PHP Calling dynamic functions

Question

Im trying to figure out how to call functions based on what a user clicks on a form. But im not sure if im doing it right.

I have a number of classes, lets say 3 for different ways to connect to a site, the user clicks on which one they would like.

FTP
SFTP
SSH

Which i have named 'service' in my code.

I don't want to run a whole bunch of IF statements, i would rather try and build the call dynamically.

What i have at the moment is as follows

$ftp_backup = new FTPBackup;
$sftp_backup = new SFTPBackup;
$ssh_backup = new SSHBackup;

$service = $request->input('service') . '_backup';
$service->testConn($request);

Im getting the following error

Call to a member function testConn() on string

Im not sure im doing this right.

Any help would be greatly appreciated.

Thanks

Rudolf Ratusiński · Accepted Answer · 2016-10-26 08:42:21Z

5

First of all $service is a string on which You cannot call method, because it is not an object (class instance).

I think it is a great example of where You can use Strategy Pattern which look like that:

class BackupStrategy {
    private $strategy = null; 

    public function __construct($service_name) 
    {
        switch ($service_name) {
            case "ftp": 
                $this->strategy = new FTPBackup();
            break;
            case "sftp": 
                $this->strategy = new SFTPBackup();
            break;
            case "ssh": 
                $this->strategy = new SSHBackup();
            break;
        }
    }

    public function testConn()
    {
      return $this->strategy->testConn();
    }
}

And then in place where You want to call it You call it by:

$service = new BackupStrategy($request->input('service'));
$service->testConn($request);

I suggest You to read about Design Patterns in OOP - it will help You a lot in the future.

edited Oct 26, 2016 at 8:42

answered Oct 26, 2016 at 7:40

Rudolf Ratusiński

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5 Comments

BigJobbies Over a year ago

This is perfect .. It seems to simplify things beyond belief for me ... I have been studying SOLID principles a bit ... Thank you

Rudolf Ratusiński Over a year ago

You're welcome :) If You find it useful You may accept is as an answer.

BigJobbies Over a year ago

Just one more thing if you dont mind ... Every *Backup() class implements an interface ... would this BackupStrategy just be a standalone class, or would i slot it in somewhere

Rudolf Ratusiński Over a year ago

Yes, it can be standalone because interface implementing is job dedicated and known only to each *Backup class. BackupStrategy class is only responsible for choosing proper *Backup class.

BigJobbies Over a year ago

This has opened up my eyes to a whole other way of coding ... I really really appreciate this!

Lionel Chan · Accepted Answer · 2016-10-26 07:41:04Z

0

How about this:

$ftp_backup = new FTPBackup;
$sftp_backup = new SFTPBackup;
$ssh_backup = new SSHBackup;

$service = $request->input('service') . '_backup';
${$service}->testConn($request);

This is called "Variables variable": http://php.net/manual/en/language.variables.variable.php

answered Oct 26, 2016 at 7:41

Lionel Chan

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Comments

aleksejjj · Accepted Answer · 2016-10-26 07:45:30Z

0

// Create class name
$className = $request->get('service') . '_backup';

// Create class instance
$service = new $className();

// Use it as you want
$service->testConn($request);

answered Oct 26, 2016 at 7:45

aleksejjj

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