Avoid unnecessary copies when returning const references from IIFEs.

Also write out the full form of lambdas and the canonical form for (return-by-value) IIFEs to avoid confusion.
libscran · Feb 13, 2025 · bdeff33 · bdeff33
1 parent 07089f8
commit bdeff33
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Showing 4 changed files with 6 additions and 6 deletions.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.14)
 
 project(scran_pca
-    VERSION 0.1.1
+    VERSION 0.1.2
     DESCRIPTION "Principal components analysis for single-cell data"
     LANGUAGES CXX)
 

diff --git a/include/scran_pca/blocked_pca.hpp b/include/scran_pca/blocked_pca.hpp
@@ -670,7 +670,7 @@ class ResidualWrapper {
 
     template<class Right_>
     void multiply(const Right_& rhs, Workspace& work, EigenVector_& output) const {
-        const auto& realized_rhs = [&]() {
+        const auto& realized_rhs = [&]() -> const auto& {
             if constexpr(std::is_same<Right_, EigenVector_>::value) {
                 return rhs;
             } else {

diff --git a/include/scran_pca/simple_pca.hpp b/include/scran_pca/simple_pca.hpp
@@ -87,7 +87,7 @@ void compute_row_means_and_variances(const tatami::Matrix<Value_, Index_>& mat,
             std::vector<Value_> vbuffer(ncells);
 
             for (Index_ r = start, end = start + length; r < end; ++r) {
-                auto results = [&]() {
+                auto results = [&]{
                     if constexpr(sparse_) {
                         auto range = ext->fetch(vbuffer.data(), NULL);
                         return tatami_stats::variances::direct(range.value, range.number, ncells, /* skip_nan = */ false);
@@ -111,7 +111,7 @@ void compute_row_means_and_variances(const tatami::Matrix<Value_, Index_>& mat,
             tatami_stats::LocalOutputBuffer<Scalar> cbuffer(t, start, length, center_v.data());
             tatami_stats::LocalOutputBuffer<Scalar> sbuffer(t, start, length, scale_v.data());
 
-            auto running = [&]() {
+            auto running = [&]{
                 if constexpr(sparse_) {
                     return tatami_stats::variances::RunningSparse<Scalar, Value_, Index_>(length, cbuffer.data(), sbuffer.data(), /* skip_nan = */ false, /* subtract = */ start);
                 } else {

diff --git a/include/scran_pca/utils.hpp b/include/scran_pca/utils.hpp
@@ -95,7 +95,7 @@ class TransposedTatamiWrapper {
 private:
     template<class Right_>
     void inner_multiply(const Right_& rhs, bool transposed, Workspace& work, EigenVector_& out) const {
-        const auto& realized_rhs = [&]() {
+        const auto& realized_rhs = [&]() -> const auto& {
             if constexpr(std::is_same<Right_, EigenVector_>::value) {
                 return rhs;
             } else {
@@ -107,7 +107,7 @@ class TransposedTatamiWrapper {
         auto resultdim = (transposed ? my_ncol : my_nrow);
         auto otherdim = (transposed ? my_nrow : my_ncol);
 
-        tatami::parallelize([&](size_t t, Index_ start, Index_ length) {
+        tatami::parallelize([&](size_t t, Index_ start, Index_ length) -> void {
             auto& vbuffer = work.vbuffers[t];
 
             if (my_prefer_rows != transposed) {