What would be the easiest way to create a "before taking" script?

[KVonGit]

I want to do something like this for an object's take script (or actually before its take script), but I'm 99.999% sure this would create an infinite loop as its take script.

this.cantake = true
if (HasScript(this, "beforetryingtaking")){
  do(this, "beforetringtaking")
}
// Check if the beforetryingtaking script set cantake to false before calling beforetaking
if(this.cantake) {
  if (HasScript(this, "beforetaking")){
    do(this, "beforetaking")
  }
}
// Check if anything has set cantake to false before trying to take
if(this.cantake) {
  // Can't do this! It will just call this script, creating an infinite loop
  DoTake(this)
}

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I think I'd have to modify DoTake to make things work smoothly.

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I'm trying to help port an Inform 7 game to Quest.

A few of the objects in this game use:

• before trying taking
• before taking
• after taking

Quest's takemsg is almost the same thing as "after taking" (as far as this game is concerned, anyway), but I'll have to add code to handle the "before" scripts. The thing is, it should still use the DoTake script once/if it makes it past "before trying taking" then "before taking", so it still runs all the checks before trying to actually take the object.

Before trying taking the lamp when the lamp is not carried by the player and the stick is carried by the player:
	say "You reach out with the stick and...".
	
Before taking the lamp when the location is the waterfall and the lamp is not carried by the player:
	if the stick is carried by the player:
		say "...you manage to get it under the handle just enough, and...";
	else:
		say "You can't reach it." instead.
		
After taking the lamp for the second time:
	say "Taken. Again. (Only a fool would drop such a thing in the first place!)".

---

>get lamp
You reach out with the stick and...

...you manage to get it under the handle just enough, and...

Taken. Again. (Only a fool would drop such a thing in the first place!)

>

---

There are about 20 objects in this game that use "before trying taking" and "before taking", too. So, I really would like to just modify DoTake, if possible.

[angelwedge]

I think the easiest way to do this would be including it in TestTakeGlobal.

Something like…

  <function name="TestTakeGlobal" parameters="object, prefix" type="boolean">
    // Existing behaviour of TestTakeGlobal, used to prevent player taking anything:
    if (HasString(game.pov, "notallowedtotake")) {
      msg (game.pov.notallowedtotake)
      return (false)
    }

    // Back up value of object.cannotbetaken, so that if beforetrytaking or before taking changes it
    //    we can revert to its original value later
    connotbetaken = object.cannotbetaken
    if (HasString (object, "beforetryingtaking")) {
      msg (prefix + object.beforetryingtaking)
      prefix = ""
    }
    else if (HasScript (object, "beforetryingtaking")) {
      do (object, "beforetryingtaking", QuickParams ("prefix", prefix))

      // Display a sensible message if beforetryingtaking has moved the object where we can't reach
      //    without giving a message
      if (Equal (cannottakemessage, object.cannottakemessage) and not ListContains (ScopeReachable (), object)) {
        msg (BlockingMessage (object, prefix))
        return (false)
      }
    }
    if (HasString (object, "cannottakemessage")) {
      if (not object.cannottakemessage = "") {
        msg (prefix + object.cannottakemessage)
      }
      object.cannottakemessage = cannottakemessage
      return (false)
    }
    if (HasString (object, "beforetaking")) {
      msg (prefix + object.beforetaking)
      prefix = ""
    }
    else if (HasScript (object, "beforetaking")) {
      do (object, "beforetaking", QuickParams ("prefix", prefix))
      if (Equal (cannottakemessage, object.cannottakemessage) and not ListContains (ScopeReachable (), object)) {
        msg (BlockingMessage (object, prefix))
        return (false)
      }
    }
    if (HasString (object, "cannottakemessage")) {
      if (not object.cannottakemessage = "") {
        msg (prefix + object.cannottakemessage)
      }
      object.cannottakemessage = cannottakemessage
      return (false)
    }
    else {
      return (true)
    }
  </function>

This is a bit more complex than it needs to be, but I think includes a few guards to avoid creating gotchas for users who make assumptions about how to use it.

