Comment by socalgal2
9 hours ago
it's not a terrible idea. It has it's uses. You just have to know when to use it and when not to use it.
For example, to have fast load times and zero temp memory overhead I've used that for several games. Other than changing a few offsets to pointers the data is used directly. I don't have to worry about incompatibilities. Either I'm shipping for a single platform or there's a different build for each platform, including the data. There's a version in the first few bytes just so during dev we don't try to load old format files with new struct defs. But otherwise, it's great for getting fast load times.
To support your point, it's also used in basically every shared library / DLL system. While usually used "for code", a "shared pure data library" has many applications. There are also 3rd party tools to make this convenient from many PLangs like HDF5, https://github.com/c-blake/nio with its FileArray for Nim, Apache Arrow, etc.
Unmentioned so far is that defaults for max live memory maps are usually much higher than defaults for max open files. So, if you are careful about closing files after mapping, you can usually get more "range" before having to move from OS/distro defaults. (E.g. for `program foo*`-style work where you want to keep the foo open for some reason, like binding them to many read-only NumPy array variables.)