roave/no-floaters

PHPStan Rules to Disallow Float proliferation in contexts where IEEE-754 rounding errors are not acceptable

1.3.0 2020-01-28 16:45 UTC

This package is auto-updated.

Last update: 2020-01-28 16:51:46 UTC


README

roave/no-floaters

Build Status Latest Stable Version

This library is a PHPStan plugin that disallows:

  • declaration of float properties
  • float method parameters
  • float method return types
  • assignment of float values to variables or properties

The reason for this restriction is that rounding errors coming from floating point arithmetic operations are not acceptable in certain business logic scenario, such as dealing with money, evaluating exam results, rocket science, etc.

An example of such problems can be seen with the following typical example:

var_dump((0.7 + 0.1) === 0.8); // output: bool(false)

This can mean no trouble at all, or a lot of trouble, depending on how many numbers you are running through your system, so it is advisable to avoid float for domains where rounding can potentially lead to trouble.

float is still perfectly acceptable in many programming contexts, and this ruleset should only be applied where it is critical not to introduce rounding errors.

Installation

composer require --dev roave/no-floaters

Configuration

In your phpstan.neon configuration, add following section:

includes:
	- vendor/roave/no-floaters/rules.neon

Optionally, you can configure the library to disallow any float-producing expression at all, by adding following to your phpstan.neon:

parameters:
	disallowFloatsEverywhere: true

If the above is enabled, given the following example-file.php contents:

<?php

$a = 1 / 3;

You should get something like following:

vendor/bin/phpstan analyse example-file.php -l 7
 1/1 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100%

 ------ -----------------------------------------------------
  Line   example-file.php
 ------ -----------------------------------------------------
  3      Cannot assign float to $a - floats are not allowed.
 ------ -----------------------------------------------------


 [ERROR] Found 1 error

roave/no-floaters for enterprise

Available as part of the Tidelift Subscription.

The maintainers of roave/no-floaters and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. Learn more..

If you need help with setting up this library in your project, you can contact us at team@roave.com for consulting/support.