Irace callback feature

[rmartinsanta]

Summary

Add an optional iterationCallback scenario function that is invoked after each completed irace iteration.

This allows users to monitor tuning progress or collect intermediate results without modifying irace internals.

Callback interface

The callback receives the following named arguments:

• iteration: current iteration number.
• elites: elite configurations ordered from best to worst.
• progress: budget and timing information for the tuning run.

Callbacks should include ... as their final argument to remain compatible with additional arguments introduced by future irace versions. Example iteration_callback:

iteration_callback <- function(iteration, elites, progress, ...)
{
  message(
    "Iteration ", iteration,
    ": best configuration is ", elites[[".ID."]][1L]
  )
}

Arguments are passed by name, and a copy of the elite configurations is provided so callback mutations cannot affect the tuning run. Random-number generation inside the callback also
does not alter irace's RNG sequence.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.43%. Comparing base (7308aca) to head (bec759c).

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #98      +/-   ##
==========================================
+ Coverage   75.30%   75.43%   +0.12%     
==========================================
  Files          30       30              
  Lines        5087     5113      +26     
==========================================
+ Hits         3831     3857      +26     
  Misses       1256     1256              

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[MLopez-Ibanez]

Looks very good. Could you also add an entry to the NEWS.md file? I am in the middle of releasing the next version of irace, so this will go into irace 4.5. I will commit it as soon as irace 4.4.4 is released.

[MLopez-Ibanez]

I will also squash the multiple commits into a single one, so feel free to do that already.

[rmartinsanta]

Updated NEWS.md and squashed the commits, thanks for the fast response!

[MLopez-Ibanez]

@rmartinsanta Now that irace 4.4.4 has been released, could you rebase on top of the main branch and resolve the conflicts? They are probably due to updates to NEWS.md in main. I will then merge the PR.

[rmartinsanta]

Done!