PHP Standards Recommendations - PHP-FIG

PHP Standards
Recommendations
(PSR)
Akshay Khale

(Sr. Software Engineer)

– Martin Fowler
“Any fool can write code that a computer can
understand. Good programmers write code that
humans can understand.”

PSR-1: Basic Coding
Standards.
• MUST use only <?php and <?= tags.

• MUST use only UTF-8 Encoding.

• SHOULD either declare symbols or cause side-eﬀects.

• Class names MUST be declared in CamelCase or
StudlyCaps.

• constants MUST be declared in all UPPER_SNAKE_CASE.

• Method names MUST be declared in camelCase.

Quiz Time: What is wrong with
following code snippets?

PSR-2: Coding Style Guide
• 4 Space indenting (No Tabs).

• Soft Line limit 120 Characters.

• Blank space after namespace declaration before use.

• Closing Brace “}” always on a separate line.

• Opening Brace “{” Same line (with a space before) for control statements
and next line for Classes and functions.

• Space before open parentheses “(” for control statements and not for
functions.

• Visibility mode is must for all properties and methods. abstract and ﬁnal
before visibility and static after the visibility.

PSR-3: Logger Interface
• Only allowed Log levels: debug, info, notice, warning, error,
critical, alert, emergency.

• MUST implement PsrLogLoggerInterface.

• MUST throw PsrLogInvalidArgumentException exception
on invalid log level.

• public function log($level, $message, array $context =
array());
• One can consider extending PsrLogAbstractLogger class
which implements LoggerInterface.

Sample Logger Class:
https://github.com/akshaykhale1992/luxio-logger

PSR-4: Autoloader
• Namespace: <vendor_namespace>/
<package_namespace>[/<subnamespace>/]/
<class_name>.

• Folder structure should also follow the namespace
pattern.

PSR-6: Caching Interface
• MUST implement PsrCacheCacheItemPoolInterface and
PsrCacheCacheItemInterface.

• Concepts: Pool, Items, Key, Data, TTL, Hit, Miss.

• Should not throw any Exception.

PSR-7: HTTP message
interfaces
• Request Structure

• Response Structure

• Interfaces: PsrHttpMessageRequestInterface and
PsrHttpMessageResponseInterface.

PSR-11: Container interface
• MUST implement PsrContainerContainerInterface.

• MUST throw PsrContainerNotFoundExceptionInterface
exception if object not found.

• Directly thrown exceptions must implement
PsrContainerContainerExceptionInterface interface.

Standards that most of the
developers follow.
• If a file defines a Class then it should not have any other declarations though PSR
allows.

• Files with functions should have only function definitions.

• Files with class / functions definitions should not have a closing PHP Tag (?>) and
should have an empty line before EOF.

• Helper files must have function_exists check.

• Code MUST be correctly formatted based on the PSR rules. (editor plugins can be used
for the same).

• Arrays properties should be on separate lines.

• All declarations MUST have dock-blocks.

• Branch names MUST follow bitbucket Branching Model.

Cont.
• Use static instead of self for calling static class members.

• Use die instead of exit.

• Make use of destructors for unsetting objects and/or closing opened files.

• There should not be any commented code or commented die / dd statements.

• SHOULD avoid else block in case of if statements.

• Recommended to make use of exceptions in-case of invalid details which should be
handles at calling end.

• Try to use User defined constants instead of System constants. A constants class should
be created for defining all the constants that are being used in the project. E.g. instead of
using “/” for directory paths use DIRECTORY_SEPARATOR or instead of using supplier_id
== 7 check use supplier_id == Constants::DELHIVERY_SUPPLIER_ID.

• PHP Unit Test cases are compulsory.

PHP Standards Recommendations - PHP-FIG

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