UFCS for arguments other than first?

[Heisenberg via Digitalmars-d]

What would it take to implement the Uniform Function Call Syntax 
for a function's argument which is not the first?

Right now it is possible to do the following:

> int someNumber(int a, int b)
> {
>     return a + b;
> }
>
> void main()
> {
>     int n1 = 5;
>     int n2 = n1.someNumber(n1 + 1); // Here the `n1` is `a`
> }

But it's not possible to use the `n1' as `b`, for UFCS only 
substitutes the expression before the `.` for the first argument. 
This limits a little bit the flexibility of UFCS. What would it 
take to specify the argument in which UFCS is going to put the 
expression before the `.`? This would make it even more useful.

For instance:

> string someStr = "Yohoho!";
> // To format and print it, one could use `printf':
> writefln("The string is \"%s\".", someStr);
> // But since it is not in the first place,
> // it is not possible to use UFCS for it:
> someStr.writefln("The string is \"%s\"."); // ^ Prints `Yohoho!'
> // One could use tuples to pass
> // the expanded list of strings:
> tuple("The string is \"%s\".", someStr)[].writefln();
> // But it would be much easier if there was
> // some way to tell the compiler
> // to position the argument,
> // for example:
> someStr&1.writefln("The string is \"%s\".");
> //     ^            ^ argument at the position [0]
> //     ^ argument to be put at the position [1]
> // This could even allow to insert the argument
> // at more than one position at once:
> someStr&1&3&4.writefln("Say it, lass!\n" ~
>                        "%s\nI'm a pirate!\n" ~  // someStr goes 
> here (1)
>                        "%s\nHe's a pirate!\n" ~ // not here (2)
>                        "She's a pirate!\n%s" ~  // here (3)
>                        "Ale! Rum! %s\n" ~       // and here (4)
>                        "Wait.. Why is the rum gone?",
>                        "You are a pirate!");    // gets shifted
>                                                 // to position 
> (2)