Update AV1004: Use an interface rather than a base class to support multiple implementations#346
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dennisdoomen wants to merge 1 commit intodevelopfrom
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Update AV1004: Use an interface rather than a base class to support multiple implementations#346dennisdoomen wants to merge 1 commit intodevelopfrom
dennisdoomen wants to merge 1 commit intodevelopfrom
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Split from #298. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
bkoelman
reviewed
Mar 29, 2026
| severity: 3 | ||
| --- | ||
| If you want to expose an extension point from your class, expose it as an interface rather than as a base class. You don't want to force users of that extension point to derive their implementations from a base class that might have an undesired behavior. However, for their convenience you may implement a(n abstract) default implementation that can serve as a starting point. | ||
| If you want to expose an extension point from your class, expose it as an interface rather than as a base class. You don't want to force users of that extension point to derive their implementations from a base class that might have an undesired behavior. However, for their convenience you may implement an abstract default implementation that can serve as a starting point. |
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| If you want to expose an extension point from your class, expose it as an interface rather than as a base class. You don't want to force users of that extension point to derive their implementations from a base class that might have an undesired behavior. However, for their convenience you may implement an abstract default implementation that can serve as a starting point. | |
| If you want to provide an extension point for your class, expose an interface rather than a base class. You don't want to force alternative implementations to derive from your base class that might have an undesired behavior. However, for their convenience, you may provide an abstract default implementation as a starting point. |
Though I believe the last sentence is almost always a bad idea. And #302 advocates against it for a good reason:
Any change to the base class can unexpectedly break derived classes, and the inheritance hierarchy can become difficult to understand as it grows.
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This PR updates guideline AV1004.
It was split out of #298 so the change can be reviewed independently.
Files:
Part of the replacement for #298.