Casting Structs

[Paul D Anderson via Digitalmars-d-learn]

I'm working on the decimal number package for D. A decimal is a 
struct with precision, max exponent and rounding mode parameters: 
"Decimal!(PRECISION, MAX_EXPO, ROUNDING)". I was trying to 
overload the opCast operator for this struct and I found that it 
does not seem necessary. I can cast decimals with different 
precisions, etc., back and forth without overloading opCast.

This code works:
alias dec9  = Decimal!(9,99);
alias dec10 = Decimal!(10,99);

dec9 bingo = dec9("123.45");
dec10 little = cast(dec10(bingo));

assert(little == dec10("123.45"));

Is this expected behavior?

Paul