Merging takes a pathname with unfilled components and supplies values for those components from a source of defaults.
If a component’s value is nil, that component is considered to be unfilled.
If a component’s value is any non-nil object,
including :unspecific
, that component is considered to be filled.
Except as explicitly specified otherwise, for functions that manipulate or inquire about files in the file system, the pathname argument to such a function is merged with *default-pathname-defaults* before accessing the file system (as if by merge-pathnames).
Examples of Merging Pathnames |