Refactor PdmValueFieldSpecialization: fix isEqual inconsistency and consolidate redundant base classes

[magnesj]

Description

Replace the PdmValueFieldSpecialization<T> policy class pattern with ADL-based free functions (pdmToVariant / pdmFromVariant / pdmVariantEqual). This removes the centralized cafInternal* specialization header and allows each type to declare its own serialization next to its own declaration. It also eliminates the two redundant base classes and fixes the incorrect isEqual implementations inherited from PdmValueFieldSpecializationDefaults.

ADL design

// Default implementations — work for any Qt-metatype-registered type
namespace caf {
    template <typename T>
    QVariant pdmToVariant( const T& value ) { return QVariant::fromValue( value ); }

    template <typename T>
    void pdmFromVariant( const QVariant& v, T& out ) { out = v.value<T>(); }

    template <typename T>
    bool pdmVariantEqual( const QVariant& a, const QVariant& b ) { return a.value<T>() == b.value<T>(); }
}

Each type provides overloads in its own header. PdmDataValueField and PdmProxyValueField call these via using caf::pdmToVariant to enable ADL. pdmVariantEqual uses if constexpr to handle containers, PdmPointer, and AppEnum, with full specializations for FilePath, float, double, and cvf types.

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Steps

• Add cafPdmFieldTraits.h with default pdmToVariant / pdmFromVariant / pdmVariantEqual — commit 1ecc456
• Add overloads for AppEnum<T> in cafPdmFieldTraits.h — commit 1ecc456
• Add overloads for FilePath in cafPdmFieldTraits.h — commit 1ecc456
• Add overloads for std::vector<T> (delegating element-wise to pdmVariantEqual) — commit 1ecc456
• Add overloads for std::pair<T,U> — commit 1ecc456
• Add overloads for PdmPointer<T> — commit 1ecc456
• Add overloads for float and double (pdmVariantEqual with epsilon) — commit 1ecc456
• Add overloads for cvf::Vec3d, cvf::Mat4d, cvf::Color3f, cvf::Mat3d in their respective cafPdmCvf headers — commit 77e5b03
• Switch PdmDataValueField and PdmProxyValueField to call the free functions — commit f02fbee
• Switch UI framework (cafInternalPdmFieldTypeSpecializations.h, cafInternalPdmUiFieldCapability.inl) to call free functions — commit 411b98f
• Update all remaining call sites (unit tests, application code, UI editors) — commits 77e5b03, f02fbee, 1ffbc4b
• Remove cafInternalPdmValueFieldSpecializations.h and update CMakeLists.txt — commit 1ffbc4b

Files affected

• Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmFieldTraits.h (new)
• Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafInternalPdmValueFieldSpecializations.h (deleted)
• Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmDataValueField.h
• Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmProxyValueField.h
• Fwk/AppFwk/cafProjectDataModel/cafPdmUiCore/cafInternalPdmFieldTypeSpecializations.h
• Fwk/AppFwk/cafProjectDataModel/cafPdmUiCore/cafInternalPdmUiFieldCapability.inl
• Fwk/AppFwk/cafPdmCvf/cafPdmCoreVec3d.h
• Fwk/AppFwk/cafPdmCvf/cafPdmCoreMat4d.h
• Fwk/AppFwk/cafPdmCvf/cafPdmCoreColor3f.h
• Fwk/AppFwk/cafPdmCvf/cafPdmMat3d/cafPdmCoreMat3d.h

[magnesj]

Final design — ADL free functions

flowchart TD
    A["cafPdmFieldTraits.h\nDefaults + std::vector / std::pair / PdmPointer\nAppEnum / FilePath / float / double\npdmVariantEqual with if constexpr"]

    subgraph "Per-type overloads (in their own headers)"
        B1["cafPdmCoreVec3d.h\npdmToVariant / pdmFromVariant\npdmVariantEqual<Vec3d> (string cmp)"]
        B2["cafPdmCoreMat4d.h\npdmToVariant / pdmFromVariant\npdmVariantEqual<Mat4d> (string cmp)"]
        B3["cafPdmCoreColor3f.h\npdmToVariant / pdmFromVariant\npdmVariantEqual<Color3f> (QColor cmp)"]
        B4["cafPdmCoreMat3d.h\npdmToVariant / pdmFromVariant\npdmVariantEqual<Mat3d> (string cmp)"]
    end

    subgraph "Consumers"
        C1["PdmDataValueField / PdmProxyValueField\ntoQVariant / setFromQVariant"]
        C2["PdmUiFieldSpecializationForValueSpec\nconvert / setFromVariant / isDataElementEqual"]
        C3["PdmFieldUiCap::isQVariantDataEqual"]
    end

