[Click] hastable/HashMap

[Marco Wenzel]

Hi Thomas,

thank you very much. As you see, Eddie solved the problem.

Best regards,
Marco.


Paine, Thomas Asa schrieb:
> Marco,
>         What I found was that in hascode.hh there is now defined a hashcode signature for a Template type T, however, it is defined as such...
> 
> template <typename T>
> inline size_t
> hashcode(const T &x)
> {
>     return x.hashcode();
> }
> 
>         As a result the hashcode function is matching the signature of fucntion above.  In your case you are passing in a T* (by reference, not that it really matters)  So I think it we would need something like this to avoid your error...
> 
>         return x->hashcode();
> 
>         But of couse, simply changing this would break non pointer cases.  I'm not sure the best way to work around this though, but I think it explains your error.  I don't *know if you can define both a hashcode(const T &x) and a hashcode(const T* &x).  I suppose you could always define a specific friend function to match your key type, like hashcode(const Packet* &x), but I'm not 100% sure.
> 
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 
>    Thomas Paine {paineta at uwec.edu)}
>    University of Wisconsin - Eau Claire
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> 
> -----Original Message-----
> From: click-bounces at pdos.csail.mit.edu [mailto:click-bounces at pdos.csail.mit.edu] On Behalf Of Marco Wenzel
> Sent: Friday, October 05, 2007 9:56 AM
> To: click at pdos.csail.mit.edu
> Subject: [Click] hastable/HashMap
> 
> Hi,
> 
> since I updated Click to the current git-sources (last version was from
> 2007-07-10), I've got a problem with the usage of HashTable.
> The code
> 
>> dsttable->remove(packet);
> 
> where dsttable is
> 
>> typedef HashMap<Packet*, IPAddress*> DstMap;
>> DstMap* dsttable;
> 
> and packet is a
> 
>> WritablePacket * packet;
> 
> causes thefollowing compile-error:
> 
> ../include/click/hashcode.hh: In function 'size_t hashcode(const T&) [with T =
> Packet*]':
> ../include/click/hashmap.cc:510:   instantiated from 'size_t HashMap<K,
> void*>::bucket(const K&) const [with K = Packet*]'
> ../include/click/hashmap.cc:609:   instantiated from 'bool HashMap<K,
> void*>::remove(const K&) [with K = Packet*]'
> ../elements/local/myelement.cc:49:   instantiated from here
> ../include/click/hashcode.hh:9: error: request for member 'hashcode' in 'x',
> which is of non-class type 'Packet* const'
> 
> It worked correctly before and I don't know how to interpret this error. Sorry,
> if this question is too trivial, but if anyone could help me, I would be very
> glad. Thanks a lot.
> 
> Regards,
> Marco.