Loop Issues in Developer Help

ID:674005
 
Apr 15 2012, 7:15 pm
(See the best response by DarkCampainger.)
Code:
        CraftUpdate(obj/S) // Outputs possible items that you can make from your input - S is the BTag of whatever you put in
            var/list/L = list() // Define L to be an empty list
            for(var/obj/Craftables/C in Craftables) // Loop through craftables
                L = C.Components // Set L to C's components
                for(var/X in L) // Loop through L
                    var/SA = S.Amount
                    if(X == S.BTag) // If an element in X has S's BTag
                        SA -- // Reduce SA by 1
                        if(SA < 0) // If SA is less than 0
                            break
                        else // If it's not less than 0
                            L -= X // Remove X from L
                    if(length(L) == 0) // If L is empty
                        src.OutputComponents += C // Add C to the player's output components
            return


Problem description:
The idea is that when I move an object from Input to inventory and back again to input, it doesn't seem to recreate the output possibilities. I think the problem is prolly with that SA variable I defined, but I don't know what went wrong.

Here is where I call CraftOutput() if needed.
        UpdateAll() // Update All - Updates the grids to output correct information
            var/X = 0 ; var/Y = 0 ; var/Z = 0
            src.OutputComponents.Cut(1) // This will clear the output list
            src << output(null, "Craft.Inventory") // These 3 lines clear the grids (So you don't get duplicates)
            src << output(null, "Craft.CraftInput")
            src << output(null, "Craft.CraftOutput")
            for(var/obj/A in src.Inventory)
                winset(src, "Craft.Inventory", "current-cell = [++X]")
                src << output(A, "Craft.Inventory")
            for(var/obj/B in src.InputComponents)
                winset(src, "Craft.CraftInput", "current-cell = [++Y]")
                src << output(B, "Craft.CraftInput")
                src.CraftUpdate(B)
            for(var/obj/C in src.OutputComponents)
                winset(src, "Craft.CraftOutput", "current-cell = [++Z]")
                src << output(C, "Craft.CraftOutput")
            winset(src, "Craft.Inventory", "cells = [X]")
            winset(src, "Craft.CraftInput", "cells = [Y]")
            winset(src, "Craft.CraftOutput", "cells = [Z]")
            return


Notes:

I did check to make sure the actual amount wasn't going down. It wasn't. The actual components list is also safe. What's going on?
#1 Apr 15 2012, 7:22 pm
Best response
Lugia319 wrote:
The actual components list is also safe.

L = C.Components // Set L to C's components
// ...
L -= X // Remove X from L


Are you sure?

Remember that lists are actually stored by reference (like objects), not value (like strings or numbers). So when you remove a value from 'L', you're actually removing it from the Craftable's Components list as well. You need to set 'L' to a copy of C.Components.
#2 Apr 15 2012, 7:24 pm
The reason I assumed that the components were safe was because I had another 2 lines in when I was testing it

else
  C.Components = initial(C.Components)


But I'll try setting it to a copy and seeing what happens.

EDIT: Making a fool out of me as always. You were right. I'll try to remember the list thing from now on.