net/addr/subnet: Simplify using concepts

Change-Id: I013239f07781d18067f612a37f7c40b16609c6d6
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/net/addr/subnet.cpp b/src/net/addr/subnet.cpp
index 47f028f..90fb702 100644
--- a/src/net/addr/subnet.cpp
+++ b/src/net/addr/subnet.cpp
@@ -4,7 +4,10 @@
 
 #include <stdexcept>
 
-namespace stdplus::detail
+namespace stdplus
+{
+
+namespace detail
 {
 
 void invalidSubnetPfx(std::size_t pfx)
@@ -15,13 +18,14 @@
 template class Subnet46<In4Addr, uint8_t>;
 template class Subnet46<In6Addr, uint8_t>;
 
-template Subnet4 SubnetFromStr<Subnet4>::operator()(std::string_view) const;
-template Subnet6 SubnetFromStr<Subnet6>::operator()(std::string_view) const;
-template SubnetAny SubnetFromStr<SubnetAny>::operator()(std::string_view) const;
+} // namespace detail
 
-template char* SubnetToStr<Subnet4>::operator()(char*, Subnet4) const noexcept;
-template char* SubnetToStr<Subnet6>::operator()(char*, Subnet6) const noexcept;
-template char* SubnetToStr<SubnetAny>::operator()(char*,
-                                                  SubnetAny) const noexcept;
+template Subnet4 FromStr<Subnet4>::operator()(std::string_view) const;
+template Subnet6 FromStr<Subnet6>::operator()(std::string_view) const;
+template SubnetAny FromStr<SubnetAny>::operator()(std::string_view) const;
 
-} // namespace stdplus::detail
+template char* ToStr<Subnet4>::operator()(char*, Subnet4) const noexcept;
+template char* ToStr<Subnet6>::operator()(char*, Subnet6) const noexcept;
+template char* ToStr<SubnetAny>::operator()(char*, SubnetAny) const noexcept;
+
+} // namespace stdplus