PHP 7.3 Changes

PHP 7.3 is a smaller application-facing release. Flexible heredoc syntax, trailing commas in function calls, array_key_first(), array_key_last(), and is_countable() are useful maintenance improvements.

Changes Worth Recognising

• Use array_key_first() and array_key_last() instead of moving an array pointer for simple key lookup.
• is_countable() helps when maintaining mixed legacy inputs.
• Trailing commas reduce diff noise in multiline calls.
• Flexible heredoc indentation makes embedded text easier to align.

Representative Code

<?php

$totals = ['draft' => 4, 'published' => 12];

echo array_key_first($totals) . PHP_EOL;
echo array_key_last($totals) . PHP_EOL;

// Prints:
// draft
// published

Upgrade Review

• Do not confuse first or last insertion order with minimum or maximum value.
• Use a clear domain type instead of is_countable() when you control the API.
• Run formatting tools after adopting multiline trailing commas.

These additions are small, but they replace several awkward patterns that often survive in long-lived codebases.