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Proposal: Dangling comma in function call parameters

php.internals

Christian Schneider

22 years ago

Hello everybody,
just joined the internals list (after being absent from php developers
lists for a while) so excuse my ignorance if any topic I bring up has
been discussed already. I checked the archives but couldn't find anything...

Proposal: Allow dangling commas in function call parameters.
Reasoning: We use some handy vararg tool functions and it's nice to be
able to write
foo(
1,
2,
3,
);
since it's then easy to add a new parameter without having to add a
comma to the previous list.

This would be symmetrical to the array() syntax. The patch for zend
(php4 from cvs) would be minimal and I can't see any
backwards-compatibility issues right now (patch attached).

Any opinions?

Regards,
- Chris

Andi Gutmans

22 years ago

At 11:32 PM 10/22/2003 +0200, Christian Schneider wrote:

>Hello everybody,
>just joined the internals list (after being absent from php developers
>lists for a while) so excuse my ignorance if any topic I bring up has been
>discussed already. I checked the archives but couldn't find anything...
>
>Proposal: Allow dangling commas in function call parameters.
>Reasoning: We use some handy vararg tool functions and it's nice to be
>able to write
>foo(
>         1,
>         2,
>         3,
>);
>since it's then easy to add a new parameter without having to add a comma
>to the previous list.
>
>This would be symmetrical to the array() syntax. The patch for zend (php4
>from cvs) would be minimal and I can't see any backwards-compatibility
>issues right now (patch attached).
>
>Any opinions?

The only reason array() supports this is because there are some cases where
people auto-generate initialization files which have a huge array()
construct and it makes it slightly easier (don't have the last element
problem).
In this case I don't see the same advantage and I see a disadvantage in
readability and the possibility for PHP to give such an empty argument a
meaning in future (although I doubt that'll happen).
So -1 from me.

Andi

Christian Schneider

22 years ago

Andi Gutmans wrote:

> In this case I don't see the same advantage and I see a disadvantage in
> readability and the possibility for PHP to give such an empty argument a
> meaning in future (although I doubt that'll happen).

Ok, here the real-world example from our HTML generation toolkit:
table(
tr(td('row 1 cell 1'), td('row 1 cell 2')),
tr(td('row 2 cell 1'), td('row 2 cell 2')),
);

Being able to easily append lines here would be really nice :-)
It doesn't break existing things _and_ it's up to the programmer to use
this feature, same as in array().

I was also thinking of proposing named parameters, i.e. basically
removing the need for array() in foo(array('style' => 'hot', 'size' =>
42)); but I guess that'll be even more controversial :-)

Ok, that's it from my side, it's up to you now,
- Chris

netcat

22 years ago

Christian Schneider wrote:

[snip]

>
> I was also thinking of proposing named parameters, i.e. basically
> removing the need for array() in foo(array('style' => 'hot', 'size' =>
> 42)); but I guess that'll be even more controversial :-)

Named parameters - i think is very good idea. I know i would use them.
I'm really not sure about the correct syntax for it though.
They should be optional and may have default values
and provide a way to extend old functions that
already have optional parameters.

Just for example:
function f($a,$b=false,keyword $c='xyz') {
}
f(1)
f(1,true)
f(1,c='www')
f(1,true,c='www')

Just general thoughts:
Maybe there should be a way to specify that
a keyword is required.
Maybe there should be a way to specify external
name other than argument variable name as in the
following example:

function g($a,keyword 'aa' $ab) {
}

>
>
> Ok, that's it from my side, it's up to you now,
> - Chris
>

--
NetCat



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Christian Schneider

22 years ago

netcat wrote:

> Named parameters - i think is very good idea. I know i would use them.
> I'm really not sure about the correct syntax for it though.

Important for our application would be that it works with varargs, as we
have a lot of (potential) parameters of which you normally only give a
small subset. And having a huge parameter list with default values just
doesn't do it there. We're using one associative array as parameter for
this purpose right now.

- Chris

Sebastian Bergmann

22 years ago

netcat wrote:

> Named parameters - i think is very good idea.

Named parameters are commonly implemented using an associated array in
PHP:

<?php
function foo($parameters) {}

foo(
array(
'foo' => 'bar',
'bar' => 'foo'
)
);
?>

--
Sebastian Bergmann
http://sebastian-bergmann.de/                   http://phpOpenTracker.de/

Das Buch zu PHP 5: http://professionelle-softwareentwicklung-mit-php5.de/