    A --> C1
    A --> C2
    A --> C3
    B1 --> C1
    B2 --> C1
    B3 --> C1
    B4 --> C1

Loading

cafInternalPdmValueFieldSpecializations.h has been deleted. All serialization customization points now live next to their types or in cafPdmFieldTraits.h for generic types.

[magnesj]

Session notes — 2026-04-02

What was explored

• Read cafPdmValueField.h, cafPdmDataValueField.h, cafPdmProxyValueField.h, cafPdmPtrField.h, and cafInternalPdmValueFieldSpecializations.h in full.
• Mapped the complete PdmValueField inheritance hierarchy.

Key findings

• The isEqual bug is the most important correctness issue: AppEnum, std::vector, and std::pair all use QVariant == QVariant for change detection, which Qt itself documents as unreliable for custom types.
• PdmValueFieldSpecializationStdConversion is entirely dead weight — its two methods are byte-for-byte identical to the primary template.
• PdmField<T> is a macro alias for PdmDataValueField<T> (defined via #define PdmDataValueField PdmField in cafPdmField.h) — not a separate class.
• PdmProxyFieldHandle is an abstract non-templated base sitting between PdmValueField and PdmProxyValueField<T>, used to detect proxy fields without knowing the template parameter.

Open questions

• Is there a known place in ResInsight where the incorrect std::vector isEqual causes a visible bug (e.g. a field editor not refreshing when a vector field changes)?
• Phase 2 (ADL redesign) is a larger refactor — should it be a separate issue/branch from Phase 1?

[magnesj]

Commits

SHA	Description	Date
1ecc456	Add cafPdmFieldTraits.h with ADL-based pdmToVariant/pdmFromVariant/pdmVariantEqual	2026-04-02
77e5b03	Migrate cafPdmCvf types and call sites to free functions	2026-04-02
f02fbee	Switch PdmDataValueField, PdmProxyValueField, and UI editors to free functions	2026-04-02
411b98f	Update UI framework to use free functions	2026-04-02
1ffbc4b	Remove cafInternalPdmValueFieldSpecializations.h and update remaining call sites	2026-04-02

Branch: investigate-field-concept

[magnesj]

Session notes — 2026-04-02 (implementation)

What was implemented

The full ADL-based redesign was completed in 5 incremental commits. All steps in the plan are done.

Key implementation decisions

pdmVariantEqual uses if constexpr rather than overloads. Function templates cannot be partially specialized in C++, so pdmVariantEqual<std::vector<T>> can't be expressed as an overload. The if constexpr chain handles PdmPointer<T>, std::vector<T>, std::pair<T,U>, and AppEnum<T>. Full specializations handle float, double, FilePath, and each cvf type.

All overloads placed in caf:: namespace. cvf types (Vec3d, Mat4d, etc.) live in cvf:: namespace but their serialization overloads are defined in caf:: namespace inside the cafPdmCvf headers. Callers use using caf::pdmToVariant; before calling to bring all caf:: overloads into scope for unqualified lookup.

PdmUiFieldSpecializationForValueSpec<T> updated to delegate to free functions. This was the bridge between PdmUiFieldSpecialization and PdmValueFieldSpecialization. It now delegates to the free functions directly, so all UI field specializations for std::vector, std::pair, std::optional, etc. benefit automatically.

Files deleted

• cafInternalPdmValueFieldSpecializations.h — fully removed, zero remaining references

No remaining open questions

All items from the plan are complete. The investigate-field-concept branch is ready for review.