How to Write Consistent PHP Code - PHPR package blog

Introduction

Examples of Consistency Manipulating Collections

Conclusion

Introduction

Have you ever forgot what are the parameters of a PHP class method? Or if it returns 0, true or false? The first question can be solved using IDEs, for that that like to use IDEs. I just use, and love to use, Vim with a lot of plugins. So, for me, it's not an option.

The latter question can lead to confusing behavior, because it can mess things up on some levels. We need to check, as with the first question, the documentation and perhaps the method return value, comparing it with some ways that can not be very productive.

I use to code a lot using Ruby, where we can say that most part of time it follows the principle of least surprise. You don't need to think or have any surprises with unexpected behavior of the code. And it also has a strong object oriented and functional mood with all its objects and methods, blocks, closures, whatever.

So, I'm trying to copy some Ruby features, starting with arrays (collections), to try to make some things easier in PHP. That's why I wrote the PHPR package. You can check it here. There is more detailed documentation on its wiki.

Solid as a rock!

Examples of Consistency Manipulating Collections

Let's see some examples. First, create the object, passing an array (associative or not):

$t = new PHPR\Collection([0 => "zero", 1 => "one", 2 => "two"]);

Don't you just hate the "undefined index" error messages? Now is not a problem anymore,
it just returns null when the index is not found:

echo $t[10]."\n"; // => null

Of course, the array style accessor works as expected:

echo $t[1]."\n"; // => "one"

Finding collection elements that meet certain conditions is very easy:

$col = new PHPR\Collection(["one", "two", "three"]);
$rst = $col->select(function($e) {
    return strlen($e) > 3;
});
var_dump($rst->values());

Outputs:

array(1) {
  [0] =>
  string(5) "three"
}

Transforming the collection elements:

$col = new PHPR\Collection(["one", "two", "three"]);
$rst = $col->map(function($e) {
    return strrev($e);
});
var_dump($rst->values());

Outputs:

array(3) {
  [0] =>
  string(3) "eno"
  [1] =>
  string(3) "owt"
  [2] =>
  string(5) "eerht"
}

Splitting the collection in two collections, one that meets certain conditions and another that doesn't, is done using partition:

$col  = new PHPR\Collection([1, 2, 3, 4, 5]);
$cols = $col->partition(function($e) {
    return $e % 2 == 0;
});

echo "even numbers:\n";
var_dump($cols[0]->values());

echo "odd numbers:\n";
var_dump($cols[1]->values());

Outputs:

even numbers:
array(2) {
  [0] =>
  int(2)
  [1] =>
  int(4)
}
odd numbers:
array(3) {
  [0] =>
  int(1)
  [1] =>
  int(3)
  [2] =>
  int(5)
}

Reduce the elements to a single result is done using inject:

$col = new PHPR\Collection([1, 2, 3, 4, 5]);
echo "sum is ".$col->inject(function($memo, $value) { return $memo + $value; })."\n";
echo "sum is ".$col->inject(function($memo, $value) { return $memo + $value; }, 10)."\n";

Outputs:

sum is 15
sum is 25

Grouping the collection elements:

$col = new PHPR\Collection(["one", "two", "three"]);
var_dump($col->groupBy(function($e) { 
   return strlen($e); 
}));

Output:

array(2) {
    [3] =>
    array(2) {
      [0] =>
      string(3) "one"
      [1] =>
      string(3) "two"
    }
    [5] =>
    array(1) {
      [0] =>
      string(5) "three"
    }
}

We can even chain the methods:

$changed = self::$_col->map(function($e) {
   return strrev($e);
})->select(function($e) { return strlen($e) <= 3; });
var_dump($changed->values());

Output:

array(2) {
   [0] =>
   string(3) "eno"
   [1] =>
   string(3) "owt"
}

A lot of other examples can be found on the wiki.

Conclusion

A lot of work still needs to be done, including other objects (strings, etc), but the goal to deal with objects using it's methods without need to remember what is the order the parameters and having more consistency on the way we expect the return values are being accomplished, IMHO.

Contributions with Ideas and code are welcome, of course. If you liked this article or you would like to ask a question about achieving PHP code consistency, post a comment here.

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How to Write Consistent PHP Code - PHPR package blog

Contents

Introduction

Examples of Consistency Manipulating Collections

Conclusion

Introduction

Examples of Consistency Manipulating Collections

Conclusion

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