Re: Class constants
| From: | Gary . | Date: | Mon, 19 Apr 2010 14:29:18 +0000 |
| Subject: | Re: Class constants | ||
| References: | 1 2 3 4 5 | Groups: | php.general |
| Request: | Send a blank email to php-general+get-304215@lists.php.net to get a copy of this message | ||
On Mon, Apr 19, 2010 at 3:12 PM, Ashley Sheridan wrote:
> On 19 April 2010 14:24, Gary wrote:
> > Okay. Why not?
...
> Class constants must be defined with static values, not variables. They are constants after
> all! If they relied on the value of a variable, surely that would mean that their own value might
> change, so they would just become regular variables not constants.
Right. But in fact the only referenced values are *also* constant
(unless I'm completely misunderstanding the use of 'const'), so I
think it's a valid thing to want to do. I accept it doesn't seem to be
possible, I'm now curious as to the thinking behind it.
> Is there a specific reason that you need to try and achieve this?
Okay, well here's a more meaningful situation, perhaps:
class SomeTable
{
const TABLE_NAME = 'mytable';
const SELECT = 'SELECT * FROM ' . MyTable::TABLE_NAME;
const INSERT = 'INSERT INTO ' . MyTable::TABLE_NAME ...
If the table name should change for some reason, it is preferable to
make the change in one place in the code (i.e. the value of
TABLE_NAME), surely, than changing the name in the alternative, which
is something like:
class SomeTable
{
// const TABLE_NAME = 'mytable';
const SELECT = 'SELECT * FROM mytable';
const INSERT = 'INSERT INTO mytable...