* This prevents unnecessary conversions back and forth between rdcstr and const
char * when going through interfaces. In the OS specific layer this is rarely
an issue because most of the implementations don't convert to rdcstr, but it
is convenient to be able to pass in an rdcstr directly. The few cases where
there's an unecessary construction of an rdcstr is acceptable.
* A couple of places in the public API need to return a string from a global
function, so can't return an rdcstr due to C ABI, so they still return a const
char *.
* Similarly const char * is kept for logging, to avoid a dependency on rdcstr
and because that's one place where unnecessary conversions/constructions may
be impactful.
* This is a string type which heavily optimises for immutability and minimal
storage. It only contains one pointer to the string data and always
reallocates on modify. For compile-time literals it doesn't modify or
allocate.
* On x64 we use the top bit in a tagged pointer to store a flag of whether it's
heap or literal, on other platforms it uses a separate field (meaning another
pointer sized value effectively, including padding).
* This is best for structured data which tends to use a lot of immutable strings
for type/name information, and only a few for actual string data (which are
only allocated once and aren't modified after that). Similarly we rarely want
to know only the size of any of these strings, we want the whole string so not
explicitly storing the size is not a big deal.
* Overall this reduces SDObject from 128 bytes to 80 bytes.
* For certain very large arrays it can be nice to defer generation of structured
data until it's needed, since often maybe only a handful of elements may be
needed (or commonly none at all).
* This allows persistent config storage and registering tweak variables that
works independent of the UI's configuration.
* Config vars can be debug only, which means they will be compiled out in stable
version releases. This allows for debug-logging tweaks that are available in
all builds (including nightly builds) for diagnostic purposes, but have zero
overhead in stable releases.
* Variables have a loose hierarchy defined with _ or . to separate nodes.
baldurk