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Patch splitted and ported over from PR #118 
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‎GameData/KSPCommunityFixes/Settings.cfg‎

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// To use add `Description` attribute to the field.
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KSPFieldEnumDesc = false
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// Allow dynamically defining additional BaseFields on a Part or PartModule and having the backing
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// field for that BaseField in another class / instance than the targetted Part or Module. Look for
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// the examples and documentation in the patch source.
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BaseFieldListUseFieldHost = true
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// ##########################
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// Localization tools
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// ##########################

‎KSPCommunityFixes/KSPCommunityFixes.csproj‎

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<?xml version="1.0" encoding="utf-8"?>
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<?xml version="1.0" encoding="utf-8"?>
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<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
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<Import Project="..\packages\Krafs.Publicizer.2.2.1\build\Krafs.Publicizer.props" Condition="Exists('..\packages\Krafs.Publicizer.2.2.1\build\Krafs.Publicizer.props')" />
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<Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
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<Compile Include="Library\LocalizationUtils.cs" />
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<Compile Include="Library\Numerics.cs" />
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<Compile Include="Library\ObjectPool.cs" />
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<Compile Include="Modding\BaseFieldListUseFieldHost.cs" />
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<Compile Include="Modding\KSPFieldEnumDesc.cs" />
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<Compile Include="Modding\ModUpgradePipeline.cs" />
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<Compile Include="Performance\ForceSyncSceneSwitch.cs" />

