Introducing CTOR: Prefer Constructor over Always-Called Setters

2026-05-27

When you build a house, you don't pour the foundation first and then hope someone remembers to add the load-bearing walls a week later. You build the structure that has to be there at the start.

Yet in PHP, we sometimes do the opposite:

$tomasHuman = new Human();
$tomasHuman->setName('Tomas');
$tomasHuman->setAge(36);
$tomasHuman->setEmail('tomas@example.com');

Three lines, and only the first one is required. The other two? A polite suggestion. Forget one of those setters, and $tomasHuman quietly walks around half-built until something explodes deep inside project three layers down.

I've been bumping into this pattern on legacy codebases for years. Most of the time, those setters are not optional - they're always called right after new (in different order or much later though).

They pretend to be flexible, but in practice they are required dependencies.

So I made a small PHPStan extension to find them.

What does the package do?

Ctor adds a PHPStan rule that looks for this exact shape, repeated all over the codebase:

$tomasHuman = new Human();
$tomasHuman->setName('Tomas');
$tomasHuman->setAge(36);
$tomasHuman->setEmail('tomas@example.com');

// another file
$johnHuman = new Human();
$johnHuman->setName('John');
$johnHuman->setAge(23);
$johnHuman->setEmail('john@example.com');

...and suggests turning it into this:

$tomasHuman = new Human('Tomas', 35, 'tomas@example.com');

$johnHuman = new Human('John', 23, 'john@example.com');

That's it. A clear nudge from PHPStan:

• "hey, these setters look suspiciously mandatory - have you considered the constructor?"

Why Constructor over Setters?

Chained setters after new are often implicit required dependencies in disguise.

• The object is never used between new and the last setter call - it's not really "configurable", it's "incomplete"
• Forget a single setter, and the object goes into the world in a half-valid state
• IDE and PHPStan can't tell you which setters are required, because the constructor signature says "I need nothing"

Move it all to the constructor and every one of these problems disappears. The object becomes valid from the moment it exists - which is the whole point of having a constructor in the first place.

2 steps to install

1. Require it via composer:

composer require tomasvotruba/ctor --dev

2. If you use phpstan/extension-installer, you're done - the rule is loaded automatically.

Now run PHPStan and see how many "constructors-in-hiding" your codebase has:

vendor/bin/phpstan

The repository is here: TomasVotruba/ctor

If you spot a false positive, a missed case, or a related smell you'd like the rule to catch - open an issue, I'd love to hear it.

Happy coding!