Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
tutorials:advanced:task_trees [2015/06/29 13:40] – [Using projection runs to guide plan transformation] mpomarlan | tutorials:advanced:task_trees [2020/09/17 14:09] (current) – [Plan transformations: task trees, code replacement, and serialization] gkazhoya | ||
---|---|---|---|
Line 1: | Line 1: | ||
====== Plan transformations: | ====== Plan transformations: | ||
- | **Description: | + | **Disclaimer: |
+ | |||
+ | **Description: | ||
===== CRAM task trees ===== | ===== CRAM task trees ===== | ||
Line 284: | Line 286: | ||
<code lisp> | <code lisp> | ||
(swank: | (swank: | ||
- | (cram-projection: | ||
(in-package :cpl-impl) | (in-package :cpl-impl) | ||
+ | (cram-projection: | ||
(def-top-level-cram-function tryprj () | (def-top-level-cram-function tryprj () | ||
Line 332: | Line 334: | ||
* BODY, a list of S-expressions that should be run. The macro return value is the return value of BODY. | * BODY, a list of S-expressions that should be run. The macro return value is the return value of BODY. | ||
- | Just like with-transformative-failure-handling, | + | Just like with-transformative-failure-handling, |
+ | |||
+ | ===== Changing parameters with plan transformation ===== | ||
+ | |||
+ | Remember one of the previous laws of the task tree: | ||
+ | |||
+ | //When a task tree node is run, the value of PARAMETERS in either CODE or (car CODE-REPLACEMENTS) is set to the value of the parameters at the moment of the function call.// | ||
+ | |||
+ | This means that, typically, you can't change parameters through plan transformation as previously implemented in CRAM. However, it's useful to distinguish two types of parameters for a cram-function: | ||
+ | |||
+ | * " | ||
+ | * " | ||
+ | |||
+ | To support " | ||
+ | |||
+ | <code lisp> | ||
+ | (swank: | ||
+ | |||
+ | (defparameter par-1 1) ;; just a couple variables to give some ' | ||
+ | (defparameter par-2 1) | ||
+ | |||
+ | (cpl-impl: | ||
+ | (format T " | ||
+ | (format T " | ||
+ | (format T "PTR parameter is (~a)~%Will now fail, so as to trigger plan transformation.~%" | ||
+ | (cpl:fail ' | ||
+ | |||
+ | (defun compatible-ptr (P &rest args) | ||
+ | (format T " | ||
+ | (format T " | ||
+ | (format T "PTR parameter is (~a)~%Done!~%" | ||
+ | |||
+ | (cpl-impl: | ||
+ | (cpl-impl: | ||
+ | ((cpl-impl: | ||
+ | (let ((code-path (cpl-impl:: | ||
+ | (format t "Will replace code now (and switch the ptr-parameter) ...~%" | ||
+ | (cpl-impl: | ||
+ | (cpl-impl: | ||
+ | (setf par-1 (+ par-1 par-2)) | ||
+ | (setf par-2 (- par-1 par-2)) | ||
+ | (example-ptr " | ||
+ | </ | ||
+ | |||
+ | Of these, example-ptr is the " | ||
+ | |||
+ | ptr-cram-functions are a bit peculiar. When you call them the first time they behave like regular cram functions, and take their parameters from the ones you supplied. When you call them again (meaning, when there' | ||
+ | |||
+ | To actually change the compile time parameter in a node, notice the extra &key parameter in replace-task-code: | ||
+ | |||
+ | <code lisp> | ||
+ | (cpl-impl: | ||
+ | </ | ||
+ | |||
+ | By default the : | ||
+ | |||
+ | In our example here, the compile-time parameter is a string. It can however be anything, including a struct or a list, for when you need to pass on several objects through plan transformation. | ||
+ | |||
+ | Let's run the top-level function and see what happens (trace below shows a copy-paste from the repl window) ... | ||
+ | |||
+ | <code lisp> | ||
+ | CL-USER> (try-ptr) | ||
+ | Inside example-ptr. | ||
+ | Received arguments (2 1 0) | ||
+ | PTR parameter is (Apples) | ||
+ | Will now fail, so as to trigger plan transformation. | ||
+ | Will replace code now (and switch the ptr-parameter) ... | ||
+ | Inside compatible-ptr. | ||
+ | Received arguments (3 2 0) | ||
+ | PTR parameter is (Oranges) | ||
+ | Done! | ||
+ | NIL | ||
+ | CL-USER> (try-ptr) | ||
+ | Inside compatible-ptr. | ||
+ | Received arguments (5 3 0) | ||
+ | PTR parameter is (Oranges) | ||
+ | Done! | ||
+ | NIL | ||
+ | CL-USER> (try-ptr) | ||
+ | Inside compatible-ptr. | ||
+ | Received arguments (8 5 0) | ||
+ | PTR parameter is (Oranges) | ||
+ | Done! | ||
+ | NIL | ||
+ | </ | ||
+ | |||
+ | Notice how the transformed plan persists between plan runs, including the compile-time parameter, even though the run-time parameters change as expected. | ||
===== Task tree serialization ===== | ===== Task tree serialization ===== | ||