STYLE: Replace declare-then-Fill(N) with ::Filled(N) factory method by hjmjohnson · Pull Request #6010 · InsightSoftwareConsortium/ITK

hjmjohnson · 2026-04-03T16:12:39Z

Summary

Replaces the verbose two-line FixedArray initialization pattern with the modern single-line static factory method ::Filled(v).

Before:

ImageType::SizeType size;
size.Fill(16);

After:

constexpr auto size = ImageType::SizeType::Filled(16);

Rules applied

constexpr auto used when the variable is never subsequently modified (test files with concrete types)
auto (without constexpr) used for accumulator variables in loop bodies (.hxx template implementations)
Skipped: cases where Fill() is immediately followed by element-wise overrides (size[0] = w), or where typename disambiguation in deeply nested template parameter scopes makes the replacement non-trivial

Files changed

File	Pattern
`Modules/IO/NRRD/test/itkNrrdLocaleTest.cxx`	`SizeType` + `IndexType` → `constexpr auto`
`Modules/Video/BridgeOpenCV/test/itkOpenCVVideoIOTest.cxx`	`PointType` → `constexpr auto`
`Modules/Filtering/Path/include/itkChainCodeToFourierSeriesPathFilter.hxx`	`VectorType` accumulators → `auto`
`Modules/Filtering/QuadEdgeMeshFiltering/include/itkSmoothingQuadEdgeMeshFilter.hxx`	`VectorType` accumulator → `auto`

Pure style change — no semantic changes.

Suggested by @N-Dekker in #6003 (comment)

greptile-apps · 2026-04-03T16:14:22Z

Greptile Summary

This PR applies a consistent style modernization across 52 files, replacing the two-line T var; var.Fill(N) initialization pattern with either auto var = itk::MakeFilled<T>(N) for non-zero fills or T var{} for zero fills. All replacements are semantically equivalent — itk::MakeFilled is the correct ITK factory for non-zero construction, and {} value-initialization of FixedArray correctly zeroes its underlying C-array data member because FixedArray's default constructor is = default, causing value-init to zero every element.

Confidence Score: 5/5

Pure style change — all replacements are semantically equivalent and safe to merge

All 52 files apply only mechanical, semantics-preserving substitutions. {} on FixedArray correctly zero-initializes via value-init of its C-array member, and itk::MakeFilled is the intended ITK API for filled construction. No logic paths, data flows, or interfaces are altered.

No files require special attention

Important Files Changed

Filename	Overview
Modules/Core/ImageFunction/include/itkGaussianInterpolateImageFunction.hxx	Replaces three Fill(0.0) calls with {} value-initialization on FixedArray accumulators — semantically equivalent since FixedArray's defaulted constructor value-initializes its C-array to zero
Modules/Registration/Common/include/itkLandmarkBasedTransformInitializer.hxx	Replaces Fill(0.0) with {} on VectorType accumulators at three sites — correct zero-initialization
Modules/Filtering/Path/include/itkFourierSeriesPath.hxx	Replaces output.Fill(0) with output{} in Evaluate and EvaluateDerivative — correct zero-initialization of path outputs
Modules/Filtering/Path/include/itkChainCodeToFourierSeriesPathFilter.hxx	Replaces Fill(0.0) with {} on cosCoefficient/sinCoefficient VectorType accumulators inside the harmonic loop
Modules/Filtering/QuadEdgeMeshFiltering/include/itkSmoothingQuadEdgeMeshFilter.hxx	Replaces Fill(0) with {} on VectorType accumulator in GenerateData
Modules/Segmentation/KLMRegionGrowing/include/itkKLMRegionGrowImageFilter.hxx	Replaces Fill(0) with {} on index accumulators inside InitializeKLM loop — correct zero-initialization
Modules/Video/Core/include/itkVideoStream.h	Replaces start.Fill(0) with start{} in header example code
Modules/Core/Common/test/itkBSplineInterpolationWeightFunctionTest.cxx	Replaces ContinuousIndexType declare+Fill(4.15) with itk::MakeFilled
Modules/Filtering/ImageGrid/test/itkBSplineControlPointImageFunctionTest.cxx	Mixed: size/spacing use MakeFilled, index/origin use {}; subsequent .Fill() calls on the same mutable auto variables at lines 53-65 remain valid
Modules/Filtering/ImageGrid/test/itkBSplineScatteredDataPointSetToImageFilterTest3.cxx	Consolidates size declaration to itk::MakeFilled with the computed value inline
Modules/Registration/RegistrationMethodsv4/test/itkTimeVaryingBSplineVelocityFieldPointSetRegistrationTest.cxx	Replaces multiple declare+Fill patterns for domain/velocity field parameters with MakeFilled and {} initialization
Modules/Registration/Common/test/itkMultiResolutionPyramidImageFilterTest.cxx	Replaces Vector declare+Fill with itk::MakeFilled using the computed shift value inline

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["T var (uninitialized)"] --> B["var.Fill(N) — explicit init"]
    C["auto var = itk::MakeFilled&lt;T&gt;(N)"] --> D["var initialized to N at construction"]
    E["T var{}"] --> F["var zero-initialized at construction"]
    A -. "replaced by (non-zero N)" .-> C
    A -. "replaced by (zero N)" .-> E
    B -. removed .-> C
    B -. removed .-> E
    style A fill:#f9f,stroke:#333
    style B fill:#f9f,stroke:#333
    style C fill:#9f9,stroke:#333
    style D fill:#9f9,stroke:#333
    style E fill:#9f9,stroke:#333
    style F fill:#9f9,stroke:#333

_{Reviews (2): Last reviewed commit: "STYLE: Use {}-initialization for zero-fi..." | Re-trigger Greptile}

Modules/Filtering/Path/include/itkChainCodeToFourierSeriesPathFilter.hxx

Modules/IO/NRRD/test/itkNrrdLocaleTest.cxx

dzenanz

Possibly squash commits. Good even as-is.

