Re: [Boost-users] [lambda]Predicate construction

From: Anakreon (anakreonmejdi_at_[hidden])
Date: 2005-09-29 06:39:21

Peter Dimov wrote:
> Anakreon wrote:
> 
> 
>>struct event_locator: public unary_function<bool, Event*> {
>>  int tId;
>>  event_locator(const int tid) : tId(tid) {}
>>  const bool operator() (Event* e) {
>>return e->hasTransaction()
>>  && e->getTransaction().getId() == tId;
>>  }
>>};
> 
> 
> The best (IMO) approach would be to define
> 
> bool has_transaction_with_id( Event /*const?*/ * e, int id )
> {
>     return e->hasTransaction() && e->getTransaction().getId() == id;
> }
> 
I intended to use lambda in order to avoid declaration of functions or structs
for STL algorithms. If I need to declare the function above then I find no
reason to use lambda at all.

> You can use
> 
> bind( &Event::hasTransaction, _1 ) && bind( &Transaction::getId, bind( 
> &Event::getTransaction, _1 ) ) == tid
> 
> but I'm not sure that you'd want to. 
It looks to complex.

Thanks Peter for the response.