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any ideas for this one?

--code--
template<>
class ACE_Hash<KeyType>
{
public:
u_long operator() (const KeyType kt) const
{
int val = kt;
return (u_long)val;
}
};
--code--

while "operator u_long (void) const; " may be easily understood as a
conversion operator;
what does "u_long operator() (const KeyType kt) const;" mean?

* thomas:
> any ideas for this one?
>
> --code--
> template<>
> class ACE_Hash<KeyType>
> {
> public:
> u_long operator() (const KeyType kt) const
> {
> int val = kt;
> return (u_long)val;
> }
> };
> --code--
>
> while "operator u_long (void) const; " may be easily understood as a
> conversion operator;
> what does "u_long operator() (const KeyType kt) const;" mean?

'operator()' is the function call operator.

Given


KeyType const key = ...;
ACE_Hash<KeyType> hash;

you can use the hash object as a function

u_long const x = hash( key );

in order to obtain the result of first converting key to int and then
further to u_long, whatever that type is.


Cheers, & hth.,

- Alf

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