danog/psalm
1
0
Fork 0
mirror of https://github.com/danog/psalm.git synced 2024-11-26 20:34:47 +01:00
Code Issues Projects Releases Wiki Activity
be87bb7300
psalm/docs
History
lhchavez be87bb7300
Support intersection types for object-like arrays (#3064) 
This change allows expressing the intersection of multiple object-like
arrays. The resulting type will contain the (merged via intersection)
properties of all the object-like arrays involved in the intersection.

This should allow to express the resulting type of an `array_merge()`
operation, which is tricky to do in the context of a templated type.
2020-04-08 09:35:53 -04:00
..
annotating_code Support intersection types for object-like arrays (#3064) 2020-04-08 09:35:53 -04:00
manipulating_code Add opening <?php tags to all PHP snippets 2020-03-21 09:24:41 -04:00
running_psalm remove dead link 2020-04-05 17:24:05 -04:00
how_psalm_works.md Add opening <?php tags to all PHP snippets 2020-03-21 09:24:41 -04:00
README.md Add opening <?php tags to all PHP snippets 2020-03-21 09:24:41 -04:00
what_makes_psalm_complicated.md stripping trailing whitespace 2019-02-11 18:39:19 -05:00

README.md

About Psalm

Psalm is a static analysis tool that attempts to dig into your program and find as many type-related bugs as possible.

It has a few features that go further than other similar tools:

  • Mixed type warnings
    If Psalm cannot infer a type for an expression then it uses a mixed placeholder type. mixed types can sometimes mask bugs, so keeping track of them helps you avoid a number of common pitfalls.

  • Intelligent logic checks
    Psalm keeps track of logical assertions made about your code, so if ($a && $a) {} and if ($a && !$a) {} are both treated as issues. Psalm also keeps track of logical assertions made in prior code paths, preventing issues like if ($a) {} elseif ($a) {}.

  • Property initialisation checks
    Psalm checks that all properties of a given object have values after the constructor is called.

Psalm also has a few features to make it perform as well as possible on large codebases:

  • Multi-threaded mode
    Whereever possible Psalm will run its analysis in parallel to save time. Useful for large codebases, it has a massive impact on performance.

  • Incremental checks
    When using the --diff command line option, Psalm will only analyse files that have changed and files that reference them.

Example output

Given a file implode_strings.php:

<?php
$a = ['foo', 'bar'];
echo implode($a, ' ');

> ./vendor/bin/psalm implode_strings.php
ERROR: InvalidArgument - somefile.php:3:14 - Argument 1 of implode expects `string`, `array` provided (see https://psalm.dev/004)

Inspirations

There are two main inspirations for Psalm:

  • Etsy's Phan, which uses nikic's php-ast extension to create an abstract syntax tree
  • Facebook's Hack, a PHP-like language that supports many advanced typing features natively, so docblocks aren't necessary.

Index