PHP passing array to function

Question

I've seen a few people ask a similar question. But I do need a little more clarification on this particular subject.

I have several functions that pass several arguments. I even have a few that are about 10 arguments. (didn't initially plan it, simply grew over time)

I don't have any problems looking at my source code to find out what the 7th argument is, but it does get tedious. Most of the time I know what arguments to pass, just not the position.

I had a few ideas to simplify the process for me.

a) pass 1 argument, but divide everything with some delimiter. (but that's a bad idea!, since I still need to remember the position of each.

function myfunc('data|data|data|'){
          // explode the string
}

b) pass an array with key and values, and look for the key names inside my function, and act accordingly.

function myfunc(array('arg1' => 'blah blah', 'arg2' => 'more blah')){
  // loop through the array
}

c) keep it as it is.

function myfunc($arg1,$arg2,$arg3,$arg4,$arg5........){
// yay

}

So, I'm seeking other options and better ideas for handling functions with growing argument lists.

what are these functions and what are these arguments? most likely it's a consequence of poor design and number of parameters can be considerable reduced. — Your Common Sense
– Your Common Sense, Commented Sep 26, 2011 at 18:13
While in it's current edition the question is absolutely pointless and subjective. — Your Common Sense
– Your Common Sense, Commented Sep 26, 2011 at 18:14
Why not refactor your code and split your function into several others? Why not use objects and pass them along to other objects? Having about 10 arguments should raise a red flag of bad design. — kgilden
– kgilden, Commented Sep 26, 2011 at 18:14

Joseph Silber · Accepted Answer · 2011-09-26 18:23:39Z

8

In my opinion, the best way to it is by passing in an associative array. That way you immediately see what each argument does. Just be sure to name them descriptively, not arg1 & arg2.

Another advantage an associative array, is that you don't have to care about the order in which the arguments are being passed in.

Just remember that if you use an associative array, you lose PHP's native way of assigning default values, e.g.:

function doSomething($arg1 = TRUE, $arg2 = 55) { }

So, what you have to do is create your own set of default options, and then merge your arrays:

function doSomething( $props = array() )
{
    $props = array_merge(array(
        'arg1' => TRUE,
        'arg2' => 55
    ), $props);

    // Now use the $props array
}

edited Sep 26, 2011 at 18:23

answered Sep 26, 2011 at 18:11

Joseph Silber

221k59 gold badges369 silver badges292 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

klaustopher Over a year ago

In the head of the foreach it should be $props and not $options

zzzzBov Over a year ago

+1 for passing associative array; -1 for trying to reinvent the wheel.

Joseph Silber Over a year ago

@zzzzBov - In most situations you wouldn't want array_merge_recursive. However, array_merge does the trick (as does +=), and I've updated my answer.

zzzzBov Over a year ago

@Joseph Silber, can you give an example where you wouldn't want array_merge_recursive?

Joseph Silber Over a year ago

@zzzzBov - Maybe I'm missing something, but I think that array_merge_recursive defeats the purpose. Check out my examples of array_merge_recursive and array_merge, and tell me yourself which one makes more sense.

|

phihag · Accepted Answer · 2011-09-26 18:11:32Z

2

b) (an associative array) is by far the easiest, most adaptible (as it allows simulating default keyword arguments), and least error-prone variant.

answered Sep 26, 2011 at 18:11

phihag

289k75 gold badges475 silver badges489 bronze badges

1 Comment

coffeemonitor Over a year ago

true, it seems most adaptable, and I can see see exactly what my keywords are, leaving less guesswork. I put it to the test, and so far it's been good to me.

zzzzBov · Accepted Answer · 2011-09-26 18:11:26Z

2

go with the myfunc($options) form when you have many optional parameters that can be mixed and matched. Use array_merge_recursive with a default options array, and you'll be golden.

answered Sep 26, 2011 at 18:11

zzzzBov

180k57 gold badges328 silver badges375 bronze badges

Comments

Maxim Krizhanovsky · Accepted Answer · 2011-09-26 20:42:49Z

1

First, see if you can introduce paramter object. It not necesseary to replace all 7 parameters, but maybe you can lower their count.

Next, examine the function itself - why it needs so many parameters, maybe it just does to much things? Is Replace parameter with method / Replace parameter with explicit method applicable?

By the way, Refactoring is great reading!

edited Sep 26, 2011 at 20:42

answered Sep 26, 2011 at 18:17

Maxim Krizhanovsky

26.8k5 gold badges62 silver badges91 bronze badges

Comments

smp7d · Accepted Answer · 2011-09-26 18:12:09Z

0

Depending on the intention of the function, sometimes it is appropriate to pass an object.

answered Sep 26, 2011 at 18:12

smp7d

5,0422 gold badges28 silver badges49 bronze badges

Comments

klaustopher · Accepted Answer · 2011-09-26 18:15:04Z

Let's not talk about solution #1. You already say that it is bad...

I like the second idea of passing in this hash/associative array. It feels rubylike :) The thing you are doing is that you are giving up some checks that you would get for free. If you call a function and forget an argument the runtime complains and the script stops executing. In your scenario you would have to do all those checks inside your function: Are all necessary options given? Are the values the right types, etc?

I would say, the decision is up to your taste if it's just you working on the code. If others are working with you, I would ask them about their opinion. Until then, I would stick with the classic approach of having the function with 7 arguments

hakre · Accepted Answer · 2011-09-26 18:17:14Z

0

Associative array with keys as parameter names, order does not count (do not to forget you document which keys are expected):

function myFunc(array $args)
{
    # default values
    $args += array('arg1' => 'default1', 'arg2' => 'default2');
}

Sometimes you want to verify that you drop all unimportant keys from the input as well. A useful function for this is array_intersect_key^Docs.

answered Sep 26, 2011 at 18:17

hakre

200k55 gold badges453 silver badges865 bronze badges

Comments

webbiedave · Accepted Answer · 2011-09-26 18:31:40Z

0

function myfunc($arg1,$arg2,$arg3,$arg4,$arg5........){

With the limited information provided, I would have to say keep it as is. The reason for this is that your function signature shows that none of your arguments have default values (they are all required).

If you make it an associative array, then you remove the parser's ability to warn about ill-called functions, i.e.:

Missing argument 2 for some_function, called in [etc.]

IDEs can help with function calling assistance if you have difficulty remembering all the arguments.

Basically, if it's a required argument, it should be in the function signature.

answered Sep 26, 2011 at 18:31

webbiedave

49k8 gold badges92 silver badges104 bronze badges

Collectives™ on Stack Overflow

PHP passing array to function

8 Answers 8

6 Comments

1 Comment

Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

8 Answers 8

6 Comments

1 Comment

Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related