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// written by Don Clugston:
// http://www.digitalmars.com/d/archives/digitalmars/D/announce/4374.html
// http://www.99-bottles-of-beer.net/language-d-1212.html
// Displays the "99 bottles of beer" song at compile time,
// using the template metaprograming facilities of D.
// No executable is generated. No libraries are used.
// Illustrates template default values, template string value parameters,
// compile-time concatenation of constant strings, static if.
module bottles99;
template decimaldigit(int n) {
const string decimaldigit = "0123456789"[n..n+1];
}
template itoa(ulong n)
{
static if ( n < 10L )
const string itoa = decimaldigit!(n);
else
const string itoa = itoa!( n / 10L ) ~ decimaldigit!( n % 10L );
}
template showHowMany(int n, string where, bool needcapital = false)
{
static if ( n > 1 )
const string showHowMany = itoa!(n) ~ " bottles of beer" ~ where ~ "\n";
else static if ( n == 1 )
const string showHowMany = "1 bottle of beer" ~ where ~ "\n";
else static if ( needcapital )
const string showHowMany = "No more bottles of beer" ~ where ~ "\n";
else
const string showHowMany = "no more bottles of beer" ~ where ~ "\n";
}
template beer(int maxbeers, int n = maxbeers)
{
static if ( n > 0 )
const string beer = showHowMany!(n, " on the wall,", true)
~ showHowMany!(n, ".")
~ "Take one down and pass it around, " ~ "\n"
~ showHowMany!( n - 1 , " on the wall.")
~ "\n" ~ beer!(maxbeers, n - 1); // recurse for subsequent verses.
else
const string beer = showHowMany!(n, " on the wall,", true)
~ showHowMany!(n, ".")
~ "Go to the store and buy some more, " ~ "\n"
~ showHowMany!( maxbeers, " on the wall.");
}
pragma(msg, beer!(99));
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