Implement exclusive attribute on dummy variables

[Pablete1234]

Adds an exclusive type of dummy variable, which limits how many different values (scope keys) there can be in a dummy variable.

exclusive supports values between 1 and 50. Please avoid using large values, if you simply don't care about the limit, do not specify one, and it'll just be infinite, at a smaller performance cost.

<variables>
  <variable id="last_scored" exclusive="1" scope="team" />
  <variable id="other" exclusive="2" scope="player" />
</variables>

In this example, the last_scored variable would, at most, have a value for one team. This in practice means that all other teams will always be reset to default whenever a team is set:
<set var="last_scored" value="1234"/> <- Sets the current scoped team value, and other teams are reset to default

For the other example, the "last 2" updated players will be kept, while players who got in "earlier" than that, are removed.
PlayerA triggers: <set var="other" value="other+1"/> <- Player A is added
PlayerB triggers: <set var="other" value="other+1"/> <- Player B is added
PlayerA triggers: <set var="other" value="other+1"/> <- Player A was already in, just gets value set to 2
PlayerC triggers: <set var="other" value="other+1"/> <- Player C is added, since the first added was A, A is replaced with C
Player D triggers: <set var="other" value="other+1"/> <- Player D is added, since the first added was B, B is replaced with D.

Realistically i don't see that much use in the second variant, but the exclusive="1" simplifies alot of use-cases that are otherways painful to reset, requiring multiple switch-scopes to get it sorted.
In this example, we want the team which gets the on-score action to add one, but the opposite team(s) to subtract one from their score, with exclusive it looks like this:

<variables>
  <score id="team_score" scope="team"/>
  <variable id="last_scored" exclusive="1" scope="team"/>
</variables>
<actions>
  <action id="on-score" scope="team">
    <set var="team_score" value="team_score+1"/>
    <set var="last_scored" value="1"/>
    <switch-scope inner="match">
      <switch-scope inner="team" filter="last_scored=0">
        <set var="team_score" value="team_score-1"/>
      </switch-scope>
    </switch-scope>
  </action>
</actions>

Previously, you'd need:

<variables>
  <score id="team_score" scope="team"/>
  <variable id="last_scored" scope="team"/>
</variables>
<actions>
  <action id="on-score" scope="team">
    <set var="team_score" value="team_score+1"/>
    <switch-scope inner="match">
      <switch-scope inner="team">
        <set var="last_scored" value="0"/>
      </switch-scope>
    </switch-scope>
    <set var="last_scored" value="1"/>
    <switch-scope inner="match">
      <switch-scope inner="team" filter="last_scored=0">
        <set var="team_score" value="team_score-1"/>
      </switch-scope>
    </switch-scope>
  </action>
</actions>

This is a nice to have as a pre-requisite for a potential future system for chat message interpolation of player/team names and score values

[cswhite2000]

Seems useful. I'm wondering if this should have some mechanism of unsettling a player's variable, or perhaps having the option of having filter-based ordering for which variable gets removed?
Minor note that your description says 1-100, but the code limits 1-50.

[Pablete1234]

Seems useful. I'm wondering if this should have some mechanism of unsettling a player's variable, or perhaps having the option of having filter-based ordering for which variable gets removed?

Realistically i only expect the "1" value to be used out there, but since it made sense to allow for larger i left the possibility open. Due to implementation details (for performance reasons) it is easy to always add in an order, because it never needs to check if the item is already in the "remove queue" or re-ordering the queue at all. If such needs are made relevant in the future we can explore having separate variable implementations that support those needs