Returning ifstream in a function

Question

Here\'s probably a very noobish question for you: How (if at all possible) can I return an ifstream from a function?

Basically, I need to obtain the filename of a databa

Answer 1

As an option, ifstream may be extended and custom constructor added to new class.

I've extended it to create test resource stream, encapsulating test resource lookup inside of it.

// test_utils.h
class TestResourceStream : public std::ifstream {
    public:
        TestResourceStream(const char* file_path);
};

// test_utils.cpp
namespace fs = std::filesystem;
fs::path test_resource_path(const char* file_path) {
    fs::path path{std::string{"tests/resources/"} + file_path};
    if (!fs::exists(path))
        throw std::runtime_error{std::string{"path "} + 
            fs::absolute(path).c_str() + " does not exist"};
    return path;
}
TestResourceStream::TestResourceStream(const char* file_path)
    :std::ifstream{test_resource_path(file_path).c_str()} {}

// usage in test
TEST_CASE("parse") {
    std::list expertises;
    TestResourceStream stream("requests/page_response.json");
    GosDump::Json::parse(expertises, stream);
    REQUIRE(10 == expertises.size());
}