[Click] element_provides and element_requires

[Nele Gheysens]

Hi,

Thank you for your help. Peter, I am not sure if my problems have 
anything to do with the use of hashmaps, because I used maps before 
without a problem.
Eddie, you asked my which linker errors appeared. But I cannot reproduce 
these linker errors anymore after performing a make distclean. But now I 
have some other problems.  This is my code:

End of file trains_tcb.cc:

#include <click/bighashmap.cc>
#include <click/vector.cc>

CLICK_ENDDECLS
ELEMENT_PROVIDES(sctp_Trains_TCB)
ELEMENT_REQUIRES(sctp_Trains_Timer)
ELEMENT_REQUIRES(sctp_Trains_Link)

End of file trains_CDM.cc:

CLICK_ENDDECLS
ELEMENT_REQUIRES(sctp_Trains_TCB)
ELEMENT_REQUIRES(sctp_Trains_Timer )
ELEMENT_REQUIRES(sctp_Trains_Link)
EXPORT_ELEMENT(Trains_CDM)

When I compile this, I get the following error:

../elements/local/trains/trains_CDM.cc:98: error: 
`get_databuffer_length' undeclared (first use this function)
(and so on for some other functions)
 

where get_databuffer_length()  (and the other functions the compiler is 
complaining about) is a funcion provided bij trains_tcb.cc.
If I put a mistake in de file trains_tcb.cc or trains_tcb.hh, the 
compiler doesn't complain. So I believe that this file isn't compiled. 
But I don't understand why.

Nele


Peter De Cleyn wrote:
> Hi Nele,
>
>
> Im' not sure if you are trying to use map structures in Click 
> elements, but if so I think it is better to use the implementations 
> provided in Click itself. In one of the elements we created, I needed 
> to include the cc (!!) file of the bighashmap at the end in order to 
> get things working and provided the necessary ELEMENT_PROVIDES 
> statements. 
>
> So to be clear: file1.cc and file1.hh define some functionallity 
> (using a map), but do not define an element. element1.cc and 
> element1.hh do define an element and need to use the functionality of 
> file1.
>
> element1.hh includes file1.hh
>
> and 
>
> ---------------------------------------------------
> last lines of file1.cc using bighasmap
> ---------------------------------------------------
>
> #include <click/bighashmap.cc>
>
>
> CLICK_ENDDECLS
>
> ELEMENT_PROVIDES(MIP_BINDING_TABLE)
>
> ELEMENT_REQUIRES(MIP_BINDING);
>
>
> ---------------------------------------------------------------------
> last lines of element1.cc using file1
> ---------------------------------------------------------------------
>
> #include <click/bighashmap.cc>
>
>
> CLICK_ENDDECLS
>
> ELEMENT_REQUIRES(MIP_BINDING_TABLE)
>
> ELEMENT_REQUIRES(MIP_BINDING)
>
> ELEMENT_REQUIRES(MIP_FA_BINDING)
>
> EXPORT_ELEMENT(ForeignAgent)
>
>
> -----------------------------------------------
>
>
> Remark, file1 itselfs requires functionality from a second 
> non-element. So you can generalise the use of the 
> ELEMENT_REQUIRE/ELEMENT_PROVIDE macros, but I added the REQUIRES again 
> in the element file. I don't know if this was necessary, but it works ;-)
>
>
> Hope this is helpful to you,
>
>
> Peter De Cleyn
>
>
> Universiteit Antwerpen
> Departement Wiskunde-Informatica
> Middelheimlaan 1
> 2020 Antwerpen
>
>
> On 7/2/07, *Nele Gheysens* <nele.gheysens at intec.ugent.be 
> <mailto:nele.gheysens at intec.ugent.be>> wrote:
>
>     Hello,
>
>     I tried to apply the following FAQ from the trains website:
>
>     /How can I make Click compile a C++ file that doesn't contain an
>     element?
>     Add an ELEMENT_PROVIDES statement to your .cc file. The Click build
>     process searches for C and C++ files with 'ELEMENT_PROVIDES' as
>     well as
>     'EXPORT_ELEMENT'. You'll have to come up with a one-word tag
>     describing
>     the functionality that your .cc file provides. See the end of
>     'elements/userlevel/fakepcap.cc' for an example; it looks like this:
>     ...
>     CLICK_ENDDECLS
>     ELEMENT_REQUIRES(userlevel|ns)
>     ELEMENT_PROVIDES(FakePcap)
>     Elements that use the 'FakePcap' functionality explicitly require it
>     with ELEMENT_REQUIRES; see 'elements/userlevel/fromdump.cc' for an
>     example./
>
>
>     I followed this example, but I get a whole bunch of linker errors.
>     Does
>     anyone have some experience with this?
>     The files on which I tried this used to be the include and lib map
>     and
>     they didn't cause any problems.
>
>     Thanks,
>
>     Nele Gheysens
>
>     --
>     Nele Gheysens
>     Ghent University - IBCN
>     Department of Information Technology
>     Gaston Crommenlaan 8 bus 201
>     9050 Gent, Belgium
>     E-mail: nele.gheysens at intec.UGent.be
>     <mailto:nele.gheysens at intec.UGent.be>
>     Tel. +32 9 33 14981
>     secr.: +32 (0) 9 33 14900
>     fax :   +32 (0) 9 33 14899
>     WWW: http://www.ibcn.intec.UGent.be
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>
>

-- 
Nele Gheysens
Ghent University - IBCN
Department of Information Technology
Gaston Crommenlaan 8 bus 201
9050 Gent, Belgium
E-mail: nele.gheysens at intec.UGent.be
Tel. +32 9 33 14981
secr.: +32 (0) 9 33 14900
fax :   +32 (0) 9 33 14899
WWW: http://www.ibcn.intec.UGent.be