Refactor World, part 1/x

- Create create_world and delete multiple constructor.
- Try "free function" api style.

Author: ahojukka5

.clang-format

@@ -1,20 +1,28 @@
 # SPDX-FileCopyrightText: 2025 VTT Technical Research Centre of Finland Ltd
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-AllowShortIfStatementsOnASingleLine: WithoutElse
-AllowShortLoopsOnASingleLine: true
-# AllowShortFunctionsOnASingleLine: InlineOnly
+# https://clang.llvm.org/docs/ClangFormatStyleOptions.html
+
+# Basic settings
+
 IndentWidth: 2
 TabWidth: 2
 UseTab: Never
-ColumnLimit: 120
-BreakConstructorInitializers: BeforeColon # ensures that : is placed on a new line
-ConstructorInitializerAllOnOneLineOrOnePerLine: true # puts each initializer on its own line
-AllowAllConstructorInitializersOnNextLine: false # disables grouping on the next line
-BinPackParameters: false # prevents squeezing multiple parameters into one line
-AlignAfterOpenBracket: Align # keeps nice vertical alignment
-# ColumnLimit: 120
+ColumnLimit: 100
+
+# Allow things on a single line
+
+AllowShortIfStatementsOnASingleLine: true
+AllowShortLoopsOnASingleLine: true
 AllowShortFunctionsOnASingleLine: All
 AllowShortLambdasOnASingleLine: true
 AllowShortCaseLabelsOnASingleLine: true
-# AllowShortFunctionsOnASingleLine: Inline
+
+# Constructor formatting
+
+# ensures that : is placed on a new line
+BreakConstructorInitializers: BeforeColon
+ConstructorInitializerAllOnOneLineOrOnePerLine: false # puts each initializer on its own line
+AllowAllConstructorInitializersOnNextLine: false # disables grouping on the next line
+BinPackParameters: false # prevents squeezing multiple parameters into one line
+AlignAfterOpenBracket: Align # keeps nice vertical alignment

apps/aluminumNew/Aluminum.hpp

@@ -161,8 +161,8 @@ class Aluminum : public Model {
 
   void prepare_operators(double dt) {
     World w = get_world();
-    auto spacing = w.spacing();
-    auto size = w.size();
+    auto spacing = get_spacing(w);
+    auto size = get_size(w);
     auto dx = spacing[0];
     auto dy = spacing[1];
     auto dz = spacing[2];
@@ -236,9 +236,9 @@ class Aluminum : public Model {
 
     FFT &fft = get_fft();
     World w = get_world();
-    double dx = w.spacing()[0];
-    double x0 = w.origin()[0];
-    int Lx = w.size()[0];
+    double dx = get_spacing(w, 0);
+    double x0 = get_origin(w, 0);
+    int Lx = get_size(w, 0);
     const Decomposition &decomp = get_decomposition();
     std::array<int, 3> low = decomp.get_inbox().low;
     std::array<int, 3> high = decomp.get_inbox().high;

apps/aluminumNew/SeedGridFCC.hpp

@@ -30,7 +30,14 @@ class SeedGridFCC : public FieldModifier {
   SeedGridFCC() = default;
 
   SeedGridFCC(int Ny, int Nz, double X0, double radius, double amplitude, double rho, double rseed)
-      : m_Nx(1), m_Ny(Ny), m_Nz(Nz), m_X0(X0), m_radius(radius), m_amplitude(amplitude), m_rho(rho), m_rseed(rseed) {}
+      : m_Nx(1),
+        m_Ny(Ny),
+        m_Nz(Nz),
+        m_X0(X0),
+        m_radius(radius),
+        m_amplitude(amplitude),
+        m_rho(rho),
+        m_rseed(rseed) {}
 
   // getters
   int get_Nx() const { return m_Nx; }
@@ -65,9 +72,9 @@ class SeedGridFCC : public FieldModifier {
     Vec3<int> high = decomp.get_inbox().high;
 
     // Use the new World API to get size, spacing, and origin
-    auto size = w.size();
-    auto spacing = w.spacing();
-    auto origin = w.origin();
+    auto size = get_size(w);
+    auto spacing = get_spacing(w);
+    auto origin = get_origin(w);
     auto Ly = size[1];
     auto Lz = size[2];
     auto dx = spacing[0];

apps/aluminumNew/aluminumTest.cpp

@@ -44,7 +44,7 @@ using namespace Catch::Matchers;
 TEST_CASE("Aluminum functionality", "[Aluminum]") {
   SECTION("Step model and calculate norm of the result") {
     MPI_Worker worker(0, nullptr);
-    World world({32, 32, 32});
+    World world = create_world({32, 32, 32});
     Decomposition decomp = make_decomposition(world);
     auto plan_options = heffte::default_options<heffte::backend::fftw>();
     FFT fft(decomp, MPI_COMM_WORLD, plan_options, world);

apps/tungsten.cpp

@@ -103,8 +103,8 @@ class Tungsten : public Model {
 
   void prepare_operators(double dt) {
     World w = get_world();
-    auto spacing = w.spacing();
-    auto size = w.size();
+    auto spacing = get_spacing(w);
+    auto size = get_size(w);
     auto dx = spacing[0];
     auto dy = spacing[1];
     auto dz = spacing[2];

examples/01_hello_world.cpp

@@ -35,23 +35,23 @@ int main() {
   std::array<int, 3> dimensions = {10, 20, 30};
   std::array<double, 3> origin = {0.0, 0.0, 0.0};
   std::array<double, 3> discretization = {0.1, 0.1, 0.1};
-  World world(dimensions, origin, discretization);
+  World world = create_world(dimensions, origin, discretization);
 
