digitalmars.D.learn - Cast to original type each argument in template pack
Hello, I have a function:string format(string pattern, T...)(T value) { auto writer = appender!string(); writer.formattedWrite!pattern(convertToUnderlyingType(value)); //Tuple!T(value).expand.to!(OriginalType!T) return writer.data; }The "value" in this function can be any type including "enum". And if it is a "enum" I want to print it's contents not name. So what I need - check if current argument in template pack is enum then convert it in original type. If current argument isn't enum - leave it as is. In my example I showed it with imaginary function "convertToUnderlyingType". How to implement it in D?
Aug 21 2018
On Tuesday, 21 August 2018 at 08:08:58 UTC, Andrey wrote:Hello, I have a function:Do you mean something like this: ´´´ import std.stdio; import std.traits; import std.range; import std.format; import std.meta; enum E { A = "a", B = "b" } void main() { format!"%s"("kuku").writeln; format!"%s"(E.A).writeln; format!"%s %s"("kuku", E.A).writeln; } string format(string pattern, T...)(T vals) { auto writer = appender!string(); writer.formattedWrite!pattern(convertToUnderlyingType!(vals)); //Tuple!T(value).expand.to!(OriginalType!T) return writer.data; } template convertToUnderlyingType(T...) { alias convertToUnderlyingType = staticMap!(convertToUnderlyingTypeSingle, T); } auto convertToUnderlyingTypeSingle(alias value)() { static if(is(typeof(value) == enum)) { return cast(OriginalType!(typeof(value)))value; } else { return value; } } ´´´string format(string pattern, T...)(T value) { auto writer = appender!string(); writer.formattedWrite!pattern(convertToUnderlyingType(value)); //Tuple!T(value).expand.to!(OriginalType!T) return writer.data; }The "value" in this function can be any type including "enum". And if it is a "enum" I want to print it's contents not name. So what I need - check if current argument in template pack is enum then convert it in original type. If current argument isn't enum - leave it as is. In my example I showed it with imaginary function "convertToUnderlyingType". How to implement it in D?
Aug 21 2018