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GG网络技术分享 2025-03-18 16:12 3
I\'ve just started learning Wordpress and going through standard/default themes. If i have understood filters idea correctly, before we can apply them we need to add callback functions via add_filter($hook, $callback, $args). However looking at the \'twentyseventeen\' theme i can\'t see those declaration for twentyseventeen_starter_content and it is used then with: $starter_content = apply_filters( \'twentyseventeen_starter_content\', $starter_content ); (file functions.php) and twentyseventeen_front_page_sections - $num_sections = apply_filters( \'twentyseventeen_front_page_sections\', 4 ); (file front-page.php). What am i missing and how does it work without setting callback functions?
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功能建议我刚刚开始学习Wordpress并浏览标准/默认主题。 如果我已正确理解过滤器的想法，在我们应用它们之前，我们需要通过 add_filter（$ hook，$ callback，$ args）</ code>添加回调函数。 然而，看看\'二十七\'主题，我无法看到 twentyseventeen_starter_content </ code>的声明，然后使用它： $ starter_content = apply_filters（\'twentyseventeen_starter_content\'，$ starter_content）; </ code >（file functions.php）和 twentyseventeen_front_page_sections </ code> - $ num_sections = apply_filters（\'twentyseventeen_front_page_sections\'，4）; </ code>（file front-page.php）。 我缺少什么，如果没有设置回调函数它是如何工作的？</ p>
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apply_filters runs all the callbacks attached to it by add_filter to the same hook/tag. If there are no callbacks attached to that hook/tag it returns the second parameter (which is the value beng filtered) of the apply_filters. Therefore apply_filters( \'twentyseventeen_front_page_sections\', 4 ); will return 4 if there are no add_filter(\'twentyseventeen_front_page_sections\', \'callbackfunc\');. Else it will return the result of the add_filter callback with the highest priority after going through all callbacks.
Priorities are set in the add_filter as the third parameter.
I don\'t know if this what you were looking for but i thought it might give you a better understanding.
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