Companion object in extensions
Reports incorrect companion objects' usage in extensions.
Kotlin companion object is always created once you try to load its containing class, and extension point implementations are supposed to be cheap to create. Excessive classloading in plugins is a huge problem for IDE startup.
Bad pattern:
Here KotlinDocumentationProvider
is an extension registered in plugin.xml
:
In this example JavaDocumentationProvider
will be loaded from disk once someone just calls new KotlinDocumentationProvider()
.
Kotlin companion objects in extension point implementation can only contain a logger and simple constants. Other declarations may cause excessive classloading or early initialization of heavy resources (e.g. TokenSet, Regex, etc.) when the extension class is loaded. Note, that even declarations marked with @JvmStatic
still produce an extra class for the companion object, potentially causing expensive computations.
Instead of being stored in companion object, these declarations must be top-level or stored in an object.
Move the declaration to top-level:
Before:
After:
Use INSTANCE
fieldName in plugin.xml
:
Before:
After:
Locating this inspection
- By ID
Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.
CompanionObjectInExtension- Via Settings dialog
Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.
New in 2023.3
Inspection Details | |
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By default bundled with: | |
Can be installed with plugin: | Plugin DevKit, 243.23126 |