Difference between revisions of "Modding Tutorials/Modifying defs"

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{{BackToTutorials}}
 
{{BackToTutorials}}
  
−
This tutorial shows you several ways to modify defs' (ThingDef, PawnKindDef) C# classes and alternatives to changing the XML format for them.<br/>
+
This tutorial shows you several ways to modify existing ''Defs'' and alternatives to changing the XML format for them.<br/>
  
−
There's several ways to achieve this goal. Three are listed here.<br/><br/>
+
There are several ways to achieve this goal. The table below is the [https://en.wikipedia.org/wiki/TL;DR TL;DR] version of this article. C# related operations are marked '''bold'''.<br/><br/>
 +
 
 +
{| class="wikitable"
 +
|-
 +
! Method !! Pros !! Cons !! When to use
 +
|-
 +
| Overwrite the Def || Braindead easy || So incompatible you gotta be braindead || When you don't care about the original, or anyone else
 +
|-
 +
| XPath change || Highly specific, highly compatible || Limited to XML-defined Defs || When you need to change a few XML values
 +
|-
 +
| Adding a '''(self-made)''' Comp || Very flexible, well-supported, highly-compatible || Does not work on every Def || When you want to add functionality
 +
|-
 +
| '''DefModExtension''' || Very simple, well-supported, highly-compatible || Static data || When you want to add fields/data
 +
|-
 +
| '''SubClassing''' || Fairly powerful, half the work is already done || Compatibility issues, not very flexible || When neither a Comp nor a DefModExtension works
 +
|-
 +
| '''Custom Def''' || Full control || Very specific to your mod || When the given Defs don't suffice for you
 +
|}
  
 
=Requirements=
 
=Requirements=
  
−
* [[Modding Tutorials/Decompiling source code|Decompiling source code]] is required.
+
* [[Modding Tutorials/XML Defs|Understanding Defs]] helps.
−
* This tutorial requires you to know [[Modding Tutorials/Writing custom code|how to write custom code]].
+
* For the C# portions:
−
* [[Modding Tutorials/Def classes|Introduction to Def Classes]] is highly recommended.<br/><br/>
+
** [[Modding Tutorials/Decompiling source code|Decompiling source code]] is required.
 +
** This tutorial requires you to know [[Modding Tutorials/Writing custom code|how to write custom code]].
 +
** [[Modding Tutorials/Def classes|Introduction to Def Classes]] is highly recommended.<br/><br/>
  
−
==Custom def class==
+
=Overwriting Defs=
 +
{{Main|Modding_Tutorials/Compatibility_with_defs}}
 +
If two mods share the same defName for a single type of ''Def'', the last mod wins. If mod A adds a ResearchDef with defName Pemmican and mod B also adds a ResearchDef with defName Pemmican, the game will use mod B's Pemmican.
 +
==Pros==
 +
Braindead easy.
  
−
This is where you create custom defs for your mod and C# code to go along with them.
+
==Cons==
 +
No compatibility.
  
−
The use of def classes is very popular in small mods: as long as the defs in the mod aren't overwriting core defs, it's very compatible.
+
==When to use==
 +
Not.
  
−
So if you have your own objects that you've created, and have C# code to go with them, it's fairly straightforward to add a custom def.  On the other hand, if you want to add a custom def to a core def that gets used everywhere in the code, it will be extremely difficult and you might be better off with a different approach.
+
=XPath=
 +
{{Main|Modding Tutorials/PatchOperations}}
 +
XPath allows you to change specific values of Defs (multiple in a single operation, if you want) across mods with surgical precision.
  
−
===Simple Example===
+
==Pros==
−
Suppose you add a new gun to RimWorld (assuming you're violent), that has a special feature.
+
Highly flexible, highly compatible.
  
−
Your XML might look something like this:
+
==Cons==
 +
Limited to Defs defined in XML (no meat, corpses or other generated Defs). More complex operations require more fiddly syntax.
  
