Modern programming languages like C# and Java 1.5 Tiger introduced us new very convenient feature called annotations.
Though it’s rather a new innovation, many Java users are using it for a long time already (for auto-generating source code, configuration files for different frameworks e.t.c). Here I mean rather the ideology then the implementation. Take a look at xDoclet.
This library provides you with similar features like xDoclet does - all annotations are stored in PHPDoc tags and accessible in runtime.
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