• Sam Hu (15/15) Apr 29 2009 Hello everybody!
• Daniel Keep (10/31) Apr 29 2009 No need to be so formal. Also keep in mind that "sir" only applies to
• Sam Hu (6/6) Apr 29 2009 Thank you very much Daniel!
• bearophile (4/7) Apr 30 2009 For the original poster: this is true in D2+ only, not in D1.

Sam Hu <samhudotsamhu gmail.com> writes:

Hello everybody!

Convert integral value to string literal:

template myToString(ulong n,
      string suffix=n>uint.max?"UL":"U"
{
     static if (n<10)
        enum myToString=cast(char)(n+'0')-suffix; //q1
    else
        enum myToString=.myToString!(n/10,"")-  
              .myToString!(n%10,"")-suffix;            //q2

Here is my questions,sir:
q1.what the key word enum here is doing? not key word char[] or 'string' or
something else?
q2. How does this works?Say n=12,then how can the result be "12"?

Thanks and best regards,
Sam

Daniel Keep <daniel.keep.lists gmail.com> writes:

Sam Hu wrote:
 Hello everybody!
 
 Convert integral value to string literal:
 
 template myToString(ulong n,
       string suffix=n>uint.max?"UL":"U"
 {
      static if (n<10)
         enum myToString=cast(char)(n+'0')-suffix; //q1
     else
         enum myToString=.myToString!(n/10,"")-  
               .myToString!(n%10,"")-suffix;            //q2
 
 Here is my questions,sir:

No need to be so formal.  Also keep in mind that "sir" only applies to
men, and is thus excluding any women in this NG.  :P

 q1.what the key word enum here is doing? not key word char[] or 'string' or
something else?

enum defines a "manifest constant."  In other words, it defines a
constant that does NOT consume any storage anywhere in the program: it
exists only at compile-time.

 enum blah = 42; // single manifest constant

 enum { blah = 42 } // again, but in a block, potentially with others

 enum Stuff { blah = 42 } // again, but in a named enumeration

 q2. How does this works?Say n=12,then how can the result be "12"?

Recursion.  I assume you have modified the code from its original since
'-' would be invalid.  It should be '~' which is the concatenation
operator in D.

 Thanks and best regards,
 Sam

  -- Daniel

Sam Hu <samhudotsamhu gmail.com> writes:

Thank you very much Daniel!
For q1:clear;
For q2: You are right,it should be "~" other than "-" since it is not very
clear from the vidio of Walter's metaprogramming In D:
http://www.vimeo.com/4333802

Thanks again.
Sam

bearophile <bearophileHUGS lycos.com> writes:

Daniel Keep:
 enum defines a "manifest constant."  In other words, it defines a
 constant that does NOT consume any storage anywhere in the program: it
 exists only at compile-time.

For the original poster: this is true in D2+ only, not in D1.

Bye,
bearophile