An object's cannottakemessage attribute can contain a string specifying why an object can't be taken. If either of the beforetryingtaking or beforetaking scripts changes it, it will be reset to its previous value after being displayed. If it is set to a string, it will be displayed (with the object prefix, in case this occurs as part of a "take all" response) and taking the object will fail. If it is set to an empty string, it is assumed that the script already displayed a message and nothing will be printed.

If an object has a permenant cannottakemessage, it will keep on preventing the object from being taken. It can be overridden by the beforetryingtaking function; but if it is set to a different string it will return to its original value after the attempt fails.

I also made it so that if the beforetryingtaking or beforetaking scripts make the object unreachable but don't change the value of cannottakemessage, it will display the standard message for being unable to reach the object.

Hope that makes sense. I thought this seems like an interesting enough situation to merit a more flexible solution.

[KVonGit]

I didn't even know about TestTakeGlobal. :)

This looks great! I'll pop it into the game in a few hours. Thanks!

[KVonGit]

Well, this is freaking awesome! It definitely seems like the Quest way to handle things, and it seems to be more flexible than the way i7 handles things.

I'll be using this as posted in the future.

For this port, though, I think I'm going to do it a little differently (just for porting purposes), like this:

Click here to view "beforetaking test 1.aslx"

<!--Saved by Quest 5.9.9107.20739-->
<asl version="580">
  <include ref="English.aslx" />
  <include ref="Core.aslx" />
  <game name="beforetaking test 1">
    <gameid>9e13385d-c0ee-4fbc-9528-dabd5a79a41c</gameid>
    <version>0.0.1</version>
    <firstpublished>2024</firstpublished>
  </game>
  <object name="cavern">
    <inherit name="editor_room" />
    <isroom />
    <usedefaultprefix type="boolean">false</usedefaultprefix>
    <object name="player">
      <inherit name="editor_object" />
      <inherit name="editor_player" />
    </object>
    <exit alias="north" to="waterfall">
      <inherit name="northdirection" />
    </exit>
    <object name="lamp">
      <inherit name="editor_object" />
      <isroom type="boolean">false</isroom>
      <take />
      <beforetryingtaking type="script">
        if (this.parent = waterfall) {
          if (stick.parent = game.pov) {
            msg ("You reach out with the stick, and...")
          }
        }
      </beforetryingtaking>
      <beforetaking type="script">
        if (game.pov.parent = waterfall) {
          if (stick.parent = game.pov) {
            msg ("...you manage to get it under the handle just enough, and...")
            if (RandomChance(50)) {
              msg ("...it slips! You didn't get it!{once: (What are the odds?)}")
              this.notakingthisturn = true
            }
          }
          else {
            msg ("You can't reach it.")
            this.notakingthisturn = true
          }
        }
      </beforetaking>
    </object>
    <object name="stick">
      <inherit name="editor_object" />
      <isroom type="boolean">false</isroom>
      <take />
    </object>
  </object>
  <object name="waterfall">
    <inherit name="editor_room" />
    <isroom />
    <usedefaultprefix type="boolean">false</usedefaultprefix>
    <exit alias="south" to="cavern">
      <inherit name="southdirection" />
    </exit>
  </object>
  <function name="TestTakeGlobal" parameters="object, prefix" type="boolean">
    // "before trying" happens before everything
    if (HasScript(object, "beforetryingtaking")) {
      do (object, "beforetryingtaking")
      // If we set the object's "notakingthisturn" to true during its script,
      //   it cannot be taken for 1 turn, then "notakingthisturn" reverts to false
      if (GetBoolean(object, "notakingthisturn")) {
        object.notakingthisturn = false
        return (false)
      }
    }
    // This next block is from the original script
    if (HasString(game.pov, "notallowedtotake")) {
      msg (game.pov.notallowedtotake)
      return (false)
    }
    // this next block is new
    if (HasScript(object, "beforetaking")) {
      do (object, "beforetaking")
      // If we set the object's "notakingthisturn" to true during its script,
      //   it cannot be taken for 1 turn, then "notakingthisturn" reverts to false
      if (GetBoolean(object, "notakingthisturn")) {
        object.notakingthisturn = false
        return (false)
      }
    }
    return (true)
  </function>
</asl>

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PS

I realize this particular bit of this code could be handled in one script, but this bit was the only example I could use in full that wasn't 50 lines long. The other stuff actually utilizes everything properly.