Since the beginning of the lockdown I have been working hard on a new object-oriented interface to the online database ODB. I have the code now in an initial state where it is ready for
testing and commenting. The basic idea is that there is an object midas::odb, which represents a value or a sub-tree in the ODB. Reading, writing and watching is done through this
object. To get started, the new API has to be included with
#include <odbxx.hxx>
To create ODB values under a certain sub-directory, you can either create one key at a time like:
midas::odb o;
o.connect("/Test/Settings", true); // this creates /Test/Settings
o.set_auto_create(true); // this turns on auto-creation
o["Int32 Key"] = 1; // create all these keys with different types
o["Double Key"] = 1.23;
o["String Key"] = "Hello";
or you can create a whole sub-tree at once like:
midas::odb o = {
{"Int32 Key", 1},
{"Double Key", 1.23},
{"String Key", "Hello"},
{"Subdir", {
{"Another value", 1.2f}
}
};
o.connect("/Test/Settings");
To read and write to the ODB, just read and write to the odb object
int i = o["Int32 Key];
o["Int32 Key"] = 42;
std::cout << o << std::endl;
This works with basic types, strings, std::array and std::vector. Each read access to this object triggers an underlying read from the ODB, and each write access triggers a write to the
ODB. To watch a value for change in the odb (the old db_watch() function), you can use now c++ lambdas like:
o.watch([](midas::odb &o) {
std::cout << "Value of key \"" + o.get_full_path() + "\" changed to " << o << std::endl;
});
Attached is a full running example, which is now also part of the midas repository. I have tested most things, but would not yet use it in a production environment. Not 100% sure if there
are any memory leaks. If someone could valgrind the test program, I would appreciate (currently does not work on my Mac).
Have fun!
Stefan
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