更好地管理功能之间的“消息”？

Question

I my framework I have some functions that when done they can add some messages to a queue for reporting.

Example: I have a function that takes a path of a photo and

• if the image is not .jpg it converts it to .jpg
• if the image is greater than 500kB it reduces its size

I have a global $msgQueue=array(); and whenever all the logic of the page is done, in my template I echo to the users all the reports (that the functions could add during the exectuion).

In that case 2 messages would be added to $msgQueue:

• The image was PNG and has been converted to JPG
• The image was 2000x1000 and now is 1000x500

But this kind of behaviour I think it's not standard. If I want share with someone one of my function (in this case is checkImage($path) ) It can't work because the functions needs that global array to put their report msgs.

Is there a standard approach to solve this so I can share my functions with someone else and don't worry about this dependence?

Answer 1

My suggestion would be to use a class, something like:

class Report(){
    public $msgQueue;

    function addReport($string){ 
         array_push($this->msgQueue, $string);  //store new report
    }

    function showReports(){
         //loop over the message queue
         ...
    }
}

Benefits:

1. You could have different kind of reports using the same class, separating process from errors for example, $processes = new Report and $errors = new Report

2. No need to declare vars as globals, the class preserves the value of its property $msgQueue you would only need to $processes->addReport("Resizing image to XXX")

3. The benefits of OOP, having a logical structure, etc.

Answer 2

I don't really think there is a standard approach. What I do is this:

• Give each library (Image, File, etc..) its own message array.

• Use a Message library that has its own message array as well as an array of "sources" that can be built/added to via Message::addSource($class, $propertyName) . (I add a message source right after I make an instance of a library, such as Image).

  • When Message::render() is executed, it combines each source's messages with the Message class's own message then renders them.

Doing it that way allows each library to be independent of others while still being able have both a per-instance and global message array.

Answer 3

Is there a standard approach to solve this?

Yes, its called OOP :) (see amosrivera 's answer for that).

But if OOP is not an option (but you should seriously consider it nonetheless), then refactoring the functions to accept a messageQueue argument (and passing it by reference) might work.

// passing $messageQueue by reference by prepending &
function checkImage( $path, array &$messageQueue = null )
{
    /* do image checking */
    $result = /* the result of the image checking */;

    // if $messageQueue argument is provided
    if( $messageQueue !== null )
    {
        // add the message to the queue
        $messageQueue[] = 'Image checking done';
    }

    return $result; // false or true perhaps.
}

Usage:

$messageQueue = array();

if( checkImage( $somePath, $messageQueue ) )
{
    echo 'checking image succeeded';
}
else
{
    echo 'checking image failed';
}

var_dump( $messageQueue );

// would output something like:
Array(1) (
    'Image checking done'
)