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Re^3: Ways to implement a closure

by ikegami (Patriarch)
on Oct 15, 2004 at 19:48 UTC ( [id://399634]=note: print w/replies, xml ) Need Help??


in reply to Re^2: Ways to implement a closure
in thread Ways to implement a closure

I see. Well there you go, yet another way!

Nit: that code works in C (given some imagined Hash class), and the data does stick around:

Hash<...>* demonstration<...>(... a)
   Hash<...>* hash_ptr = new Hash<...>("demo_data", a);
   return new Hash<...>(
      "demonstration_data", hash_ptr
   );
}

[download]

I think you meant this:

sub demonstration {
   my %demonstration_data = ( demo_data => shift );
   return {
      demonstration_data => \%demonstration_data,
   };
}

[download]

Which wouldn't work in C:

Hash<...>* demonstration<...>(... a)
   Hash<...> hash("demo_data", a);
   return new Hash<...>(
      "demonstration_data", \hash    XXX BUG
   );
}

[download]

Replies are listed 'Best First'.
Re^4: Ways to implement a closure
by SpanishInquisition (Pilgrim) on Oct 18, 2004 at 19:50 UTC
    C does not have templates OR classes! (Not that this is a bad thing...)
[reply]
      Oops, I often call C++ by the wrong name. But while the code was C++, the argument does work for C as well. Here's the C version of the C++ snippets: 
      HASH* demonstration(void* p)
   HASH* hash_ptr = hash_new()
   hash_add(hash_ptr, "demo_data", p);

   HASH* outer_hash_ptr = hash_new();
   hash_add(outer_hash_ptr, "demonstration_data", hash_ptr);

   return outer_hash_ptr;
}

      [download]

      and

      HASH* demonstration(void* p)
   HASH hash;
   hash_init(&hash);
   hash_add(&hash, "demo_data", p);

   HASH* outer_hash_ptr = hash_new();
   hash_add(outer_hash_ptr, "demonstration_data", &hash);  XXX BUG

   return outer_hash_ptr;
}

      [download]
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