Re: [Boost-users] Equality comparison of boost::function<>

Subject: Re: [Boost-users] Equality comparison of boost::function<>
From: Christopher Jefferson (chris_at_[hidden])
Date: 2009-08-08 09:16:02

On 8 Aug 2009, at 07:30, Scott McMurray wrote:

> 2009/8/7 Zachary Turner <divisortheory_at_[hidden]>:
>>
>> Out of curiosity, is it impossible due to technical limitations, or  
>> is
>> it just not implemented because it's either difficult or nobody's  
>> ever
>> gotten around to it?
>>
>
> Undecidable by reduction to the halting problem in general, though
> apparently possible for straight-line code (no loops/recursion)
> through the brute-force method of generate all paths and send them to
> a theorem prover to prove equivalence.

That sounds very unnecessary. Surely it would be sufficient, and what  
most people would expect, to check if the two function objects point  
to the same function (in the sense of location in memory), as opposed  
to logically equivalent functions?

I wrote some code that compares instances of the SAT problem, of  
course I didn't do the NP-hard job of checking if they had the same  
set of solutions, just if they were actually the same problem.

Chris