I'm pretty new to vim, and I'm having a hard time understanding some subtleties with vim scripting. Specifically, I'm having trouble working with commands that expect an unquoted-string (is there a name for this?). For example

cd some/unquoted/string/path

The problem is that I'd like to pass a variable, but calling

let pathname = 'some/path'
cd pathname

will try to change the current directory to 'pathname' instead of 'some/path'. One way around this is to use

let cmd = 'cd ' . pathname
execute cmd

but this seems a bit roundabout. This StackOverflow question actually uses cd with a variable, but it doesn't work on my system ("a:path" is treated as the path as described above).

I'm using cd as a specific example, but this behavior isn't unique to cd; for example, the edit command also behaves this way. (Is there a name for this type of command?)