   // Retrieve world properties
   cout << "World properties:" << endl;
-  auto size = world.size();
+  auto size = get_size(world);
   cout << "Dimensions: " << size[0] << " x " << size[1] << " x " << size[2] << endl;
-  auto world_origin = world.origin();
+  auto world_origin = get_origin(world);
   cout << "Origin: (" << world_origin[0] << ", " << world_origin[1] << ", " << world_origin[2] << ")" << endl;
-  auto spacing = world.spacing();
+  auto spacing = get_spacing(world);
   cout << "Spacing: dx = " << spacing[0] << ", dy = " << spacing[1] << ", dz = " << spacing[2] << endl;
 
   // Simpler way:
   cout << world << endl;
 
   // If just the size of the doman is defined, it is assumed that x0 = y0 = z0 =
   // 0 and dx = dy = dz = 1
-  World world2({64, 64, 64});
+  World world2 = create_world({64, 64, 64});
   cout << world2 << endl;
 
   return 0;

examples/02_domain_decomposition.cpp

@@ -31,15 +31,15 @@ int main(int argc, char *argv[]) {
   // Domain decomposition can be done in a manual manner, just by giving the
   // size of the calculation domain, id number and total number of subdomains:
   int comm_rank = 0, comm_size = 2;
-  World world1({32, 4, 4});
+  World world1 = create_world({32, 4, 4});
   Decomposition decomp1 = make_decomposition(world1, comm_rank, comm_size);
   cout << decomp1 << endl;
 
   // In practice, we let MPI communicator to decide the number of subdomains.
   MPI_Init(&argc, &argv);
   MPI_Comm comm = MPI_COMM_WORLD;
   MPI_Comm_rank(comm, &comm_rank);
-  World world2({32, 4, 4});
+  World world2 = create_world({32, 4, 4});
   Decomposition decomp2 = make_decomposition(world2, comm);
   if (comm_rank == 0) cout << decomp2 << endl;
 

examples/03_parallel_fft.cpp

@@ -112,7 +112,7 @@ int main(int argc, char *argv[]) {
   MPI_Comm_size(comm, &num_procs);
 
   // Construct world, decomposition and fft
-  World world({8, 1, 1});
+  World world = create_world({8, 1, 1});
   Decomposition decomposition = make_decomposition(world, comm);
   auto plan_options = heffte::default_options<heffte::backend::fftw>();
   FFT fft(decomposition, comm, plan_options, world);

examples/04_diffusion_model.cpp

@@ -126,8 +126,8 @@ class Diffusion : public Model {
     for (int k = i_low[2]; k <= i_high[2]; k++) {
       for (int j = i_low[1]; j <= i_high[1]; j++) {
         for (int i = i_low[0]; i <= i_high[0]; i++) {
-          auto origin = w.origin();
-          auto spacing = w.spacing();
+          auto origin = get_origin(w);
+          auto spacing = get_spacing(w);
           double x = origin[0] + i * spacing[0];
           double y = origin[1] + j * spacing[1];
           double z = origin[2] + k * spacing[2];
@@ -144,8 +144,8 @@ class Diffusion : public Model {
     if (rank0) cout << "Prepare operators" << endl;
     idx = 0;
     double pi = std::atan(1.0) * 4.0;
-    auto spacing = w.spacing();
-    auto size = w.size();
+    auto spacing = get_spacing(w);
+    auto size = get_size(w);
     double fx = 2.0 * pi / (spacing[0] * size[0]);
     double fy = 2.0 * pi / (spacing[1] * size[1]);
     double fz = 2.0 * pi / (spacing[2] * size[2]);
@@ -229,7 +229,7 @@ void run() {
   double z0 = -0.5 * Lz * dz;
 
   // Construct world, decomposition, fft and model
-  World world({Lx, Ly, Lz}, {x0, y0, z0}, {dx, dy, dz});
+  World world = create_world({Lx, Ly, Lz}, {x0, y0, z0}, {dx, dy, dz});
   Decomposition decomp = make_decomposition(world);
   auto plan_options = heffte::default_options<heffte::backend::fftw>();
   FFT fft(decomp, MPI_COMM_WORLD, plan_options, world);

examples/05_simulator.cpp

@@ -60,8 +60,8 @@ class GaussianIC : public FieldModifier {
     for (int k = low[2]; k <= high[2]; k++) {
       for (int j = low[1]; j <= high[1]; j++) {
         for (int i = low[0]; i <= high[0]; i++) {
-          auto origin = w.origin();
-          auto spacing = w.spacing();
+          auto origin = get_origin(w);
+          auto spacing = get_spacing(w);
           double x = origin[0] + i * spacing[0];
           double y = origin[1] + j * spacing[1];
           double z = origin[2] + k * spacing[2];
@@ -105,8 +105,8 @@ class Diffusion : public Model {
 
     if (is_rank0()) std::cout << "Prepare operators" << std::endl;
     size_t idx = 0;
-    auto spacing = w.spacing();
-    auto size = w.size();
+    auto spacing = get_spacing(w);
+    auto size = get_size(w);
     double fx = 2.0 * PI / (spacing[0] * size[0]);
     double fy = 2.0 * PI / (spacing[1] * size[1]);
     double fz = 2.0 * PI / (spacing[2] * size[2]);
@@ -181,7 +181,7 @@ void run() {
   std::array<int, 3> dimensions = {L, L, L};
   std::array<double, 3> discretization = {h, h, h};
   std::array<double, 3> origin = {o, o, o};
-  World world(dimensions, origin, discretization);
+  World world = create_world(dimensions, origin, discretization);
 
   Decomposition decomp = make_decomposition(world);
   auto plan_options = heffte::default_options<heffte::backend::fftw>();