PlantUML !include preprocessor?

I’m using lot of !include files in PlantUML diagrams to have clear sturcture and DRY.

== UML class diagram test with kroki
[plantuml, "diagram-classes", svg]
....
!include <src/style-presets.iuml>

class BlockProcessor
class DiagramBlock
class DitaaBlock
class PlantUmlBlock

BlockProcessor <|-- DiagramBlock
DiagramBlock <|-- DitaaBlock
DiagramBlock <|-- PlantUmlBlock
....

For local builds with plantuml.jar it works, but with remote server like PlantUML server or kroki it does not work. I understand that it is not wanted, because it will do preprocessing with knowlegde of PlantUML syntax and has to be updated etc.

Is there other solution to solve similar structural problems at client side?

[anb0s]

For using the Asciidoctor include derective i’ve to rework all the diagrams. It would be good to have a preprocessing task at client before sending it to the server. So at the end this would be good just to include the diagram files: e.g. presentation.adoc:

[plantuml, "diagram-classes", svg]
....
include::src/diagram-classes.puml[]
....

The diagram file itself includes other needed files.

src/diagram-classes.puml:

@startuml
!include <style-presets.iuml>

class BlockProcessor
class DiagramBlock
class DitaaBlock
class PlantUmlBlock

BlockProcessor <|-- DiagramBlock
DiagramBlock <|-- DitaaBlock
DiagramBlock <|-- PlantUmlBlock
@enduml

So the preprocessor should fetch all the files recursevly and avoid loading same files (include loop).

P.S.: similar was implemented in the vscode-plantuml plugin.

[Mogztter]

Sort of, the PlantUML preprocessor resolves !include directives in order to create a “standalone” diagram definition.

Unfortunately, it can’t resolve “complex” statements like %get_variable_value. Instead, the PlantUML preprocessor will try to read a file (using %get_variable_value("RELATIVE_INCLUDE")/C4.puml as path) on your local file system.

It’s tricky because it’s a preprocessor, so it cannot evaluate PlantUML syntax such as the if condition or the %get_variable_value function.

Do you send your diagrams to the public instance https://kroki.io or to a local instance?

If you want to use the built-in version of C4, I would recommend to use the following syntax:

!include <c4/C4_Context.puml>

In this case, the preprocessor will ignore the !include directive and Kroki server will resolve the !include directive using built-in C4 definition files.