static assert

[Tom S]

rm wrote:
> a few questions,
> 1| the doc on the website is not 100% clear for me.
> Is it possible to have an optional const char[] argument in a static assert?
> 2| what am I doing wrong in the code below? Why doesn't the static
> assert fire? (remark that when putting the static assert in a separate
> mixin I can get it to work)
> 
> 
> roel
> 
> ======================================================================
> 
(...)


The problem is that the order of evaluation of statements within a 
template instantiation is not defined. In that case, the recursion was 
evaluating before the static assert. One possible way to solve it:



template itoa(int n)
{
	static if (n<0)
		const char[] itoa = "-" ~ itoa!(-n);
	else static if (n<10)
		const char[] itoa = "0123456789"[n..n+1];
	else
		const char[] itoa = itoa!(n/10) ~ "0123456789"[n%10];
}

template Factor(int n:0)
{
	const int Factor = 1;
}

template next(int i) {
	static assert(i>0, "the optional const char[] argument ;) oh and by the 
way i = " ~ itoa!(i));
	const int next = i-1;
}

template Factor(int n)
{
	pragma(msg, itoa!(n));
	const int Factor = n * Factor!(next!(n));
}


import std.stdio;
void main()
{
	writefln(Factor!(-5));
}



--
Tomasz Stachowiak