−
<source lang="xml"><?xml version="1.0" encoding="utf-8"?>
+
==When to use==
−
<ThingDefs>
+
All the time.
−
<thingDef ParentName="BaseHumanGun" Class="myNamespace.MyCustomDef_ThingDef">
 
−
<defName>MyCoolNewGun</defName>
 
−
<thingClass>myNamespace.MyCoolNewGun</thingClass>
 
−
        <etc/>
 
−
<myNewFloat>1.1</myNewFloat>
 
−
<myNewBool>true</myNewBool>
 
−
<myNewThingDefList>
 
−
<li>Silver</li>
 
−
<li>Pistol</li>
 
−
</myNewThingDefList>
 
−
</thingDef>
 
−
</ThingDefs></source>
 
  
−
Two things were added to the XML for the custom defs: the Class="myNamespace.MyCustomDef_ThingDef" and the new definitions.
+
=Adding a (self-made) Comp=
 +
{{Main|Modding Tutorials/ThingComp}}
 +
ThingComps are like little modules you can add to any ThingWithComp to give them added functionality.
  
−
Corresponding C# code might look like this:
+
===Pros===
 +
Very flexible, well-supported and highly-compatible. There are many ready-made (example) Comps available that can be employed to do a wide variety of things.
  
−
<source lang="csharp">using RimWorld;
+
===Cons===
−
using System;
+
Not suited for every type of functionality.
−
using System.Collections.Generic;
 
−
using System.Diagnostics;
 
−
using System.Linq;
 
−
using UnityEngine;
 
  
 +
===When to use===
 +
When you want to add functionality, non-static data or behaviour.
  
−
namespace myNamespace
+
=DefModExtensions=
−
{
+
{{Main|Modding Tutorials/DefModExtension}}
−
public class MyCustomDef_ThingDef : ThingDef // Here we are adding our custom defs
+
DefModExtensions can be seen as a way to add fields to Defs.
−
{
 
−
public float myNewFloat;
 
  
−
public bool myNewBool;
+
===Pros===
 +
Very simple, very lightweight, highly compatible.
  
−
public List<ThingDef> myNewThingDefList = new List<ThingDef>();
+
===Cons===
−
}
+
Static data only.
−
public class MyCoolNewGun : etc //etc etc
 
−
{
 
−
  //etc
 
−
}
 
−
}</source>
 
  
−
And now that that exists you can call on it with any ThingDef as input like so:<br/>
+
===When to use===
 +
When you want to add (static) fields/data to Defs.
  
−
<source lang="csharp">
+
=Subclassing=
−
  // maybe var weapon=new myNamespace.MyCoolNewGun();
+
{{Main|Modding_Tutorials/Def_classes}}
−
  // or maybe a function was called with a parameter "weapon"
+
Inherit from a Def and explicitly tell RimWorld to use that specific Type.
  
−
  if (weapon as myNamespace.MyCoolNewGun != null) // make sure it actually IS a MyCoolNewGun, HAS the code, etc:
+
==Pros==
−
  {
+
They're you're own Type, so you can extend their functionality until your heart is content.
−
      // use the thingdef:
 
−
      var def = weapon.def as myNamespace.MyCustomDef_ThingDef;
 
−
      var theFloat = def.myNewFloat;
 
  
−
      // or access directly:
+
==Cons==
−
      var myBool = ((myNamespace.MyCustomDef_ThingDef)weapon.def).myNewBool;
+
* Still bound to the base Def without access to its private methods
−
      //     this will throw an exception if somehow the weapon isn't a MyCoolNewGun!
+
* Using them requires a lot of casting
 +
* Only one custom class per Def
 +
* They don't offer a lot of extra functionality over DefModExtensions or [https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/extension-methods C# Extension methods]
  
−
      // use the defs, etc
+
==When to use==
−
      // this works in beta 0.18.1722
+
When neither a Comp nor a DefModExtension works.
−
  }
 
−
</source>
 
  
 +
=Custom Def=
 +
{{Main|Modding Tutorials/Def_classes}}
 +
(Optionally) inherit from a Def and tell RimWorld to use your custom Def.
  
