Re: Initialize static members with objects

From:
Victor Bazarov <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Wed, 04 Feb 2009 16:24:08 -0500
Message-ID:
<gmd11p$cl5$1@news.datemas.de>
Johannes Bauer wrote:

Hello group,

I'm changing some code from C-style to STL-C++. In the old code,
something along the lines of this is used:

struct foo {
    int x, y;
};

class moo {
    private:
        const foo[] foos;

That's not a valid C++ declaration (static or no static).

};

and then in a cpp-file:

const foo[] moo::foos = {


That's not a valid C++ declaration.

     { 12, 14 },
    { 99, 3 },
    { 1, 2 },
    { 0 },
};

Now I'd like to change that to

class moo {
    private:
        const std::set<foo> foos;
};

and init that like the above C-style declaration. Is that possible? If
so, how?


I don't think you can init a set. You can, however, init something else
and make it fill the set, like so:

     const std::set<foo> moo::foos;

     int foo_filler(std::set<foo>& set_to_fill)
     {
         foo foos[] = { { 12, 14 }, { 99, 3 }, { 1, 2 }, { 0 } };
         set_to_fill.insert(foos[0]);
         set_to_fill.insert(foos[1]);
         set_to_fill.insert(foos[2]);
         set_to_fill.insert(foos[3]);
     }

     int dummy = foo_filler(moo::foos);

Now, your 'foo' struct does not satisfy the requirement to be
Less-Than-Comparable. It has to have operator< defined for it to be the
element of a std::set. Or you need to provide a predicate for sorting
those structs. Read your favourite C++ book on standard containers.

V
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