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Changes between Version 3 and Version 4 of Ticket #17019, comment 18

v3	v4
15	15	causes my_function to be executed every time WP_Query applies filters for any query; I have no choice.
16	16
17		Same for my_function2 and my_function3 which also want to filter posts_where, but for a different use case. All 3 of them, when hooked directly to posts_where, will each be executed every N times posts_where filters are applied. Is there not some overhead in needless call_user_func_array() calls?
	17	Same for my_function2 and my_function3 which also want to filter posts_where within the same http request, but for different queries. Each one, when hooked directly to posts_where, will each be executed every N times posts_where filters are applied. Is there not some overhead in needless call_user_func_array() calls?
18	18
19	19	So as it stands, my plugin code will instead hook '''one''' function to posts_where and let it route the traffic. But most plugin / theme authors won't bother to do that, so I thought it would be better to just skip the call_user_func_array() when a context mismatch is known.