−
===Further Example===
+
==Pros==
−
You might want to add a whole class of guns with this new feature:
+
Fully your own Type, complete control. No incompatibility issues, because they're all yours.
  
−
Your XML might look something like this:
+
==Cons==
 +
Implementation from scratch.
  
−
<source lang="xml"><?xml version="1.0" encoding="utf-8"?>
+
==When to use==
−
<ThingDefs>
+
If your Def is really unique to your mod or specific goal.
−
<thingDef Name="MyCoolNewGun" ParentName="BaseHumanGun" Class="myNamespace.MyCustomDef_ThingDef" Abstract="true">
 
−
<thingClass>myNamespace.MyCoolNewGun</thingClass>
 
−
        <etc/>
 
−
<myNewFloat>1.1</myNewFloat>
 
−
<myNewBool>true</myNewBool>
 
−
<myNewThingDefList>
 
−
<li>Silver</li>
 
−
<li>Pistol</li>
 
−
</myNewThingDefList>
 
−
</thingDef>
 
  
−
<thingDef ParentName="MyCoolNewGun">
+
=Other ways=
−
<defName>MyCoolNewPistol</defName>
+
Sometimes creative, sometimes hacky:
−
<myNewFloat>2.2</myNewFloat>
+
==Checking for tags==
−
</thingDef>
 
  
−
<thingDef ParentName="MyCoolNewGun">
+
Instead of using custom defClasses and comps you could also use tags. This is especially useful for lightweight features and simple compatibility.<br/><br/>
−
<defName>MyCoolWaterPistol</defName>
 
−
<myNewBool>false</myNewBool>
 
−
<etc />
 
−
</thingDef>
 
−
</ThingDefs></source>
 
  
−
Each will inherit the parent's def class and link in with your code, and you can have a whole class of things using your cool new weapon mod.
+
Some tags are never used by a certain Thing such as ApparelTag on a Building. If a tag is never used it doesn't throw an error and therefore you could introduce as many useless tags as you want to a mod without the game complaining. When other mods check for these tags they can also do it without a problem. This way you could add tags of whatever name you want and let others check for this tag for compatibility.<br/><br/>
−
 
 
−
===When Not To Use It===
 
−
 
 
−
There are two big catches:
 
−
 
 
−
#  If you modify an existing definition to use your class, and someone else does too, there might be mod conflicts.  Oops.
 
−
#  Your defs only work for your own code. An example:
 
−
 
 
−
====Problem Example====
 
−
''The following method shows you '''why not to use''' custom defs. In some cases you could attempt to use this method but it's generally considered the least favourable way to deal with things.''
 
−
 
 
−
For this example we're gonna '''try to''' change the <race> tag to contain more tags. The value of these tags isn't exactly important to this example.
 
−
 
 
−
<source lang="xml"><?xml version="1.0" encoding="utf-8"?>
 
−
<ThingDefs>
 
−
<thingDef Name="BaseRace" Class="myNamespace.ThingDefWithCustomRaceProps"><!-- May not be needed in recent versions-->
 
−
</thingDef>
 
−
 
 
−
<thingDef Name="BaseAnimalRace" ParentName="BaseRace" Class="myNamespace.ThingDefWithCustomRaceProps"><!-- may not be needed -->
 
−
</thingDef>
 
−
 
 
−
<thingDef ParentName="BaseAnimalRace" Class="myNamespace.ThingDefWithCustomRaceProps">
 
−
<race Class="myNamespace.RacePropertiesCustom">
 
−
<myNewFloat>1.1</myNewFloat>
 
−
<myNewBool>true</myNewBool>
 
−
<myNewThingDefList>
 
−
<li>Silver</li>
 
−
<li>Pistol</li>
 
−
</myNewThingDefList>
 
−
</race>
 
−
</thingDef>
 
−
</ThingDefs></source><br/>
 
−
 
 
−
(earlier versions) Without assigning the Class to each thingDef inheriting from and being inherited by a certain thingDef with a certain Class, '''the mod will cause errors'''.
 
