Let's say that initially, we have a complex data processing class designed to operate on an array of associative arrays, applying a transformation that converts all string values within the array to uppercase. Here's the initial version using PHP:
<?php
class DataProcessor
{
public function processData(array $items)
{
$processedItems = [];
foreach ($items as $item) {
$processedItem = [];
foreach ($item as $key => $value) {
if (is_string($value)) {
$processedItem[$key] = strtoupper($value);
} else {
$processedItem[$key] = $value;
}
}
$processedItems[] = $processedItem;
}
for ($i = 0; $i < min(3, count($processedItems)); $i++) {
echo "Processed Item: ";
print_r($processedItems[$i]);
}
}
}
We intend to expand this functionality, adding capabilities to filter the items based on a condition and allowing for custom transformations. The aim is to retain backward compatibility while introducing these enhancements. Here's the updated approach using optional parameters and closures:
<?php
class DataProcessor
{
public function processData(array $items, callable $condition = null, callable $transform = null)
{
if ($condition === null) {
$condition = function ($item) {
return true;
};
}
$processedItems = [];
foreach ($items as $item) {
if ($condition($item)) {
$processedItem = [];
if ($transform !== null) {
$processedItem = $transform($item);
} else {
// Default transformation: Convert string values to uppercase
foreach ($item as $key => $value) {
$processedItem[$key] = is_string($value) ? strtoupper($value) : $value;
}
}
$processedItems[] = $processedItem;
}
}
for ($i = 0; $i < min(3, count($processedItems)); $i++) {
echo "Processed Item: ";
print_r($processedItems[$i]);
}
}
}
// Usage examples:
$data = [
["name" => "apple", "quantity" => 10],
["name" => "orange", "quantity" => 5]
];
$processor = new DataProcessor();
// Default behavior - convert string values to uppercase
$processor->processData($data);
// Custom filter - select items with a quantity greater than 5
$processor->processData($data, function ($item) {
return $item['quantity'] > 5;
});
// Custom transformation - convert names to uppercase and multiply the quantity by 2
$processor->processData($data, null, function ($item) {
return [
'name' => strtoupper($item['name']),
'quantity' => $item['quantity'] * 2
];
});
In this evolved version, we've used optional parameters callable $condition and callable $transform for custom filtering and transformation of items. The default behavior processes all items, converting string values to uppercase, thus maintaining original functionality for existing code paths.
