layoutsextends

Layoutsextends is a templating pattern used in some web development and content management systems to let a layout extend another layout. It combines layout templates and inheritance to promote reuse and consistency while enabling page-specific customization.

In layoutsextends, a base layout defines common regions such as header, content, and footer. A child layout declares that it extends the base and provides content for named blocks. The rendering engine merges base and child, substituting blocks with the child’s content. This mechanism may also allow appending to regions or redefining nested blocks in more advanced implementations.

This pattern is used for sites with a shared shell and varying pages, with theming systems, and in component libraries that require a stable structure and flexible bodies. It supports maintaining a consistent chrome while allowing page or section variations.

Advantages include reduced duplication and easier maintenance; drawbacks can include potential complexity in inheritance chains and tighter coupling between layouts, which can complicate debugging and refactoring.

Example (conceptual): a base layout defines blocks header, content, and footer. A child layout extends the base and fills the content block with page text, optionally overriding the header to reflect page-specific branding.

Related concepts include template inheritance and block overriding in Django, Jinja, Twig, and other templating systems, as well as broader layout templating practices in various CMS and frontend frameworks.