std::format seems like a great idea.

Used it in one place.  Better than printf
derived functionality.

But they never bothered to think through supporting user types,
and that is a complete mess that is grossly inconsistent or simply
not working from one compiler to the next.

src/ILog.cpp

@@ -46,7 +46,6 @@ MyException::MyException(const char* sz, int i, const char* func__, const char*
 // usage
 //	throw MyException("Expected wallet file not found", __LINE__, __func__, __FILE__);
 	err_number(i) {
-	char buff[20];
-	snprintf(buff, 20, "%d", i);
-	err = std::string(sz) + "\nline " + buff + ", function " + func__ + ", file " + FILE__;
+	err = std::format(R"|({}
+line {}, function {}, file {})|", sz, i, func__, FILE__);
 }

src/db_accessors.h

@@ -36,7 +36,7 @@ namespace ro {
 		sql(std::unique_ptr<Icompiled_sql>&& p) :std::unique_ptr<Icompiled_sql>(p.release()) { }
 		~sql() = default;
 		template <typename T>auto column(int i) const {
-			if constexpr (ro::is_blob_field_type<T>::value) {
+			if constexpr (ro::blob_type<T>) {
 				auto st = (*this)->Isqlite3_column_blob(i);
 				if (st.size_bytes() != sizeof(T)) throw BadDataException();
 				static_assert (std::is_standard_layout<T>(), "not standard layout");

src/mpir_and_base58.h

@@ -57,7 +57,7 @@ namespace ro {
 	bool is_alphanumeric_fixed_length(unsigned int, const char*);
 
 	template <class T> typename std::enable_if<
-		ro::is_blob_field_type<T>::value,
+		ro::blob_type<T>,
 		decltype(T::type_indentifier, uint32_t())
 	>::type fasthash(const T& p_blob) {
 		static_assert(sizeof(T) % 8 == 0, "fasthash assumes a multiple of 8 bytes");
@@ -181,3 +181,4 @@ namespace ro {
 		this->operator char* [this->length] = '\0';
 	}
 }
+

src/ristretto255.h

@@ -138,17 +138,16 @@ namespace ro {
 		static constexpr bool value = is_blob_field_type::template test<T>();
 	};
 
+	template<class T> concept blob_type = ro::is_blob_field_type<T>::value;
+
+
 	//	At present our serial classes consist of std::span<uint8_t> and custom classes that publicly inherit from std::span<byte>
 	//	To handle compound objects, add custom classes inheriting from std::span<byte>[n]
 
 	//	template class that generates a std::span of bytes over the blob
 	//	field of any object containing a blob record, which is normally sufficient
 	//	for a machine independent representation of that object
-	template <typename T>
-	std::enable_if_t<
-		is_blob_field_type<T>::value,
-		std::span<const byte>
-	> serialize(const T& pt) {
+	template <blob_type T>	std::span<const byte> serialize(const T& pt) {
 		return serialize(pt.blob);
 	}
 
@@ -567,7 +566,7 @@ namespace ristretto255 {
 	{
 		//	We will be reading points from the database, as blobs,
 		//	reading them from the network as blobs,
-		//	and reading them from human entered text as base52 encoded blobs.
+		//	and reading them from human entered text as base58 encoded blobs.
 		//	Therefore, invalid point initialization data is all too possible.
 	public:
 		static constexpr unsigned int type_indentifier = 1;
@@ -770,6 +769,7 @@ namespace ristretto255 {
 		}
 	};
 
+	static_assert(ro::blob_type<scalar> && !ro::blob_type<int>);
 	static_assert(ro::is_blob_field_type<scalar>::value);
 	static_assert(ro::is_blob_field_type<scalar&>::value);
 	static_assert(ro::is_blob_field_type<point>::value);