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Date: Wed, 18 Apr 2012 12:30:53 +0100
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To: Lester Caine <lester@lsces.co.uk>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] skipping optional parameters
From: admacedo@gmail.com (Daniel Macedo)

I am sorry Lester, but you seem to be getting the "optional parameter"
backwards.

You are supposed to use the optional parameters when it's up to the
library/function definition to determine it's value, not when the
value is what you want for this particular function call!

What you seem to be currently reading from a function definition when
using it is i.e.: "This parameter's default is TRUE? That's what I
need it to be here, skip typing it!"
This is the wrong approach for proper design, and you will have a lot
of headaches when refactoring!

If you use them *properly*, what you read when using the function call
is "I don't need/want to change the default value for this optional
parameter, use what the library determines!", this is the proper way
to use a function call with optional parameters, that will give you a
LOT less headaches!


The problem with the way things work currently, is that the default
value, is now *hard coded* into all function calls were you wanted to
use the default, but needed to define a latter optional parameter!

Hence the proper use would be to either use a reserved word, or having
named parameters.
I personally think there's a place for having both.



> Daniel Macedo wrote:
>>
>> function fn1($a =3D false, $b =3D nul, $c =3D 1)
>> {
>> =A0 var_dump($a, $b. $c);
>> }
>>
>> // your idea
>> fn1(NULL, NULL, 10), // NULL, NULL, 10
>>
>> // vs. using a reserved word
>> fn1(default, default, 10), // FALSE, NULL, 10
>
>
> Of cause one little problem here is if the default gets changed in the
> 'library' then every use of 'default' would need to be checked.
> Of cause the same problem applies with changing defaults that are used by
> leaving out the latter parameters on the list, but this just adds another
> area that needs cross checking. Always including the parameters needed is
> the safe way in many cases anyway! So leaving them off can be bad practic=
e
> anyway?
>
>
> --
> Lester Caine - G8HFL
> -----------------------------
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