−
 
 
−
Now for the code we will have to create two C# classes, namely myNamespace.ThingDefWithCustomRaceProps and myNamespace.RacePropertiesCustom:
 
−
 
 
−
<source lang="csharp">using RimWorld;
 
−
using System;
 
−
using System.Collections.Generic;
 
−
using System.Diagnostics;
 
−
using System.Linq;
 
−
using UnityEngine;
 
−
 
 
−
 
 
−
namespace myNameSpace
 
−
{
 
−
public class ThingDefWithCustomRaceProps : ThingDef
 
−
{
 
−
new public RacePropertiesCustom race; /* requires the new keyword to overwrite the existing race */
 
−
}
 
−
}</source><br/>
 
−
 
 
−
And for the RacePropertiesCustom we make the following script:<br/>
 
−
 
 
−
<source lang="csharp">using RimWorld;
 
−
using System;
 
−
using System.Collections.Generic;
 
−
using System.Diagnostics;
 
−
using UnityEngine;
 
−
 
 
−
namespace myNameSpace
 
−
{
 
−
public class RacePropertiesCustom : RaceProperties
 
−
{
 
−
public float myNewFloat;
 
−
 
 
−
public bool myNewBool;
 
−
 
 
−
public List<ThingDef> myNewThingDefList = new List<ThingDef>();
 
−
}
 
−
}</source><br/>
 
−
 
 
−
One might think that's all required to make it work. However!
 
−
 
 
−
Wherever the race variable tag is called in the game's code, it's called like <code>((ThingDef)someVariable).race.someMethod()</code>.  It's NOT calling your code!  It's calling the base game's code.
 
−
 
 
−
Everywhere you need someMethod() to use your code, you need to cast the race:  ThingDefWithCustomRaceProps like <code>(ThingDefWithCustomRaceProps)((ThingDef)someVariable).race.someMethod()</code>.  '''EVERY''' single time.  It means copying and rewriting large portions of code, finding out they're called by certain other methods that also require the same treatment to call the new custom method to fix the custom thingDef class you made.
 
  
−
If your mod is restricted to something very small in scope, this might be okay.  But if it affects a large part of the game...you will have to do a lot of work to make it fit, and you might want to go another route.
+
===Pros===
 +
Lightweight, easy.
  
 +
===Cons===
 +
Risk of potential side-effects. Kinda hacky.
  
 +
==Changing the class used by the Def==
 +
A lot of ''Defs'' have a field entry that specifies the C# class they are tied to. For instance, the ''GameConditionDef'' for the Eclipse has a ''conditionClass'' of ''GameCondition_Eclipse''. Modders who wish to add some sparkles to the Eclipse could create a new GameCondition class called ''GameCondition_EclipseWithSparkles'' and use XPath to change the conditionClass to MyNameSpace.GameCondition_EclipseWithSparkles.
  
−
===Older Versions===
+
===Pros===
−
***NOTE: This seems to work fine in 0.18.1722, so you can ignore this section***
+
Pretty easy. Keeps most values of the original Def intact as well.
  
