[wp-trac] [WordPress Trac] #38650: Provide some guidance on what conditionals can/should be used in default-filters.php

[WordPress Trac]

#38650: Provide some guidance on what conditionals can/should be used in default-
filters.php
----------------------------+---------------------
 Reporter:  helen           |       Owner:  jorbin
     Type:  enhancement     |      Status:  closed
 Priority:  low             |   Milestone:  6.7
Component:  Bootstrap/Load  |     Version:
 Severity:  minor           |  Resolution:  fixed
 Keywords:  has-patch       |     Focuses:  docs
----------------------------+---------------------

Comment (by devspace):

 In the `default-filters.php` file, which is typically part of WordPress,
 conditionals are used to add, remove, or modify filters and actions
 dynamically, based on specific conditions. Here's a brief guide on when
 and what conditionals to use:

 ### Common Conditionals
 1. **`is_admin()`**
    - Use this to check if the current request is for an admin page.
    - Example Use: Add/remove filters specific to the WordPress admin
 panel.
    ```php
    if (is_admin()) {
        // Admin-specific filters or actions
    }
    ```

 2. **`is_front_page()`**
    - This checks if the current page is the front page of the site.
    - Example Use: Add filters that apply only to the homepage.
    ```php
    if (is_front_page()) {
        // Homepage-specific filters
    }
    ```

 3. **`is_single()`**
    - This checks if a single post is being viewed.
    - Example Use: Customize post-related filters when viewing single
 posts.
    ```php
    if (is_single()) {
        // Post-specific filters
    }
    ```

 4. **`is_page()`**
    - Checks if the current page is a static page.
    - Example Use: Apply filters for static pages only.
    ```php
    if (is_page()) {
        // Page-specific filters
    }
    ```

 5. **`is_user_logged_in()`**
    - Use this to check if a user is logged in.
    - Example Use: Apply different filters for logged-in users versus non-
 logged-in users.
    ```php
    if (is_user_logged_in()) {
        // Filters for logged-in users
    }
    ```

 6. **`current_user_can( $capability )`**
    - Checks if the current user has a specific capability.
    - Example Use: Apply filters based on user roles.
    ```php
    if (current_user_can('edit_posts')) {
        // Filters for users who can edit posts
    }
    ```

 7. **`is_singular( $post_type )`**
    - Checks if the current query is for a single post of a specific post
 type.
    - Example Use: Apply filters for custom post types.
    ```php
    if (is_singular('product')) {
        // Product-specific filters
    }
    ```

 8. **`is_archive()`**
    - Checks if an archive page is being displayed.
    - Example Use: Modify filters specifically for archive pages.
    ```php
    if (is_archive()) {
        // Archive page filters
    }
    ```

 ### Use Case Examples
 - **Performance optimization**: You might add filters only in certain
 cases to avoid performance hits, such as applying heavy filters only to
 specific pages like single posts or archives.
 - **Role-based customization**: Use `current_user_can()` to add different
 filters for admins versus regular users.

 In general, conditionals in `default-filters.php` should be used to target
 specific contexts in which filters are needed, helping to optimize site
 performance and customize user experiences effectively.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/38650#comment:6>
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