Recently the question (How to add add custom functions to a theme) was posed in最近的问题（如何添加添加自定义功能，以一个主题）中提出的 WordPress Support Forum在WordPress支持论坛 . 。 Personally I faced the same question when re-designing我个人面临着同样的问题时，重新设计 this site本网站 . 。 The following is a discussion of the option with the pros and cons.以下是讨论的选项与优点和缺点。

There are two solutions.有两个解决办法。
The first is to create a plugin which goes with the theme.首先是创建一个插件，其中有云与主题。 However the theme, when invoking functions defined in the plugin should check first for the availability of the function.不过主题时，引用所界定的职能的插件应该检查第一为可用的功能。 It should also provide a fallback option if the plugin is not available or has not been activated.它还应提供后备选项，如果插件是无法使用或尚未启用。 

 if(function_exists('your_function_name')) {     // Invoke your function: your_function_name()...如果（ function_exists （ ' your_function_name ' ） ） （ / /引用您的功能： your_function_name ()... else {     // Execute fallback option }否则， （ / /执行后备选项）

The advantages are:优势是：

  • The plugin can be independently managed.插件，可以独立管理。
  • The plugin can be reused for other purposes.该插件可以再用作其他用途。

The disadvantages are:弊端是：

  • It requires another additional step for the theme user to remember.它需要额外的步骤，另一个为主题，用户要记住。
  • It slightly complicates development and testing.它稍复杂的开发和测试。

The second solution to this problem would be to incorporate the functionaility in a php file (as usual) which resides in the theme directory.第二要解决这个问题将纳入functionaility在PHP文件（如常） ，其中居住在主题目录。 This file is included in header.php like:此文件是包含在header.php ，例如：
include (’your_php_file.php’); 包括（ ' your_php_file.php ' ） ;

Yes you may also require it for simplicity like:是您可能还需要它简单，例如：
require (’your_php_file.php’); 要求（ ' your_php_file.php ' ） ;

The advantage to this approach is simplicity of usage and deployment by end-users.的优势，这种做法是简单的使用情况和部署的最终用户。 It also simplifies development.它也简化了发展。

If the user later decides to switch to a different theme and yet wants to retain the functionality, he would have to re-purpose the custom code into a plugin.如果用户后来决定将切换到不同的主题，但要保留的功能，他将不得不重新目的的自定义代码成为一个插件。

In essence the reusability of the custom functionality determines the ideal location of the custom code.在本质上的可重用的自定义功能决定的理想地点的自定义代码。