Fuel question…

[AssumedPseudonym]

 I’m trying to access how much fuel is available in a fuel item. I can see in the XML that there’s a field called “data” in the <ItemType> tag, but is there a way to get hold of that value via tLISP?

[NMS]

The pteravore overlay appears to use (itmGetTypeData theItem).

[AssumedPseudonym]

 That is exactly what I was looking for, thanks. I never would have thought to have checked there. And there even appears to be a corresponding itmSetTypeData function. Score! ^.^

EDIT: So… how do I use itmSetTypeData to set that value? Trying to use it in the same manner as itmGetTypeData in the above example returns an “identifier expected” error, and (itmSetTypeData theItem 'data value) doesn’t access the same value.

[NMS]

Here's the most relevant part of the C code that handles those functions:

Code: Select all

		case FN_ITEM_GET_TYPE_DATA:
			{
			//	Because of backwards compatibility, if we only have one argument
			//	then we assume that we want type data.

			if (pArgs->GetCount() == 1)
				pResult = pCC->Link(pType->GetData(), 0, NULL);

			//	Otherwise, we get global data from the design type

			else
				{
				CString sData = pType->GetGlobalData(pArgs->GetElement(1)->GetStringValue());
				pResult = pCC->Link(sData, 0, NULL);
				}

			break;
			}

		case FN_ITEM_SET_GLOBAL_DATA:
			{
			CString sAttrib = pArgs->GetElement(1)->GetStringValue();
			if (sAttrib.IsBlank())
				{
				pResult = pCC->CreateNil();
				break;
				}

			CString sData = CreateDataFromItem(*pCC, pArgs->GetElement(2));
			pType->SetGlobalData(sAttrib, sData);
			pResult = pCC->CreateTrue();
			break;
			}

And some other relevant things:

Code: Select all

 		inline const CString &GetData (void) const { return m_sData; }

Code: Select all

ALERROR CItemType::OnCreateFromXML (SDesignLoadCtx &Ctx, CXMLElement *pDesc)

//	OnCreateFromXML
//
//	Load data from XML
...
	m_sData = pDesc->GetAttribute(DATA_ATTRIB);

So, I'd say you can't change the value of the built-in data field that's loaded from the XML.

But you can set your own data with (itmSetTypeData item 'variable value) and retrieve it with (itmGetTypeData item 'variable)

[AssumedPseudonym]

 Yeah, I already gathered as much, and even ticketed it on the Ministry. My major issue is that using the attribute argument in itmSetTypeData would wind up with me having to basically rewrite the entirety of the refueling code for the idea I had in mind — which, while doable, is something I’d really rather avoid. I’d prefer not to have to reinvent the wheel, as it were.
 …I was sort of expecting a block of C from you, heh. Thanks for doing the digging on that; there’s no way I could have made heads or tails of it, myself.

[NMS]

I was editing my post to be slightly more informative as you were posting yours.

You're welcome. I've found it interesting to search through the code. Downloading the source with the Git desktop client and using Notepad++'s find in files feature makes it reasonably practical to answer questions like this with a few searches. It's pretty amazing that one person could create a massive project like this involving three different languages (plus whatever's involved in compiling it).

Now that I think about it, it seems like it would be possible to change the code that loads the type from the XML so that it stores the data field using the same funtion as (itmSetTypeData). Then it would be changeable like any other data that's been added.