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I've got a (simple) question regarding the UCI options and their current values:

  • I start my engine (e. g. Stockfish).

  • The console opens and I enter "uci" and press [Enter]. As a result, I get a list of options which the engine supports, with their min and max value, their type and their default setting. For example: option name Ponder type check default false

  • Let's say I change the following option: setoption name ponder value true

  • As I don't get an error, I expect that this option has been switched to true. But, when I now enter "uci" once more, I get the following output: option name Ponder type check default false

As you can see, it is exactly the same output that I already got when starting the engine and entered "uci" the very first time. I expect to see this: option name Ponder type check default false current value true

or something similar. Note: "current value true" was added by me, just to show what I expect.

Regardless which option I change, I never can query the current value. Why?

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  • I haven't read the UCI protocol closely enough to see if it has to respond to option queries. But setoption is not a query right?
    – qwr
    Commented Sep 13, 2022 at 2:47
  • Yes, "setoption" is the command to assign a value to an option. This works fine, but I'd like to query the current values of the available options and it seems not to be possible. Weird, isn't it?
    – Frank Kremer
    Commented Sep 13, 2022 at 22:27
  • The GUI is responsible for keeping track of these values
    – qwr
    Commented Sep 13, 2022 at 23:30
  • I agree, but nevertheless, I'd like to query the current value of an option. Let's say you change a couple of options and afterwards you want to see what everything has been changed. Unfortunately, this seems to be impossible, regardless of which chess engine you are using. None of them is capable tho show the current value of an option:(
    – Frank Kremer
    Commented Sep 14, 2022 at 15:47

1 Answer 1

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We cannot query on it as it is not supported by the protocol. However we can do something about it. I tried to maintain the uci protocol and added an issue with the following proposal.

Proposal 1

Support the command optionvalues. This command is sent to the engine. Some examples on engine reply format.

option name Threads value 2
option name Ponder value true
option name EvalFile value mynn.nnue

Feel free to post, comment or add your proposal in that repo.

I will inform the engine programmers community about this issue as well, so that they can support this on their engine.

By the way this is the usage of uci command.

* uci
    Tells the engine to use the uci (universal chess interface),
    this will be sent once as a first command after program boot
    to tell the engine to switch to uci mode.
    After receiving the uci command the engine must identify itself with the "id" command
    and send the "option" commands to tell the GUI which engine settings the engine supports if
    any. After that the engine should send "uciok" to acknowledge the uci mode. If no uciok is sent
    within a certain time period, the engine task will be killed by the GUI.

What is your use case why you query the current engine option values? From a gui's perspective, it can store option values that it sent to the engine.

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  • The proposal to add an "optionvalues" command is great! I wonder why this is not already implemented, yet! My use case is: I work with defferent engines and want to save the current option values for later use, to reapply them again.
    – Frank Kremer
    Commented Sep 16, 2022 at 16:46
  • This is not implemented, because you know already what you have inputted to the engine. As an example if I am designing a ui (user interface) if the user sends uci command to the engine, the ui can save this and then sends this to the engine. The engine will reply to the ui and the ui will show this info to the user. When the user asks again the value of option, the ui can just look up the value in the saved values.
    – ferdy
    Commented Sep 16, 2022 at 19:49
  • I agree that when an UI sent several setoption commands to the engine, the UI knows what it sent. But, as I understand, whenever I quit the engine and restart it later, the setoptions has to reapply, right? So, I'd like to query the current value of an option.
    – Frank Kremer
    Commented Sep 18, 2022 at 20:04
  • After quit and restart, the engine is set to use its default value. We would know the default value through the uci command. Example: option name Threads type spin default 1 min 1 max 512 The default is 1. It is also the current value.
    – ferdy
    Commented Sep 18, 2022 at 20:22

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