DEV Community: Serhii Klochko

PHP 8.0, 8.1, 8.2, 8.3... what's new?! CheatSheet.

Serhii Klochko — Thu, 18 Apr 2024 19:49:32 +0000

The idea of this note is to write down PHP 8+ what's news briefly, so they are visible all at once on a single page. Like a cheat-sheet.

Keep in mind that these are just the basic features, see each version's link for more details.

PHP 8.0 What's new

Named function arguments (i.e. arg_name: value, instead of filling preceding default arguments)
Attributes (instead of DocBlock comments)
Constructor property promotion (properties in constructor instead of normal declaration)
Union types (i.e. int|string $varname)
Match expression (to replace some of switch-case)
Nullsafe operator (instead of nesteds ifs)
Saner string to number comparisons (i.e. 0 == 'somestrval' // not true anymore)
Consistent type errors for internal functions (internal functions throws typed exceptions now)
Just-In-Time compilation (2x performance in some specific long-running applications)
and more

PHP 8.1 What's new

Enumerations (enums)
Readonly Properties (for VO and DTO)
First-class Callable Syntax (to get a reference to any function, i.e. $fn = strlen(...);)
New in initializers (for nested attributes)
Pure Intersection Types (Iterator&Countable $value but not A&B|C)
Never return type (to be clear that function returns nothing)
Final class constants (cannot override functions and inherit classes)
Explicit Octal numeral notation // TODO: add some description below
Fibers
Array unpacking support for string-keyed arrays
and more

PHP 8.2 What's new

Readonly classes
Disjunctive Normal Form (DNF) Types
Allow null, false, and true as stand-alone types
New "Random" extension
Constants in traits
Deprecate dynamic properties
and more

PHP 8.3. What's new

Typed class constants
Dynamic class constant fetch
New #[\Override] attribute
Deep-cloning of readonly properties
New json_validate() function
New Randomizer::getBytesFromString() method
New Randomizer::getFloat() and Randomizer::nextFloat() methods
Command line linter supports multiple files
and more

How to flatten a PHP array

Serhii Klochko — Thu, 15 Feb 2024 01:13:02 +0000

Here is what I was looking for:

function true_flatten(array $array, array $parents = [])
{
    $return = [];
    foreach ($array as $k => $value) {
        $p = empty($parents) ? [$k] : [...$parents, $k];
        if (is_array($value)) {
            $return = [...$return, ...true_flatten($value, $p)];
        } else {
            $return[implode('_', $p)] = $value;
        }
    }

    return $return;
}

Sample array:

$r = [
    'a' => 'value1',
    'b' => [
        'c' => 'value1.1',
        'd' => 'value1.2',
    ],
    'e' => 'value2',
    'f' => [
        'j' => [
            'k' => 'value2.1',
            'm' => 'value2.2',
            'n' => 'value2.3',
        ],
    ],
    'o' => 'value3',
    'p' => [
        'some' => [
            'very' => [
                'deep' => [
                    'item' => [
                        'first',
                        'second',
                    ]
                ]
            ]
        ]
    ],
    'q' => 'value5',
]; // sample data

Output:

{
    "a": "value1",
    "b_c": "value1.1",
    "b_d": "value1.2",
    "e": "value2",
    "f_j_k": "value2.1",
    "f_j_m": "value2.2",
    "f_j_n": "value2.3",
    "o": "value3",
    "p_some_very_deep_item_0": "first",
    "p_some_very_deep_item_1": "second",
    "q": "value5"
}

How to check directory size in Linux/Ubuntu via command line

Serhii Klochko — Thu, 25 Jan 2024 14:19:26 +0000

(Note: It works for MacOS too)

If you need to check the size of a directory on your computer, it is better to use special tools such as ncdu, dust or tree. I prefer ncdu - it does the job!

But, it is more common to use CLI if you work with a remote machine, often without a permission to install additional software into it. Then pre-installed tools come to rescue - du. See how I use it below.

du -h .

This gives us a list of all directories and subdirectories in current directory. That's not what we meant, huh?
Note: The dot character can be replaced with a relative or absolute directory path.

du -sh .

The option -s stands for summary result. Now we see the entire folder size. But still, how to see each subfolder individually?

du -sh ./*

# or just:
du -sh *

Here it is! Now we see the size of each subfolder of 1st level.

du -sh .[^.]* *

Then you might want to see hidden folder and files too. A bit more complicated with regular expression.

Moreover, usually we would like to see result sorted, the largest elements come first:

du -sh * | sort -rh

The sort options -r is for reverse, and -h is for natural/numeric sort order.

These are just the basics, please share your favourite method in the comments.