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(slib.info)Vicinity

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Vicinity
--------

A vicinity is a descriptor for a place in the file system.  Vicinities
hide from the programmer the concepts of host, volume, directory, and
version.  Vicinities express only the concept of a file environment
where a file name can be resolved to a file in a system independent
manner.  Vicinities can even be used on "flat" file systems (which have
no directory structure) by having the vicinity express constraints on
the file name.  On most systems a vicinity would be a string.  All of
these procedures are file system dependent.

These procedures are provided by all implementations.

 - Function: make-vicinity path
     Returns the vicinity of PATH for use by `in-vicinity'.

 - Function: program-vicinity
     Returns the vicinity of the currently loading Scheme code.  For an
     interpreter this would be the directory containing source code.
     For a compiled system (with multiple files) this would be the
     directory where the object or executable files are.  If no file is
     currently loading it the result is undefined.  *Warning:*
     `program-vicinity' can return incorrect values if your program
     escapes back into a `load'.

 - Function: library-vicinity
     Returns the vicinity of the shared Scheme library.

 - Function: implementation-vicinity
     Returns the vicinity of the underlying Scheme implementation.  This
     vicinity will likely contain startup code and messages and a
     compiler.

 - Function: user-vicinity
     Returns the vicinity of the current directory of the user.  On most
     systems this is `""' (the empty string).

 - Function: home-vicinity
     Returns the vicinity of the user's "HOME" directory, the directory
     which typically contains files which customize a computer
     environment for a user.  If scheme is running without a user (eg.
     a daemon) or if this concept is meaningless for the platform, then
     `home-vicinity' returns `#f'.

 - Function: in-vicinity vicinity filename
     Returns a filename suitable for use by `slib:load',
     `slib:load-source', `slib:load-compiled', `open-input-file',
     `open-output-file', etc.  The returned filename is FILENAME in
     VICINITY.  `in-vicinity' should allow FILENAME to override
     VICINITY when FILENAME is an absolute pathname and VICINITY is
     equal to the value of `(user-vicinity)'.  The behavior of
     `in-vicinity' when FILENAME is absolute and VICINITY is not equal
     to the value of `(user-vicinity)' is unspecified.  For most systems
     `in-vicinity' can be `string-append'.

 - Function: sub-vicinity vicinity name
     Returns the vicinity of VICINITY restricted to NAME.  This is used
     for large systems where names of files in subsystems could
     conflict.  On systems with directory structure `sub-vicinity' will
     return a pathname of the subdirectory NAME of VICINITY.