To a degree, but templates and constexpr don't support a bunch of features like compile-time field enumeration and introspection + code generation.
For example, let's say I have a bunch of structs:
struct GeoCoordinate {
int lat, long;
};
struct GeoArea {
std::vector<GeoCoordinate> perimeter;
};
struct Place {
std::string name;
std::string contact_number;
GeoArea area;
};
Now I need to serialize these structs into a format to be sent over the wire. Currently, I have a few choices:
1. Use an off-the-shelf library like protobuf (disclaimer: I work for Google). Then I have to convert my code to a protobuf definition and rely on its code generator to perform [de]serialization. I also have to hope that my library supports all the field definitions I need.
2. Write macros to define each field in each structure. These macros perform some arcane magicks that somehow create the necessary [de]serialization functions. These macros are difficult to write and maintain (or I find a library).
3. Manually define the methods myself. This is tedious, hard to maintain, and error prone.
What if I could write some code in C++ which could read the structure and generate the appropriate serialization code? Something like (syntax hypothetical):
Serializable(Class) {
std::string serialize() {
std::string output;
for (auto member : Class.members()) { // loop unrolled at compile time
if (member.type == int) {
output.append(std::format("{:10}"), member.get())
} else if (member.type == std::string) {
...
} else if (member.type == std::vector) {
...
} else if (std::has_metaclass_v<member.type, Serializable>) {
output.append(member.get().serialize());
}
}
};
};
Then I could annotate my classes with Serializable instead.
Yeah static structural reflection is an important use-case. The main objection I’ve heard to standardization in C++ has to do with maintaining the mistake of conflating structs and classes and supporting C’s long broken unit type.
For example, let's say I have a bunch of structs:
Now I need to serialize these structs into a format to be sent over the wire. Currently, I have a few choices:1. Use an off-the-shelf library like protobuf (disclaimer: I work for Google). Then I have to convert my code to a protobuf definition and rely on its code generator to perform [de]serialization. I also have to hope that my library supports all the field definitions I need.
2. Write macros to define each field in each structure. These macros perform some arcane magicks that somehow create the necessary [de]serialization functions. These macros are difficult to write and maintain (or I find a library).
3. Manually define the methods myself. This is tedious, hard to maintain, and error prone.
What if I could write some code in C++ which could read the structure and generate the appropriate serialization code? Something like (syntax hypothetical):
Then I could annotate my classes with Serializable instead.See https://www.youtube.com/watch?v=4AfRAVcThyA.