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CAST IN THE NAME OF PHP, YE NOT GUILTY

Minimum PHP version: 7.0.0 Packagist Github Actions Coverage Status Psalm coverage

ABOUT

  • You can cast any values in the weak mode manner, even if you are in the strict mode (strict_types=1).

INSTALL

composer require sj-i/php-cast

SUPPORTED VERSIONS

  • PHP 7.0+

USAGE

use PhpCast\Cast;
use PhpCast\NullableCast;

// int(1)
$int_value = Cast::toInt('1');
// string(1) "1"
$string_value = Cast::toString(1);
// float(1)
$float_value = Cast::toFloat(1);
// bool(true)
$bool_value = Cast::toBool(1);

// TypeError
$int_value = Cast::toInt('a');
// TypeError
$int_value = Cast::toInt(null);


// int(1)
$int_value = NullableCast::toInt('1');
// string(1) "1"
$string_value = NullableCast::toString(1);
// float(1)
$float_value = NullableCast::toFloat(1);
// bool(true)
$bool_value = NullableCast::toBool(1);

// TypeError
$null_value = NullableCast::toInt('');
// null
$null_value = NullableCast::toInt(null);

HOW IT WORKS

  • Return type declarations in weak mode files do the job.
  • PhpCast\Cast is defined in a file declared as strict_types=0
    • Though strict_types=0 is the current default of PHP, it is explicitly declared to assert the intent.
  • The type checks for parameters are done in the caller mode, but the type checks for return values are always done in the callee mode.

"WHY WEAK MODE? I WANT TO USE STRICT MODE IN EVERYWHERE!"

  • To use strict_types=1 without any strict_types=0 codes, explicit casts have to be used for untyped data from external sources like DB or HTTP requests.
  • But in PHP, explicit cast like (int)$foo never fails with a few exceptions.
    • (int)'abc' silently results to 0 and doesn't emit a warning.
  • So some validations are necessary before just using casts.
  • If explicit casts are used without proper validations by a lazy programmer, the purpose of the type declarations are totally ruined.
    • This was, if I understand it correctly, one of the reasons that strict type checks weren't totally welcomed with open arms during the discussion introducing the scalar type hinting to PHP.
  • Defining proper rules of validations and type conversions is sometimes overkill.
    • Even though defining them are always "correct" things to do, in humans life, there are times you don't need to be so correct.
  • Let's cast untyped values in the weak mode manner, use the "official" rules of validations and type conversions in the PHP world!
    • No need to invent and learn new rules every day every night everywhere.
    • If the "official" rules doesn't fit your needs, then define and use your own rules selectively there.
  • If you've ever read the accepted RFC of STH, you would notice the use of weak mode like this library has been already mentioned there.

    This proposal is not a compromise. It is an attempt of allowing strict typing to work in PHP. A mechanism to bridge untyped PHP code with strict typed PHP code, a “weak” bridge, would be required (otherwise explicit (type) casts would be needed). This proposal unifies the strict and weak typing into a single system that integrates tightly and behaves consistently.

LICENSE

MIT