Re: [Boost-users] returning pointer to Boost::assign::map_list_of

Subject: Re: [Boost-users] returning pointer to Boost::assign::map_list_of
From: Thorsten Ottosen (nesotto_at_[hidden])
Date: 2010-07-16 08:02:47

alapex0310_at_[hidden] skrev:
> Hi,
> 
> I am new to Boost::Assign.
> 
> I have a std::map<std::string, unsigned char> and I have a SomeClass 
> with constructor SomeClass(std::string, std::map<std::string, unsigned 
> char>*) and I want to pass the pointer to the result of map_list_of to 
> SomeClass like this:
> 
>            SomeClass *psc = new 
> SomeClass("SomeClassName",map_list_of("one",1)("two",2)("three",3)("four",4)("five",5); 
> 
> 
> In the example at 
> http://www.boost.org/doc/libs/1_43_0/libs/assign/doc/index.html#intro , 
> the map_list_of is definitely returning a small map. I don't want to 
> pass the map object itself but the pointer to the map object returned by 
> map_list_of.

map_list_of returns an unspecified type that converts to a map. So you 
have two options:

1. change your argument to map<string,unsigned char>
2. make your constructor a template, and let the "map" argument be
   const T& mapValues instead (I'm assuming you are going to initialize 
a map in the constructor.

2) might be more efficient, if that matters

-Thorsten