Accessor functions and data types

[{RainmakeR}]

Hi all,

Here's a quick question... is it a good idea to enforce the type of value that can be stored in a particular object property or attribute? i.e. the setter function forces a passed value to be an integer or a string, or perhaps verifies that the value is a particular kind of class. For example:

public function setSomething($something)
{
   $this->something = (string) $something;
} 

Is this good practice or overkill? Opinions?

Great forums by the way, glad I found them!

Cheers,

{R}

[McGruff]

Not usually necessary in php it would be rare if the code that accepts the return value was type-sensitive. You might want to force boolean type occasionally to avoid ambiguity with 0's & etc but that's not always necessary.

[arborint]

I find it is not necessary to enforce type of scalars, but I often check if the value is not a scalar and deal with it appropriately.

[MiiJaySung]

I occasionally use it. casts can look a little messy though.

I do find it handy for SQL. Many people use stupid crazy escaping methods for all of their SQL sanity checks. Often you are refering/addressing rows in your database by a primary key, or some relationship that is bound together by numeric data. In this case I like do something like ...

$sql = 'SELECT stuff FROM rubbish WHERE scank_id = '.(int)$scanky_id;

This is a nice easy way to remove injections. Some ppl in other languages do all sorts of crap like ...

$sql = 'SELECT stuff FROM rubbish WHERE scank_id = '. 0 + $scanky_id;

which I find confusing.

The other place when it is handy is when you wanna pass a parameter that is an array list for >1 item, but only use a string if there is only one thing in the list ...

function getRubbishByScankIds($ids) {
$ids = (array)$ids;
// Below I assume all the array elelements are all numbers and are from a safe datasource
$sql = 'SELECT stuff FROM rubbish WHERE scank_id IN ('.implode(', ', $ids).')';
}

as you can see this is a good way to cast strings as arrays when you are mixing strings and arrays as paramters. not many ppl know about the (array) cast (in fact I'm the only person I know who uses it!)

I only use casts where I need them. Don't use them everywhere, as it's not needed and will only slow stuff down.

[{RainmakeR}]

Thanks guys for your feedback! Much appreciated... these forums rock btw, best I've seen for 'serious' PHP programming by a long mile. ;D