−
Def classes require a pretty hefty overhaul of XML code to work. First of all you will have to change anything in the inheritance to refer to the same class:<br/>
+
===Cons===
−
 
+
Subverts any Harmony patches on the original Class, so potential issues with compatibility.
−
<source lang="xml"><?xml version="1.0" encoding="utf-8"?>
 
−
<ThingDefs>
 
−
<thingDef Name="BaseThing" Class="myNamespace.myCustomClass">
 
−
</thingDef>
 
−
 
 
−
<thingDef Name="BaseSpecificThing" ParentName="BaseThing" Class="myNamespace.myCustomClass">
 
−
</thingDef>
 
−
 
 
−
<thingDef ParentName="BaseSpecificThing" Class="myNamespace.myCustomClass">
 
−
</thingDef>
 
−
</ThingDefs></source><br/>
 
−
 
 
−
And in case you have more thingDefs which require the changes that come with myNamespace.myCustomClass you'll have to set all of their classes for it to work.<br/>
 
−
Applied to core defs this way of doing things introduces incompatibilities with other mods that modify the same def. Creating compatibility patches is inevitable.<br/><br/>
 
−
 
 
−
On the plus side you make it possible to change the root thingDef tags. In most cases you don't need this but certain things such as Pawn code might have no alternatives.<br/><br/>
 
−
 
 
−
==Custom comp class==
 
−
 
 
−
Comp classes are a more advanced method of introducing compatibility to mods. Large mods might prefer comps to defs because it requires less XML editing in most cases. Along with that it's possible to inject comps into almost everything (because almost everything inherits from ThingWithComps) without having to change the comp while defs require a new class for each SomeDef they overwrite (E.g PawnKindDef and ThingDef require different classes)<br/><br/>
 
−
 
 
−
===Pros and cons===
 
−
 
 
−
Comps are easier to add than defClasses and can be injected by C# code. It's lighter on the XML code (doesn't require inheritance to be consistent) and C# code in most cases because it's more of a contained system. There's many hooks implemented which call for C# comp classes, such as CompTick() and PostDestroy(). Just like defs they can introduce incompatibilities. Adding another mod's comps requires the game to have both mods loaded, which can be a problem. Implementing smarter injection might fix this<sup>[?]</sup> in case a mod isn't loaded, but it's not possible to guarantee that the comp is actually added.<br/><br/>
 
−
 
 
−
===Method===
 
−
 
 
−
==Checking for tags==
 
−
 
 
−
Instead of using custom defClasses and comps you could also use tags. This is especially useful for lightweight features and simple compatibility.<br/><br/>
 
−
 
 
−
===Pros and cons===
 
−
 
 
−
Some tags are never used by a certain Thing such as ApparelTag on a Building. If a tag is never used it doesn't throw an error and therefore you could introduce as many useless tags as you want to a mod without the game complaining. When other mods check for these tags they can also do it without a problem. This way you could add tags of whatever name you want and let others check for this tag for compatibility.<br/><br/>
 
  
−
===Method===
+
==Harmony patching==
 +
{{Main|Modding Tutorials/Harmony}}
 +
If you still want to use Harmony in the face of all these alternatives, you might have fallen for the [https://exceptionnotfound.net/the-golden-hammer-anti-pattern-primers/ Golden Hammer Design Pattern]. But sure, go ahead.
  
 
=See also=
 
=See also=

Latest revision as of 13:16, 5 February 2019

< Modding Tutorials

This tutorial shows you several ways to modify existing Defs and alternatives to changing the XML format for them.

There are several ways to achieve this goal. The table below is the TL;DR version of this article. C# related operations are marked bold.

Method Pros Cons When to use
Overwrite the Def Braindead easy So incompatible you gotta be braindead When you don't care about the original, or anyone else
XPath change Highly specific, highly compatible Limited to XML-defined Defs When you need to change a few XML values
Adding a (self-made) Comp Very flexible, well-supported, highly-compatible Does not work on every Def When you want to add functionality
DefModExtension Very simple, well-supported, highly-compatible Static data When you want to add fields/data
SubClassing Fairly powerful, half the work is already done Compatibility issues, not very flexible When neither a Comp nor a DefModExtension works
Custom Def Full control Very specific to your mod When the given Defs don't suffice for you

Requirements[edit]

Overwriting Defs[edit]

Main article: Modding_Tutorials/Compatibility_with_defs

If two mods share the same defName for a single type of Def, the last mod wins. If mod A adds a ResearchDef with defName Pemmican and mod B also adds a ResearchDef with defName Pemmican, the game will use mod B's Pemmican.

