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What is basic concept behind hooks?
How does comment_field_extra_fields() implement hook_field_extra_fields()? How is a hook implemented by another function? Does it extend another class to use a hook function?
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marked as duplicate by kiamlaluno♦ Aug 24 '12 at 22:58
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module_implements()andmodule_invoke()in the API, and this excellent resouce – Clive♦ Aug 24 '12 at 20:56