Using find_declare_then_init.py --pattern fill_nonzero, replaced the two-line pattern: Type var; var.Fill(N); with the single-line form: auto var = itk::MakeFilled<Type>(N); // test files auto var = MakeFilled<Type>(N); // .hxx (already in itk::) across 44 files in Modules/ (excluding Remote/, BridgeOpenCV, BridgeVXL, and itkVectorMeanImageFunction.hxx which uses VariableLengthVector). Follow-up to commit 6cb6bf9 by N-Dekker "STYLE: Replace `T var; var.Fill(x)` with `auto var = MakeFilled<T>(x)`" Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Using find_declare_then_init.py --pattern fill_zero, replaced the two-line pattern: Type var; var.Fill(0); with the single-line value-initialization: Type var{}; {}-initialization zero-initializes all elements for FixedArray and its subclasses (IndexType, SizeType, SpacingType, PointType, VectorType, etc.), which is the canonical C++ idiom for zero-initialization and preserves the correct derived type (unlike ::Filled(0) which returns the base class). Applies to 25 files in Modules/ (excluding Remote/, BridgeOpenCV, BridgeVXL). Follow-up to commit 427df79 by hjmjohnson "STYLE: Use {}-initialization for zero-filled FixedArray-derived types" Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

hjmjohnson · 2026-04-04T16:31:17Z

Thanks @dzenanz I am doing a more complete review and making a more extensive addresing of this style of fix. I'm moving it to a draft until I determine if the a more complete solution can be found.

hjmjohnson · 2026-04-04T19:24:04Z

ARMBUILD-Python failure analysis

The ARMBUILD-Python failure in run 23983133045 is not caused by this PR and is not a disk space issue.

Root cause: clang++: error: unable to execute command: Abort trap: 6 — a SIGABRT during SWIG Python wrapper compilation on the macos-15-arm64 runner.

Evidence:

The crash occurred during the build phase, not testing — 2623 of 2860 tests were "Not Run"
This PR only modifies C++ .hxx headers and test .cxx files — no Python wrapping code is touched
The same ARMBUILD-Python job passes on main (commit b94cca5)
Abort trap: 6 on macOS clang during SWIG compilation is characteristic of an out-of-memory condition — the macos-15-arm64 GitHub runner has 7 GB RAM, and SWIG-generated translation units can exceed this during compilation

Likely cause: Transient OOM on the ARM64 runner due to concurrent memory pressure. A re-run should resolve it.

N-Dekker reviewed Apr 3, 2026

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Modules/Filtering/Path/include/itkChainCodeToFourierSeriesPathFilter.hxx Outdated Show resolved Hide resolved

N-Dekker reviewed Apr 3, 2026

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Modules/IO/NRRD/test/itkNrrdLocaleTest.cxx Outdated Show resolved Hide resolved

hjmjohnson requested a review from N-Dekker April 3, 2026 16:39

dzenanz approved these changes Apr 3, 2026

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hjmjohnson mentioned this pull request Apr 4, 2026

COMP: Free disk space between build and test in Pixi CI #6011

Merged

hjmjohnson and others added 2 commits April 4, 2026 11:28

hjmjohnson marked this pull request as draft April 4, 2026 16:31

hjmjohnson force-pushed the style-sizetype-filled branch from 427df79 to 787267e Compare April 4, 2026 16:42

github-actions bot added area:Core Issues affecting the Core module area:Registration Issues affecting the Registration module area:Segmentation Issues affecting the Segmentation module area:Numerics Issues affecting the Numerics module labels Apr 4, 2026

hjmjohnson marked this pull request as ready for review April 5, 2026 12:53

hjmjohnson merged commit d1b4174 into InsightSoftwareConsortium:main Apr 5, 2026
16 of 22 checks passed

hjmjohnson mentioned this pull request Apr 5, 2026

STYLE: Replace declare-then-assign with const auto for FixedArray-based types #6014

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STYLE: Replace declare-then-Fill(N) with ::Filled(N) factory method#6010

STYLE: Replace declare-then-Fill(N) with ::Filled(N) factory method#6010
hjmjohnson merged 2 commits intoInsightSoftwareConsortium:mainfrom
hjmjohnson:style-sizetype-filled

hjmjohnson commented Apr 3, 2026

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hjmjohnson commented Apr 3, 2026

Summary

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Confidence Score: 5/5

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hjmjohnson commented Apr 4, 2026

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hjmjohnson commented Apr 4, 2026

ARMBUILD-Python failure analysis

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greptile-apps bot commented Apr 3, 2026 •

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