How to omit passing defaulted arguments?

Anon

<?php
function testme($foo="default val", &$baz) {
$baz = "new return val";
print ("$foo\n"); }

$retvar="return var";
testme(null, $retvar);
testme($empty, $retvar);
print "$retvar \n";
?>

I have situations where I want to skip explicitely passing in
a value to an argument that will be defaulted anyway.
OK, so I'm lazy, but maybe it will be a pain in the neck to
look up or construct the value.
In the example above, I would like to just pass in a null or
empty placeholder so that $foo will be set to "defaul val".
Is there any way to accomplish this? The two attempts
above don't work. In VBA I would just omit the argument
and put a comma as a placeholder (e.g. testme(, $retvar)).

Thanks,
Csaba

lawnmowerman

I'm not 100% sure, but I believe that optional arguments must be placed at the end of the argument list.

Try changing your function declaration to:

function testme( &$baz, $foo="default val" )

Hope this helps and I hope I'm not way off base on this 🙂

-Rich

kparker

Default parameters must be at the end of your parameter list for this to work properly. (Think C++). Is is possible for you to reorder them?

However, in the case of the function here, you don't even need baz since it would be better to make it be the return value of the function.

Anon

<?php
function testme($foo="default val", $foo2="default 2") {
print ("$foo\n"); }

testme(null, "Howdy");
testme($empty, "Hello");
testme("Wow", "Hello");
?>

I'd like to clarify my question. The issue is that you could have
several "optional" (defaulted) variables (at the end of the argument
list) and it may not be convenient to compute the values of all of
them out to the last one that will have a value different from its
default (after all, isn't the whole point of defaults to avoid doing
this precomputation?).

           Csaba

lawnmowerman

If you read the manual page regarding default values, I think you'll agree that you'll have to determine some other method of calling your function and/or filling your values.

http://www.phpbuilder.com/manual/functions.arguments.php#functions.arguments.default

This URL states:
"Note that when using default arguments, any defaults should be on the right side of any non-default arguments; otherwise, things will not work as expected."

You could pass an array (name or numerically indexed) to the function.

<?php

function reset_params()
{
$params = array( 'foo1' => 'foo', 'foo2' => 'bar' );
return $params;
}

function testme($foo)
{
print $foo[foo1] . "\n";
print $foo[foo2] . "\n";
}

$arglist = reset_params();

testme( $arglist );

Will print:

foo

bar

$arglist[foo1] = 'fu';

testme( $arglist );

Will print:

fu

bar

$arglist = reset_params();

$arglist[foo2] = 'barians';

testme( $arglist );

Will print:

foo

barians

This isn't a very elegant way of doing things, but it does get the job done.

You could do the same thing with classes...

-Rich

Anon

You could just pass dummy values and check and handle those inside the function itself.