On 16 February 2011 21:45, Adam Richardson <simpleshot@xxxxxxxxx> wrote:
> On Wed, Feb 16, 2011 at 3:21 PM, Peter Lind <peter.e.lind@xxxxxxxxx> wrote:
>
>> On 16 February 2011 21:00, Dan Schaefer <dan@xxxxxxxxxxxxxxxxxxxx> wrote:
>> > In my code, I set the optional parameter to NULL and check for triple
>> equals
>> > "===" or "!==" to see if the variable has been passed with a value. IMO,
>> > this is the safest way.
>> >
>> > function MyFunction($x, $y, $z=NULL) {
>> > if ($z !== NULL) {
>> > // Do Something
>> > }
>> > }
>>
>> In case you're actually trying to test if a variable was passed or not
>> that doesn't work (as it doesn't detect NULL passed in). Use
>> func_get_args() as that gives you any and all arguments passed to the
>> function, excluding defaults.
>>
>
> I'm not sure what you're saying here, Peter? Are you saying that the code
> wouldn't detect if $z was set to NULL by the calling code or by the default?
> I believe the point would be that no matter the case, the check would still
> perform the same task.
>
> Maybe I misunderstood (sorry.)
The point is the poster seemed to suggest the safest way to use
optional parameters was to use null as the default value and use ===
null to check against the optional parameter - as a way to check if
anything was passed in or not. I just pointed out that that would fail
to check for a null passed in and that func_get_args() would be a
better match. You're obviously right that the check inside the
function would work the same whether null was passed in or the value
was defaulted to null.
>
>>
>> That said, if you're making use of optional parameters and need to
>> check if anything was passed in, you're almost certainly doing things
>> wrong.
>>
>
> I sometimes use this approach. PHP doesn't to my knowledge allow you to use
> function calls within defaults. There are times that I want the default to
> be the result of a function, and to accomplish this, I'll often set the
> default to null, then check for the null and carry out the function within.
>
> Is there a better solution?
As noted in the post, func_get_args will show any and all (at least on
my 5.3.3 install and 5.2.6 install) values passed in to the function -
hence it will also show if no parameter was passed in (and is thus
safer than relying on the default value).
That noted, I don't think checking if a value was passed in is good
design - I think the function should be ignorant of what is passed to
it. But that's just me :)
Regards
Peter
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