doc/todo/be_more_selective_about_running_hooks.mdwn

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+[[!template  id=gitbranch branch=chrismgray/exclusive-hooks author="[[chrismgray]]"]]
+
+Sometimes plugins register a function with `hook`, but they only want
+the function called with the content that they know how to deal with.
+Normally, this means that they call `pagetype` first thing in the
+function, determine if they know how to deal with the content, and
+only do anything if they do.  
+
+This is a bit wasteful in itself, but for external plugins, it's
+really bad.  For functions like `scan` and `linkify`, where the entire
+page is sent back and forth over `stdout` and `stdin`, it really slows
+things down.  
+
+Thus, I propose that there be a new optional parameter to `hook` that
+tells it that the function should only be called for files whose type
+is the same as the id of the plugin calling `hook`.  I have called
+this parameter `exclusive` in my branch, but this might not be the
+best name.
+
+[[!tag patch]]