‎KSPCommunityFixes/Modding/BaseFieldListUseFieldHost.cs‎

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using HarmonyLib;
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using System;
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/*
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The purpose of this patch if to allow BaseField and associated features (PAW controls, persistence, etc) to work when
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a custom BaseField is added to a BaseFieldList (ie, a Part or PartModule) with a host instance other than the BaseFieldList
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owner. This allow to dynamically add fields defined in another class to a Part or PartModule and to benefit from all the
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associated KSP sugar :
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- PAW UI controls
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- Value and symmetry events
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- Automatic persistence on the Part/PartModule hosting the BaseFieldList
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The whole thing seems actually designed with such a scenario in mind, but for some reason some BaseField and BaseFieldList
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methods are using the BaseFieldList.host instance instead of the BaseField.host instance (as for why BaseFieldList has a
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"host" at all, I've no idea and this seems to be a design oversight). There is little to no consistency in which host
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reference is used, they are even sometimes mixed in the same method. For example, BaseFieldList.Load() uses BaseFieldList.host
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in its main body, then calls BaseFieldList.SetOriginalValue() which is relying on BaseField.host.
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Changing every place where a `host` reference is acquired to ensure the BaseField.host reference is used allow to use a custom
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host instance, and shouldn't result in any behavior change. This being said, the stock code can theoretically allow a plugin
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to instantiate a custom BaseField with a null host and have it kinda functional if that field is only used to SetValue() /
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Getvalue() and as long as the field isn't persistent and doesn't have any associated UI_Control. This feels like an extremly
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improbable scenario, so this is probably fine.
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*/
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namespace KSPCommunityFixes.Modding
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{
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[PatchPriority(Order = 0)]
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class BaseFieldListUseFieldHost : BasePatch
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{
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private static AccessTools.FieldRef<object, Callback<object>> BaseField_OnValueModified_FieldRef;
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protected override Version VersionMin => new Version(1, 12, 3);
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protected override void ApplyPatches()
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{
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BaseField_OnValueModified_FieldRef = AccessTools.FieldRefAccess<Callback<object>>(typeof(BaseField<KSPField>), nameof(BaseField<KSPField>.OnValueModified));
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if (BaseField_OnValueModified_FieldRef == null)
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throw new MissingFieldException($"BaseFieldListUseFieldHost patch could not find the BaseField.OnValueModified event backing field");
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// Note : fortunately, we don't need to patch the generic BaseField.GetValue<T>(object host) method because it calls
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// the non-generic GetValue method
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AddPatch(PatchType.Override, AccessTools.FirstMethod(typeof(BaseField<KSPField>), (m) => m.Name == nameof(BaseField<KSPField>.GetValue) && !m.IsGenericMethod), nameof(BaseField_GetValue_Override));
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AddPatch(PatchType.Override, typeof(BaseField<KSPField>), nameof(BaseField<KSPField>.SetValue), nameof(BaseField_SetValue_Override));
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// BaseField.Read() is a public method called from :
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// - BaseFieldList.Load()
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// - BaseFieldList.ReadValue() (2 overloads)
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// The method is really tiny so there is a potential inlining risk (doesn't happen in my tests, but this stuff can be platform
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// dependent). It's only really critical to have BaseFieldList.Load() being patched, the ReadValue() methods are unused in the
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// stock codebase, and it is doubtfull anybody would ever call them.
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AddPatch(PatchType.Override, typeof(BaseField), nameof(BaseField.Read));
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// We also patch BaseFieldList.Load() because :
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// - Of the above mentioned inlining risk
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// - Because it pass the (arguably wrong) host reference to the UI_Control.Load() method, and even though none
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// of the various overloads make use of that argument we might want to be consistent.
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AddPatch(PatchType.Override, typeof(BaseFieldList), nameof(BaseFieldList.Load));
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}
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static object BaseField_GetValue_Override(BaseField<KSPField> instance, object host)
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{
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try
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{
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// In case the field host is null, use the parameter
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if (ReferenceEquals(instance._host, null))
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return instance._fieldInfo.GetValue(host);
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// Uses the field host reference instead of the reference passed as a parameter
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return instance._fieldInfo.GetValue(instance._host);
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}
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catch
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{
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PDebug.Error("Value could not be retrieved from field '" + instance._name + "'");
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return null;
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}
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}
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static bool BaseField_SetValue_Override(BaseField<KSPField> instance, object newValue, object host)
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{
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try
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{
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// In case the field host is null, use the parameter
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if (ReferenceEquals(instance._host, null))
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instance._fieldInfo.SetValue(host, newValue);
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// Uses the field host reference instead of the reference passed as a parameter
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instance._fieldInfo.SetValue(instance._host, newValue);
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// Note : since BaseField.OnValueModified is a "field-like event", it is relying on a compiler-generated
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// private backing field, and the public event "synctatic suger" member can only be invoked from the declaring
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// class, so we can't directly call "__instance.OnValueModified()" here. Additionally, the compiler has the extremly
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// bad taste to name the backing field "OnValueModified" too, resulting in an "ambiguous reference" if we try to use
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// it through the publicized assembly. So we have to resort to creating a FieldRef open delegate for that backing field.
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BaseField_OnValueModified_FieldRef(instance).Invoke(newValue);
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return true;
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}
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catch (Exception ex)
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{
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PDebug.Error(string.Concat("Value '", newValue, "' could not be set to field '", instance._name, "'"));
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PDebug.Error(ex.Message + "\n" + ex.StackTrace + "\n" + ex.Data);
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return false;
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}
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}
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static void BaseField_Read_Override(BaseField instance, string value, object host)
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{
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if (ReferenceEquals(instance._host, null))
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BaseField.ReadPvt(instance._fieldInfo, value, host);
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BaseField.ReadPvt(instance._fieldInfo, value, instance._host);
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}
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static void BaseFieldList_Load_Override(BaseFieldList instance, ConfigNode node)
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{
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for (int i = 0; i < node.values.Count; i++)
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{
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ConfigNode.Value value = node.values[i];
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BaseField baseField = instance[value.name];
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if (baseField == null || baseField.hasInterface || baseField.uiControlOnly)
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continue;
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object host = ReferenceEquals(baseField._host, null) ? instance.host : baseField._host;
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// The original code calls BaseField.Read() here. We bypass it to avoid
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// any inlining risk and call directly the underlying static method.
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BaseField.ReadPvt(baseField._fieldInfo, value.value, host);
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if (baseField.uiControlFlight.GetType() != typeof(UI_Label))
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{
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ConfigNode controlNode = node.GetNode(value.name + "_UIFlight");
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if (controlNode != null)
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baseField.uiControlFlight.Load(controlNode, host);
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}
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else if (baseField.uiControlEditor.GetType() != typeof(UI_Label))
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{
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ConfigNode controlNode = node.GetNode(value.name + "_UIEditor");
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if (controlNode != null)
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baseField.uiControlEditor.Load(controlNode, host);
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}
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}
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for (int j = 0; j < node.nodes.Count; j++)
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{
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ConfigNode configNode = node.nodes[j];
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BaseField baseField = instance[configNode.name];
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if (baseField == null || !baseField.hasInterface || baseField.uiControlOnly)
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continue;
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object host = ReferenceEquals(baseField._host, null) ? instance.host : baseField._host;
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object value = baseField.GetValue(host);
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if (value == null)
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continue;
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(value as IConfigNode)?.Load(configNode);
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if (baseField.uiControlFlight.GetType() != typeof(UI_Label))
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{
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ConfigNode controlNode = node.GetNode(configNode.name + "_UIFlight");
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if (controlNode != null)
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baseField.uiControlFlight.Load(controlNode, host);
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}
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else if (baseField.uiControlEditor.GetType() != typeof(UI_Label))
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{
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ConfigNode controlNode = node.GetNode(configNode.name + "_UIEditor");
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if (controlNode != null)
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baseField.uiControlEditor.Load(controlNode, host);
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}
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}
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instance.SetOriginalValue();
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}
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}
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}

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