Re: [Boost-users] Is MultiIndex right for me?

Subject: Re: [Boost-users] Is MultiIndex right for me?
From: Sensei (senseiwa_at_[hidden])
Date: 2013-07-23 04:10:45

On 7/22/13 7:47pm, Daniel James wrote:
> You can use a custom hash function. Here's an example. I made the modulo
> dynamic, but if it's a compile time constant, then the container will be
> a tad bit smaller, and you won't need to pass the hash function and
> equality predicate as parameters.

Thanks Daniel. I have a question, though. Forgive me if I'm being too 
naive, but I'm trying to understand what's going on here! :)

The code you posted seems to be bound at compile time to the integer p 
chosen as modulus (i.e., 53).

How can I, for instance, find all values that are equal modulo 2 now, 
without instantiating another unordered_map? Finding elements modulo p, 
with p given at runtime, is the "something" I'm trying to do here :)

The reason I was looking into MultiIndex is this: decoupling the hashing 
from the actual "equal" predicate.

Thanks for any hints!