Refactoring to Collections

A presentation inspired by Adam Wathan's book "Refactoring to Collections". Presented June 2nd, 2016 @ the Laravel Austin (@LaravelAustin)

Transcript

1. REFACTORING TO
   COLLECTIONS
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2. HIGHER ORDER FUNCTIONS
   A function that takes another function as a parameter, returns a
   function, or does both.
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3. "Higher order functions are powerful because they let us create
   abstractions around common programming patterns"
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4. FUNCTIONAL BUILDING BLOCKS
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5. EACH
   No more than a foreach loop wrapped inside of a higher order
   function.
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6. function each($items, $func)
   {
   foreach ($items as $item) {
   $func($item);
   }
   }
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7. Imagine a world without a foreach loop
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8. function each($items, $func)
   {
   for ($i = 0; $i < count($items); $i++) {
   $func($items[$i]);
   }
   }
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9. MAP
   Used to transform each item in an array into something else, creating a
   new array in the process.
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10. function map($items, $func)
    {
    $result = [];
    foreach ($items as $item) {
    $result[] = $func($item);
    }
    return $result;
    }
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11. FILTER
    Used to filter out any elements of an array that you don't want.
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12. function filter($items, $func)
    {
    $result = [];
    foreach ($items as $item) {
    if ($func($item)) {
    $result[] = $func($item);
    }
    }
    return $result;
    }
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13. REJECT
    A close cousin of filter, that simply flips the conditional to be more
    expressive.
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14. REDUCE
    Used to take some array of items and reduce it down to a single value.
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15. function reduce($items, $callback, $initial)
    {
    $accumulator = $initial;
    foreach ($items as $item) {
    $accumulator = $callback($accumulator, $item);
    }
    return $accumulator;
    }
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16. Speaking of patterns....
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17. function map($items, $func)
    {
    return reduce($items, function ($mapped, $item) use ($func) {
    $mapped[] = $func($item);
    return $mapped;
    });
    }
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18. THINKING IN STEPS
    Break a problem into many steps. Turn "I can't because..." into "I could
    if..."
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19. THE PROBLEM WITH PRIMITIVES
    We have to operate on them from the outside by passing them as
    parameters into other functions.
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20. $camelString = lcfirst(
    str_replace(' ', '',
    ucwords(str_replace('_', ' ', $snakeString))
    )
    );
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21. $camelString = $snakeString->replace('_', ' ')
    ->ucwords()
    ->replace(' ', '')
    ->lcfirst();
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22. PRACTICE
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