A modest config file loader library
MODEST-CONFIG is a simple configuration file parser for Common Lisp. Config files contain a single Common Lisp property list, and the parser provides a convenient way to extract the properties.
Given a config file:
( ;; This sets property FOO foo :some-value ;; Here is another property bar "This is a string" zot (list 1 2 3 4 5) ;; Config may also contain functions ;; ... if you are willing to trust your config maintainer quux (lambda (wombat) (format nil "Hello, ~a" wombat)) )
When you load and extract properties like this:
(with-config "example.config" (zot bar quux) (format t "The value of zot is ~s~%" zot) (format t "~a says bar~%" bar) (format t "(quux \"World\") => ~s~%" (funcall (eval quux) "World")))
Then you get this output:
The value of zot is (1 2 3 4 5) This is a string says bar (quux "World") => "Hello, World"
The system only contain the package
modest-config, which also has the nickname
modest. There are no external dependencies.
find-config &optional identifier => pathname
load-config &optional identifier => plist
with-config identifier bindings &body body => result, plist
Arguments and values:
identifier -- an object used to identify what config source to use. May be pathname, string, symbol, plist, stream, or nil (details further down).
pathname -- the path to a config file.
plist -- a property list containing the configuration.
bindings -- a list of symbols that will be bound to values from configuration.
body -- forms that will be evaluated in a progn.
result -- the result of evaluating the last expression of body
with-config also returns the entire configuration property list as it's second value.
Locating the config file
Configuration will be loaded based on the following rules:
|Identifier type||What will happen?|
|pathname||File designated by pathname is assumed to contain configuration.|
|string||Will be turned into a pathname and handled as such.|
|symbol||If identifier is |
|list||Is assumed to be a property list containing the actual configuration. This will fail if passed to |
|stream||Config will be read from stream. This will fail if passed to |
|null||If the identifier is nil these three locations will be tried is sequence: 1) Package.config in the current directory, where package is the name of the current package. 2) modest.config in the current directory. 3) package.config in the home directory of the current user.|
All functions may invoke an error condition if a configuration file can't be located.
Copyright 2017 Torbjørn Marø
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