Bug 11279 – Error: no [] operator overload for type Tuple!(int, int, int)

void main(){ import std.typecons; auto a=tuple(0,1,2); a[0]=0;//OK foreach(i;0..3) a[i]=0;//Error: no [] operator overload for type Tuple!(int, int, int)} }

for typetuple, operator[] is a "static" operator: The index *must* be known at compile time, as the return type depends on the parameter. It's actually different overloads for each different index: EG: auto a = tuple('a', 5, 2.2); char c = a[0]; //Calls the first arg int i = a[1]; //Calls the second arg double d = a[2]; //Calls the last arg Because of this putting an operator[] inside a for loop is not possible, as you are basically trying to solve overloads dynamically, which is not possible in a static language like D. What could be a workaround for you is the static foreach construct: void main(){ import std.typecons, std.typetuple; auto a=tuple(0,1,2); a[0]=0;//OK foreach(I;TypeTuple!(0, 1, 2)) a[I]=0;//Error: no [] operator overload for type Tuple!(int, int, int)} } What this does is generate a "type sequence", which contains the "Types" (or in this case, value parameters) 1, 2 and 3. Now, the foreach is statically iterating over the parameters, generating a *unique* body for each loop index. Notice that this time, I used the name "I" this denotes that this argument is actually statically known inside the body of the loop. Closing as invalid.