A bit confused with the following code

Question

I'm attempting to learn codeigniter for php and I've come across this block of code where it seems the instructor is trying to change a constant variable. First I'm clueless as to why the curly braces are used and then I'm curious as to exactly what is going on with that constant variable.

<?php
    class MY_Model extends CI_Model {
        const DB_TABLE = 'abstract';
        const DB_TABLE_PK = 'abstract';

        private function insert() {
            $this->db->insert($this::DB_TABLE, $this);
            $this->{$this::DB_TABLE_PK} = $this->db->insert_id();
        }
    }
?>

Can someone please explain not only the use of curly braces here, but also how it's possible to assign a new value to the defined constant?

These answers may help: http://stackoverflow.com/a/9056123/1438393 , http://stackoverflow.com/questions/1147937/ — Amal Murali, Oct 01 '13 at 21:45

score 1 · Accepted Answer · answered Oct 01 '13 at 21:53

1

They're not assigning to a constant. They're using the constant as a lookup key, to create a "dynamic" attribute of the object.

This line:

$this->{$this::DB_TABLE_PK} = $this->db->insert_id();

boils down to

$this->{'abstract'} = $this->db->insert_id();

which is a perfectly acceptable construct. It's just creating an object attribute on-the-fly.

answered Oct 01 '13 at 21:53

Marc B

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Ah I should have remembered this from my basic php schooling. Thanks guys :P – Highspeed Oct 01 '13 at 22:02

A bit confused with the following code

1 Answers1