static ryml::Tree

[parihaaraka]

Hello. Could you please explain the tree's memory handling details in v.0.3?
Previously i had to define static MemoryResourceCallbacks before static Tree to let the first one to stay alive until the tree being destructed. Is it still an issue?

[biojppm]

Here's an example:

    // Using static trees may incur a static initialization order problem.
    // This happens because a default-constructed tree will obtain
    // the callbacks from the current global setting, which may
    // not have been initialized due to undefined static initialization
    // order:
    //
    //static ryml::Tree tree;  // ERROR! depends on ryml::get_callbacks() which may not have been initialized.
    //
    // To work around the issue, declare static callbacks
    // to explicitly initialize the static tree:
    static ryml::Callbacks callbacks = {}; // use default callback members
    static ryml::Tree tree(callbacks); // OK
    // now you can use the tree just as normal:
    ryml::parse_in_arena(R"(doe: "a deer, a female deer")", &tree);
    CHECK(tree["doe"].val() == "a deer, a female deer");

I will add this example to the quickstart.