[Click] read handler with parameters

[Eddie Kohler]

Functions that take packets should not use the handler methodology.  There is 
no way to pass packet memory into a handler from a user level program, it does 
not make sense.  Use another port on your element, or add another function to 
your element and simply call that function.  See RED for examples.  At most 
you can pass the packet DATA in as a string and use Packet::make() to create a 
packet from that.

Eddie


sam barker wrote:
> Hi Eddie,
> I saw that we can only pass a string to the function.
> 
> Suppose I want to pass pointers as arguments[Packet *].
> Should I convert it into string and then pass it to my function.?
> 
> Cheers ,
> Sam
> 
> On Jan 16, 2008 1:09 PM, sam barker <sam.barker0 at gmail.com 
> <mailto:sam.barker0 at gmail.com>> wrote:
> 
>     Thanks Eddie.
> 
> 
>     On Jan 16, 2008 12:41 PM, Eddie Kohler <kohler at cs.ucla.edu
>     <mailto:kohler at cs.ucla.edu>> wrote:
> 
>         The argument gets passed in as a single string.  You can parse
>         multiple
>         arguments out of it by, for example, separating at spaces, via
>         cp_space_kparse.
> 
>         Eddie
> 
> 
>         sam barker wrote:
>          > Hi Eddie,
>          > Thanks for the tip.I am able to pass a value.
>          >
>          > Is it possible to for me to pass more that one argument
>         through the
>          > set_handler?
>          >
>          > Cheers,
>          > Sam
>          >
>          > On Jan 16, 2008 10:24 AM, Eddie Kohler < kohler at cs.ucla.edu
>         <mailto:kohler at cs.ucla.edu>
>          > <mailto:kohler at cs.ucla.edu <mailto:kohler at cs.ucla.edu>>> wrote:
>          >
>          >     If you want your read handler to take parameters, you
>         need to use
>          >     set_handler() and supply Handler::OP_READ |
>         Handler::READ_PARAM.
>          >
>          >    
>         http://www.read.cs.ucla.edu/click/doxygen/classElement.html#4b0cd1711fb51b8aba0f2e01f3eba9c0
>         <http://www.read.cs.ucla.edu/click/doxygen/classElement.html#4b0cd1711fb51b8aba0f2e01f3eba9c0>
>          >
>          >     Eddie
>          >
>          >
>          >     sam barker wrote:
>          >      > Hi Beyers,
>          >      > I tried it but got the error "read handlers does not take
>          >     parameters".
>          >      >
>          >      > Is there anyway way to call the read handler with
>          >     parameters.[Suppose if you
>          >      > want to return  a value  corresponding to the passed
>         parameter]
>          >      >
>          >      > I was going through a manual called coding concepts
>         which clearly
>          >     states
>          >      > that "You can't call a ReadHandler with arguments"
>          >      >
>          >      >
>          >      > Cheers,
>          >      > Sam
>          >      > On Jan 15, 2008 9:01 PM, Beyers Cronje <
>         bcronje at gmail.com <mailto:bcronje at gmail.com>
>          >     <mailto:bcronje at gmail.com <mailto:bcronje at gmail.com>>> wrote:
>          >      >
>          >      >> Hi Sam,
>          >      >>
>          >      >> I've never passed a parameter to a read handler
>         before, so this
>          >     might be
>          >      >> wrong....
>          >      >>
>          >      >> Your telnet command should be:
>          >      >>
>          >      >> read readelement_name.a_handle 1
>          >      >>
>          >      >> Also I believe the prototype of add_handlers is onle
>         'virtual void
>          >      >> add_handlers();'
>          >      >>
>          >      >> Beyers
>          >      >>
>          >      >> On Jan 15, 2008 4:11 AM, sam barker
>         <sam.barker0 at gmail.com <mailto:sam.barker0 at gmail.com>
>          >     <mailto:sam.barker0 at gmail.com
>         <mailto:sam.barker0 at gmail.com>>> wrote:
>          >      >>
>          >      >>> Hi All,
>          >      >>> I was trying out the read handler with a parameter
>         and I seem
>          >     to be
>          >      >>> stuck.
>          >      >>>
>          >      >>> Basically I wan t to  pass an int parameter to
>         my_func().
>          >      >>>
>          >      >>> After I telnet into the localhost how do I call the
>         function?.
>          >      >>> I had used  read readelement_name.a_handle(1);
>          >      >>>
>          >      >>> The the partial code of my .cc file is below
>          >      >>>
>          >      >>>
>          >      >>> String readelement::handle(Element *e, void *thunk){
>          >      >>>    readelement * me = (readelement *) e;
>          >      >>>
>          >      >>>    int *i;
>          >      >>>    i=(int *)thunk;
>          >      >>>    return me->my_func(i);
>          >      >>> }
>          >      >>> void readelement::add_handlers(void * thunk){
>          >      >>>    add_read_handler("a_handle", &handle, (void
>         *)thunk);
>          >      >>> }
>          >      >>>
>          >      >>> Regards,
>          >      >>> Sam
>          >      >>> _______________________________________________
>          >      >>> click mailing list
>          >      >>> click at amsterdam.lcs.mit.edu
>         <mailto:click at amsterdam.lcs.mit.edu>
>         <mailto:click at amsterdam.lcs.mit.edu
>         <mailto:click at amsterdam.lcs.mit.edu>>
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>          >      >>>
>          >      >>
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