File Load Plugin

Source code on GitHub.

Plugin Class

cx::FileLoadPlugin

This plugin provides the ability to load files into CLIPS using batch* and load* through configuration values.

Configuration

pkg_share_dirs:

Type	Default
string vector	[]

Description

When specifying relative paths, look at the share directories of the listed packages to resolve them (in the specified order).

load:

Type	Default
string vector	[]

Description

Specify files to load using CLIPS load* command when the plugin is loaded. Supports absolute paths or relative paths using the share directories specified above.

batch:

Type	Default
string vector	[]

Description

Specify files to load using CLIPS batch* command when the plugin is loaded. This happens after the files specified in load are loaded. Supports absolute paths or relative paths using the share directories specified above.

cleanup_batch:

Type	Default
string vector	[]

Description

Specify files to load using CLIPS batch* command when the plugin is unloaded. This may be used to clean up all loaded content to gracefully undo whatever was loaded in before. Supports absolute paths or relative paths using the share directories specified above.

Features

This plugin injects the user-defined code into the CLIPS environments and has no other effects.

For the difference between load* and batch* please consult the CLIPS Basic Programming Guide (PDF).

Note

It is recommended to use load over batch whenever possible due to the superior error handling of load. E.g., when using batch, a missing closing parenthesis ) may lead to a silent failure as CLIPS treats this as an uncompleted command and waits for another closing parenthesis to appear before actually processing the input.

Usage Example

A minimal working example is provided by the cx_bringup package. Run it via:

ros2 launch cx_bringup cx_launch.py manager_config:=plugin_examples/file_load.yaml

Configuration

File cx_bringup/params/plugin_examples/file_load.yaml.

clips_manager:
  ros__parameters:
    environments: ["cx_file_load"]
    cx_file_load:
      plugins: ["files"]
      watch: ["facts", "rules"]

    files:
      plugin: "cx::FileLoadPlugin"
      pkg_share_dirs: ["cx_bringup"]
      load: ["clips/plugin_examples/file-load.clp"]
      batch: ["clips/plugin_examples/file-load-batch.clp"]
      cleanup_batch: ["clips/plugin_examples/file-load-cleanup-batch.clp"]

Code

File cx_bringup/clips/plugin_examples/file-load.clp.

(defrule hello-world
   (not (hello))
   =>
   (printout green "Hello world" crlf)
   (assert (hello))
)
(defrule goodbye-world
   (executive-finalize)
   =>
   (printout blue "Goodbye world" crlf)
)

File cx_bringup/clips/plugin_examples/file-load-batch.clp.

(printout yellow "batch" crlf)

File cx_bringup/clips/plugin_examples/file-load-cleanup-batch.clp.

; file-load-cleanup-batch.clp

(printout yellow "cleanup batch" crlf)
(undefrule hello-world)
(undefrule goodbye-world)
(do-for-all-facts ((?h hello))
  (retract ?h)
)