better solution for template restriction

boostorg · Apr 25, 2024 · 8125277 · 8125277
1 parent 9a7aa5e
commit 8125277
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Showing 2 changed files with 26 additions and 35 deletions.
diff --git a/include/boost/histogram/accumulators/collector.hpp b/include/boost/histogram/accumulators/collector.hpp
@@ -38,21 +38,12 @@ class collector {
   using size_type = typename container_type::size_type;
   using const_pointer = typename container_type::const_pointer;
 
-  template <typename... Args>
+  // make template only match if forwarding args to container is valid
+  template <typename... Args, class = decltype(container_type(std::declval<Args>()...))>
   explicit collector(Args&&... args) : container_(std::forward<Args>(args)...) {}
 
-  // we must explicitly implement the copy/move ctors so that they are a
-  // better match than the generic forwarding template above
-  collector(const collector& other) : container_(other.container_) {}
-  collector(collector& other) : container_(other.container_) {}
-  collector(collector&& other) : container_(std::move(other.container_)) {}
-
-  // when copy/move ctors are explicitly implemented, one also has to implement the
-  // assignment operators
-  collector& operator=(const collector&) = default;
-  collector& operator=(collector&&) = default;
-
-  template <class T, typename... Args>
+  // make template only match if forwarding args to container is valid
+  template <class T, typename... Args, class = decltype(container_type(std::initializer_list<T>(),std::declval<Args>()...))>
   explicit collector(std::initializer_list<T> list, Args&&... args)
       : container_(list, std::forward<Args>(args)...) {}
 

diff --git a/test/utility_clopper_pearson_interval_test.cpp b/test/utility_clopper_pearson_interval_test.cpp
@@ -18,46 +18,46 @@ template <class T>
 void test() {
   const T atol = 0.001;
 
-  clopper_pearson_interval<T> iv(deviation{1});
+  clopper_pearson_interval<T> iv(deviation{1.f});
 
   {
-    const auto x = iv(0, 1);
-    BOOST_TEST_IS_CLOSE(x.first, 0.0, atol);
-    BOOST_TEST_IS_CLOSE(x.second, 0.841, atol);
+    const auto x = iv(0.f, 1.f);
+    BOOST_TEST_IS_CLOSE(x.first, 0.f, atol);
+    BOOST_TEST_IS_CLOSE(x.second, 0.841f, atol);
 
-    fraction<T> f(0, 1);
+    fraction<T> f(0.f, 1.f);
     const auto y = iv(f);
-    BOOST_TEST_IS_CLOSE(y.first, 0.0, atol);
-    BOOST_TEST_IS_CLOSE(y.second, 0.841, atol);
+    BOOST_TEST_IS_CLOSE(y.first, 0.f, atol);
+    BOOST_TEST_IS_CLOSE(y.second, 0.841f, atol);
   }
 
   {
-    const auto x = iv(1, 0);
-    BOOST_TEST_IS_CLOSE(x.first, 0.158, atol);
-    BOOST_TEST_IS_CLOSE(x.second, 1.0, atol);
+    const auto x = iv(1.f, 0.f);
+    BOOST_TEST_IS_CLOSE(x.first, 0.158f, atol);
+    BOOST_TEST_IS_CLOSE(x.second, 1.f, atol);
 
-    fraction<T> f(1, 0);
+    fraction<T> f(1.f, 0.f);
     const auto y = iv(f);
-    BOOST_TEST_IS_CLOSE(y.first, 0.158, atol);
-    BOOST_TEST_IS_CLOSE(y.second, 1.0, atol);
+    BOOST_TEST_IS_CLOSE(y.first, 0.158f, atol);
+    BOOST_TEST_IS_CLOSE(y.second, 1.f, atol);
   }
 
   {
-    const auto x = iv(5, 5);
-    BOOST_TEST_IS_CLOSE(x.first, 0.304, atol);
-    BOOST_TEST_IS_CLOSE(x.second, 0.695, atol);
+    const auto x = iv(5.f, 5.f);
+    BOOST_TEST_IS_CLOSE(x.first, 0.304f, atol);
+    BOOST_TEST_IS_CLOSE(x.second, 0.695f, atol);
   }
 
   {
-    const auto x = iv(1, 9);
-    BOOST_TEST_IS_CLOSE(x.first, 0.017, atol);
-    BOOST_TEST_IS_CLOSE(x.second, 0.294, atol);
+    const auto x = iv(1.f, 9.f);
+    BOOST_TEST_IS_CLOSE(x.first, 0.017f, atol);
+    BOOST_TEST_IS_CLOSE(x.second, 0.294f, atol);
   }
 
   {
-    const auto x = iv(9, 1);
-    BOOST_TEST_IS_CLOSE(x.first, 0.705, atol);
-    BOOST_TEST_IS_CLOSE(x.second, 0.982, atol);
+    const auto x = iv(9.f, 1.f);
+    BOOST_TEST_IS_CLOSE(x.first, 0.705f, atol);
+    BOOST_TEST_IS_CLOSE(x.second, 0.982f, atol);
   }
 }