PHPDeps is a simple tool to detect circular dependencies in your modules, whatever you consider as a module or package.

Module is an organized unit of code, which is supposed to be treated as single entity. By grouping classes and functions into modules we can reason about the design at a higher level of abstraction.

PHPDeps is available via composer:

Please, note that PHPDeps is used during the development. It’s not a part of your application, hence --dev.

This is a general programming problem. If this subject is new to you, or you just need a refresher here are some quick references:

1. Why Cyclic Dependencies are Bad

2. What is circular dependency and why is it bad?

3. Circular dependency

4. Acyclic dependencies principle

5. The Principles of OOD (The Acyclic Dependencies Principle part; in the end, most of the writers refer to this piece of literature)

PHPDeps detects module usage by reading use section of your PHP files. This means that PHPDeps requires namespaces to be present.

PHPDeps assumes that all classes and functions belonging to a single module have the same namespace prefix in their fully qualified name.

For example, if we tell PHPDeps that SomeModule has namespace of ACME\Lib\Modules\SomeModule and PHPDeps analyzes a following file which belongs to OtherModule:

Then PHPDeps notices that OtherModule depends on SomeModule.

Once all modules are analyzed, PHPDeps creates a dependency graph and looks for any cycles in it.

If you are all configured and set then just execute:

If your configuration file is not named phpdeps.xml then you can pass it as --config option:

It’s suggested to add phpdeps call to scripts section in your composer.json:

You can also run it alongside your tests:

Let’s consider a simplified structure of PHPDeps itself:

First, you need to prepare a configuration file that will allow PHPDeps to find your modules:

1. First option is to directly define your modules.

2. Each module needs a name, but currently this is only used for displaying purposes.

3. Each module also needs a namespace prefix, this is used to check whether any other module depends on it. If module is a file then this needs to be fully qualified name of that module.

4. Module path allows PHPDeps to find and analyze your module, this can be either filepath or dirpath.

5. Second option is to define a module detector, right now PHPDeps supports detection of only dir based modules.

6. Namespace prefix, directory name of found modules are appended to this to create actual module namespaces.

7. Directory where modules are to be searched for.

Once you have a configuration ready, you can execute:

If everything is all right you get nice OK message:

If something is amiss, you get:

Please, note that this example was generated by adding just one dependency to Commands module in Modules module.

At the moment PHPDeps does not provide any additional help in resolving the circular dependencies problem.

Configuration is a simple XML file. Provided XSD allows for code completion and easy validation. Currently, configuration uses simple format consisting of only XML tags and no attributes

• <PHPDeps> - Configuration root element.

  • <Modules> - Grouping tag for all kinds of module definitions.

    • <Module> - Defines and describes a single module.

      • <Name> - Module name, used for display purposes.

      • <Namespace> - Namespace prefix, to check whether any other module depends on it. If module is a file then this needs to be fully qualified name of that module.

      • <Path> - Module path allows PHPDeps to find and analyze your module, this can be either filepath or dirpath.

  • <Detectors> - Grouping tag for all kinds of detector definitions.

    • <ModuleDetector> - Defines and describes a single basic module detector.

      • <Namespace> - Namespace prefix, directory name of found modules are appended to this to create actual module namespaces.

      • <Path> - Directory where modules are to be searched for.

Please, refer to built-in help command.