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Rule ``explicit_string_variable``

doc/rules/string_notation/explicit_string_variable.rst

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================================= Rule explicit_string_variable

Converts implicit variables into explicit ones in double-quoted strings or heredoc syntax.

Description

The reasoning behind this rule is the following:

  • When there are two valid ways of doing the same thing, using both is confusing, there should be a coding standard to follow.
  • PHP manual marks "$var" syntax as implicit and "{$var}" syntax as explicit: explicit code should always be preferred.
  • Explicit syntax allows word concatenation inside strings, e.g. "{$var}IsAVar", implicit doesn't.
  • Explicit syntax is easier to detect for IDE/editors and therefore has colors/highlight with higher contrast, which is easier to read. Backtick operator is skipped because it is harder to handle; you can use backtick_to_shell_exec fixer to normalize backticks to strings.

Examples

Example #1


.. code-block:: diff

   --- Original
   +++ New
    <?php
   -$a = "My name is $name !";
   -$b = "I live in $state->country !";
   -$c = "I have $farm[0] chickens !";
   +$a = "My name is {$name} !";
   +$b = "I live in {$state->country} !";
   +$c = "I have {$farm[0]} chickens !";

Rule sets
---------

The rule is part of the following rule set:

- `@PhpCsFixer <./../../ruleSets/PhpCsFixer.rst>`_

References
----------

- Fixer class: `PhpCsFixer\\Fixer\\StringNotation\\ExplicitStringVariableFixer <./../../../src/Fixer/StringNotation/ExplicitStringVariableFixer.php>`_
- Test class: `PhpCsFixer\\Tests\\Fixer\\StringNotation\\ExplicitStringVariableFixerTest <./../../../tests/Fixer/StringNotation/ExplicitStringVariableFixerTest.php>`_

The test class defines officially supported behaviour. Each test case is a part of our backward compatibility promise.