

传递给ConstantContact：：

Contact ()的参数1必须是联系人的实例，空给定，在第19行的路径中调用，并在第214行中定义为常量联系人包装文件

任何帮助都是非常感谢的！

Answer 1

正确的方法是首先测试null：

function ccdeleteuser($emailaddress)
{

    $ConstantContact = new ConstantContact("basic", "apikey", "usr", "pwd");
    $SearchContact = $ConstantContact->searchContactsByEmail($emailaddress);
    // first makes sure that the 0 index of of SearchContact is accessible at all
    // then it ensures that only something "truthy" will trigger delete -- this
    // means that if $SearchContact[0] is null, the function won't try to delete
    if( $SearchContact && isset( $SearchContact[0] ) && $SearchContact[0])
        $DeleteContact = $ConstantContact->deleteContact($SearchContact[0]);  
    else
        echo "Can't do nothin'"; // do something useful?
}

试着..。抓住，你可能会让它看起来像这样：

function ccdeleteuser($emailaddress)
{

    $ConstantContact = new ConstantContact("basic", "apikey", "usr", "pwd");
    $SearchContact = $ConstantContact->searchContactsByEmail($emailaddress);
    try
    {
        // keep this... it is still useful
        if( $SearchContact && isset( $SearchContact[0] ) && $SearchContact[0])
            $DeleteContact = $ConstantContact->deleteContact($SearchContact[0]);  
        else
            echo "Can't do nothin'";
    }
    catch( Exception $e )
    {
        // I'm making up a function "log" which will record that an error 
        // has taken place. It is a good idea to always log all exceptions
        // so that you don't accidentally obfuscate something important
        log( $e->getMessage() );
        // do something useful
    }
}

一般说来，最好是主动采取行动，防止出现例外情况，而不是简单地在事后抓住它们。我甚至要说，你应该把尽你所能的一切都当作一条规则，以防止出现异常的可能性，并且只使用.作为最后一种可能的手段来抓。