Associative array trouble

[Bill Baxter]

You query presence of a key in an AA using 'in'

  if (id in symtab) {
     Symbol sym = symtab[id];
     ...
  } else {
      ..
  }

Or this avoids a double lookup if the symbol is present:

  Symbol* pSym = id in symtab;
  if (pSym !is null) {
         Symbol sym = *pSym;
         ...
  } else {
         ...
  }

--bb

On Fri, Oct 16, 2009 at 1:37 PM, Justin Johansson <no at spam.com> wrote:
> What's wrong with this simple symbol table class?
>
> class Symbol
> {
>   private char[] id;
>   private static Symbol[char[]] symtab;
>
>   private this( string id) {
>      this.id = id;
>   }
>
>   static Symbol opCall( char[] id) {
>      Symbol sym = symtab[id];  // *** ArrayBoundsError here
>
>      if (sym is null) {
>         sym = symtab[id] = new Symbol( id);
>      }
>
>      return sym;
>   }
> }
>
>
> void main() {
>  auto sym = Symbol( "foo");
> }
>
> Running gives Error: ArrayBoundsError
>
> Does symtab need to be initialized in, say, a static if.
> The reference documentation on associative arrays does not suggest that it needs to be.
>
> Thanks for all help.
> Justin
>
>
>