This repository was archived by the owner on Feb 26, 2025. It is now read-only.
This repository was archived by the owner on Feb 26, 2025. It is now read-only.
Improve productivity with C++20 concepts? #810
Description
I like the meta-programming feature built into the HighFive library. Thank you!
I am wondering if I can contribute C++20 code to make the compiler error more readable for average users?
For example, I want the compiler to report the missing struct Deflate::apply() function directly, instead of printing 100+ lines to of failed recursive template instantiations.
examples/direct_chunk_write.cpp:98:11: error: no matching member function for call to 'add'
props.add(Deflate{});
~~~~~~^~~
subprojects/highfive/include/highfive/bits/../H5PropertyList.hpp:87:10: note: candidate template ignored: constraints not satisfied [with P = (anonymous namespace)::Jpegls]
void add(const P& property);
^
subprojects/highfive/include/highfive/bits/../H5PropertyList.hpp:86:15: note: because '(anonymous namespace)::Deflate' does not satisfy 'PropertyInterface'
template <PropertyInterface P>
^
subprojects/highfive/include/highfive/bits/../H5PropertyList.hpp:65:9: note: because 'p.apply(hid)' would be invalid: no member named 'apply' in '(anonymous namespace)::Jpegls'
{ p.apply(hid) };Here's the example C++20 concepts code:
diff --git a/include/highfive/H5PropertyList.hpp b/include/highfive/H5PropertyList.hpp
index cc4bf90..c40a848 100644
--- a/include/highfive/H5PropertyList.hpp
+++ b/include/highfive/H5PropertyList.hpp
@@ -57,6 +57,18 @@ class PropertyListBase: public Object {
}
};
+#if __cplusplus >= 202002L
+template<typename P>
+concept PropertyInterface = requires(P p, const hid_t hid)
+{
+ // The struct/class P must contain a public member function that accepts
+ // hid_t as the argument.
+ { p.apply(hid) };
+};
+
+#else
+#define PropertyInterface typename
+#endif
///
/// \brief HDF5 property Lists
@@ -75,7 +87,7 @@ class PropertyList: public PropertyListBase {
/// A property is an object which is expected to have a method with the
/// following signature void apply(hid_t hid) const
///
- template <typename P>
+ template <PropertyInterface P>
void add(const P& property);
///
diff --git a/include/highfive/bits/H5PropertyList_misc.hpp b/include/highfive/bits/H5PropertyList_misc.hpp
index 57fc26d..8ca021f 100644
--- a/include/highfive/bits/H5PropertyList_misc.hpp
+++ b/include/highfive/bits/H5PropertyList_misc.hpp
@@ -71,7 +71,7 @@ inline void PropertyList<T>::_initializeIfNeeded() {
}
template <PropertyType T>
-template <typename P>
+template <PropertyInterface P>
inline void PropertyList<T>::add(const P& property) {