I want to define a number of functions for use from the command line and in scripts. One way would be to create one file for every function, and store them in the autoloading folder (e.g. ~/config/fish/functions/one.fish, ~/config/fish/functions/two.fish, ...)
But I don't want to maintain each function in its own file. Is there any way to define a collection of functions in a single file (such that they can be referenced from the command line and from multiple scripts)?
(Alternatively, fish is guided by strong design principles. If there is a documented fish-was-designed-this-way rationale to store one file per user-defined function, I'd like to see it.)
You can just have multiple functions in a single file, but you can only use autoloading for one of them.
The issue is this: If you have a function "foo" and a function "bar" in a file, how is fish supposed to know that, without reading the file first?
For autoloading, the file is named after the function (e.g. "bar" would be stored in "bar.fish"), so fish can figure out where it is.
So, you can do one of two things:
If one of the functions is always called first, then you can use that as the file name and store it in a function file. After you've used that function, fish knows about the rest (since it sourced the file).
If that isn't the case (or you don't want to rely on it), you can either source the file manually whenever you need it (or just once at startup) or store it in a configuration snippet in ~/.config/fish/conf.d/SOMETHING.fish (which fish will source automatically right before reading config.fish).
The former means that e.g. helper functions can be stored along with the main one. The latter is a teensy bit slower when you're loading the file without using the function, but unless you're using this excessively you're unlikely to even notice.