Make it a public method: isPluginBeingUpgraded(). This method returns true if the plugin associated with the update checker is currently in the process of being updated.
This can be useful for plugins that hook into WordPress core to change how WordPress installs updates. For example, if you were using the "upgrader_pre_download" filter, you could call this method to verify that the update being downloaded is for your plugin and not another one.
Caution: The method is not guaranteed to be accurate.
The update checker uses class_exists in several ways:
- As a guard clause around `class Whatever` definitions. This ensures we don't try to define a class that has already been loaded by a different plugin. In this case, autoloading is not necessary because we already know how to load the class. Also, we *want to* load our version of that class if possible - the version that gets loaded by somebody else's autoloader might be different and incompatible.
- As a guard clause before `require` statements that include a class. This is conceptually the same as the previous example.
- To enable optional features if Debug Bar is active. The latest compatible version of Debug Bar doesn't use autoloading, so it would again be unnecessary in this case.
- Added experimental GitHub support. The new PucGitHubChecker subclass can check a GitHub repository for plugin updates. Depending on configuration, it will use either the latest release, the latest tag, or the specified branch. It can also automagically extract version details (description, changelog, etc) from a number of different locations - release names, plugin headers, readme.txt, changelog.md and more.
- The "slug" field of the metadata file is no longer used. The update checker will now use the slug passed to the class constructor, or generate a slug based on the plugin file name.
- Other minor changes to slug handling.
- Version bump to 2.0.
Yahnis Elsts
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