Pros[edit]

Braindead easy.

Cons[edit]

No compatibility.

When to use[edit]

Not.

XPath[edit]

Main article: Modding Tutorials/PatchOperations

XPath allows you to change specific values of Defs (multiple in a single operation, if you want) across mods with surgical precision.

Pros[edit]

Highly flexible, highly compatible.

Cons[edit]

Limited to Defs defined in XML (no meat, corpses or other generated Defs). More complex operations require more fiddly syntax.

When to use[edit]

All the time.

Adding a (self-made) Comp[edit]

Main article: Modding Tutorials/ThingComp

ThingComps are like little modules you can add to any ThingWithComp to give them added functionality.

Pros[edit]

Very flexible, well-supported and highly-compatible. There are many ready-made (example) Comps available that can be employed to do a wide variety of things.

Cons[edit]

Not suited for every type of functionality.

When to use[edit]

When you want to add functionality, non-static data or behaviour.

DefModExtensions[edit]

Main article: Modding Tutorials/DefModExtension

DefModExtensions can be seen as a way to add fields to Defs.

Pros[edit]

Very simple, very lightweight, highly compatible.

Cons[edit]

Static data only.

When to use[edit]

When you want to add (static) fields/data to Defs.

Subclassing[edit]

Main article: Modding_Tutorials/Def_classes

Inherit from a Def and explicitly tell RimWorld to use that specific Type.

Pros[edit]

They're you're own Type, so you can extend their functionality until your heart is content.

Cons[edit]

  • Still bound to the base Def without access to its private methods
  • Using them requires a lot of casting
  • Only one custom class per Def
  • They don't offer a lot of extra functionality over DefModExtensions or C# Extension methods

When to use[edit]

When neither a Comp nor a DefModExtension works.

Custom Def[edit]

Main article: Modding Tutorials/Def_classes

(Optionally) inherit from a Def and tell RimWorld to use your custom Def.

Pros[edit]

Fully your own Type, complete control. No incompatibility issues, because they're all yours.

Cons[edit]

Implementation from scratch.

When to use[edit]

If your Def is really unique to your mod or specific goal.

Other ways[edit]

Sometimes creative, sometimes hacky:

Checking for tags[edit]

Instead of using custom defClasses and comps you could also use tags. This is especially useful for lightweight features and simple compatibility.

Some tags are never used by a certain Thing such as ApparelTag on a Building. If a tag is never used it doesn't throw an error and therefore you could introduce as many useless tags as you want to a mod without the game complaining. When other mods check for these tags they can also do it without a problem. This way you could add tags of whatever name you want and let others check for this tag for compatibility.

Pros[edit]

Lightweight, easy.

Cons[edit]

Risk of potential side-effects. Kinda hacky.

Changing the class used by the Def[edit]

A lot of Defs have a field entry that specifies the C# class they are tied to. For instance, the GameConditionDef for the Eclipse has a conditionClass of GameCondition_Eclipse. Modders who wish to add some sparkles to the Eclipse could create a new GameCondition class called GameCondition_EclipseWithSparkles and use XPath to change the conditionClass to MyNameSpace.GameCondition_EclipseWithSparkles.

Pros[edit]

Pretty easy. Keeps most values of the original Def intact as well.

Cons[edit]

Subverts any Harmony patches on the original Class, so potential issues with compatibility.

Harmony patching[edit]

Main article: Modding Tutorials/Harmony

If you still want to use Harmony in the face of all these alternatives, you might have fallen for the Golden Hammer Design Pattern. But sure, go ahead.

See also[edit]

Retrieved from "https://rimworldwiki.com/index.php?title=Modding_Tutorials/Modifying_defs&oldid=62526"