Is this the best way to do a "with" statement in C++?

Answer 1

If you use auto, why use macros at all?

int main()
{
    std::vector<int> vector_with_uncommonly_long_identifier;

    {
        auto& o = vector_with_uncommonly_long_identifier;

        o.push_back(1);
        o.push_back(2);
        o.push_back(3);
    }

    const std::vector<int> constant_duplicate_of_vector_with_uncommonly_long_identifier
        (vector_with_uncommonly_long_identifier);

    {
        const auto& o = constant_duplicate_of_vector_with_uncommonly_long_identifier;

        std::cout
            << o[0] << '\n'
            << o[1] << '\n'
            << o[2] << '\n';
    }

    {
        auto o = constant_duplicate_of_vector_with_uncommonly_long_identifier.size();
        std::cout << o <<'\n';
    }
}

EDIT: Without auto, just use typedef and references.

int main()
{
    typedef std::vector<int> Vec;

    Vec vector_with_uncommonly_long_identifier;

    {
        Vec& o = vector_with_uncommonly_long_identifier;

        o.push_back(1);
        o.push_back(2);
        o.push_back(3);
    }
}

Answer 2

For C++0x (which you're assuming):

int main() {

    std::vector<int> vector_with_uncommonly_long_identifier;

    {
        auto& o = vector_with_uncommonly_long_identifier;

        o.push_back(1);
        o.push_back(2);
        o.push_back(3);

    }
}

Cheers & hth.,

Answer 3

Why not just use a good lambda?

auto func = [&](std::vector<int>& o) {
};
func(vector_with_a_truly_ridiculously_long_identifier);

The simple fact is that if your identifiers are so long, that you can't type them out every time, use a reference, function, pointer, etc to solve this problem, or better, refactor the name. Statements like this (e.g. using() in C#) have additional side effects (deterministic cleanup, in my example). Your statement in C++ has no notable actual benefits, since it doesn't actually invoke any additional behaviour against just writing the code out.

Answer 4

?? attempted vb syntax into C++

with says do all the things in the following block by default referencing the object I've said to do it with right? Executes a series of statements making repeated reference to a single object or structure.

with(a)
 .do
 .domore
 .doitall

so how is the example giving you the same syntax?

to me examples of why to use a with where multiple de referencess

so rather than

book.sheet.table.col(a).row(2).setColour
book.sheet.table.col(a).row(2).setFont
book.sheet.table.col(a).row(2).setText
book.sheet.table.col(a).row(2).setBorder

you have

with( book.sheet.table.col(a).row(2) )
  .setColour
  .setFont
  .setText
  .setBorder

seems just as easy, and more common syntax in C++ to

cell& c = book.sheet.table.col(a).row(2);
c.setColour
c.setFont
c.setText
c.setBorder