doc: why expanduser used internally [skip ci]

Author: scivision

+stdlib/+fileio/absolute_path.m

@@ -4,7 +4,7 @@
   p string {mustBeScalarOrEmpty}
 end
 
-% have to expand ~ first
+% have to expand ~ first (like C++ filesystem::path::absolute)
 abspath = stdlib.fileio.expanduser(p);
 
 if isempty(abspath)

+stdlib/+fileio/is_absolute_path.m

@@ -4,6 +4,7 @@
   apath string
 end
 
+% leave expanduser() here to work like C++ filesystem::path::is_absolute()
 apath = stdlib.fileio.expanduser(apath);
 
 if ispc

+stdlib/+fileio/makedir.m

@@ -4,6 +4,7 @@ function makedir(direc)
   direc (1,1) string {mustBeNonzeroLengthText}
 end
 
+%% to avoid confusing making ./~/mydir
 direc = stdlib.fileio.expanduser(direc);
 
 if isfolder(direc)

+stdlib/+fileio/which.m

@@ -1,5 +1,5 @@
 function exe = which(filename, fpath)
-
+%% which  like Python shutil.which, find executable in fpath or env var PATH
 arguments
   filename (1,1) string {mustBeNonzeroLengthText}
   fpath (1,:) string = getenv('PATH')
@@ -28,6 +28,7 @@
 % path given
 
 if isscalar(fpath)
+  % PATH could have ~/ prefixed paths in it
   fpath = split(stdlib.fileio.expanduser(fpath), pathsep).';
 end
 fpath = fpath(strlength(fpath)>0);

+stdlib/+hdf5nc/h5create_group.m

@@ -18,6 +18,7 @@
 if isa(file, 'H5ML.id')
   fid = file;
 else
+  % avoid confusing creating file ./~/foo.h5
   file = stdlib.fileio.expanduser(file);
   dcpl = 'H5P_DEFAULT';
   if isfile(file)

+stdlib/+hdf5nc/h5save.m

@@ -12,6 +12,7 @@ function h5save(filename, varname, A, opts)
   mustBeReal(A)
 end
 
+% avoid confusing creating file ./~/foo.h5
 filename = stdlib.fileio.expanduser(filename);
 
 % coerce if needed

+stdlib/+hdf5nc/ncsave.m

@@ -12,6 +12,7 @@ function ncsave(filename, varname, A, opts)
   mustBeReal(A)
 end
 
+% avoid creating confusing file ./~/foo.nc
 filename = stdlib.fileio.expanduser(filename);
 
 if isempty(opts.dims)