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Diffstat (limited to 'examples/scripts.noah/require.bash')
| -rw-r--r-- | examples/scripts.noah/require.bash | 182 |
1 files changed, 0 insertions, 182 deletions
diff --git a/examples/scripts.noah/require.bash b/examples/scripts.noah/require.bash deleted file mode 100644 index f38040a3..00000000 --- a/examples/scripts.noah/require.bash +++ /dev/null @@ -1,182 +0,0 @@ -# require.bash -# Author: Noah Friedman <friedman@prep.ai.mit.edu> -# Created: 1992-07-08 -# Last modified: 1993-09-29 -# Public domain - -# Commentary: - -# These functions provide an interface based on the lisp implementation for -# loading libraries when they are needed and eliminating redundant loading. -# The basic idea is that each "package" (or set of routines, even if it is -# only one function) registers itself with a symbol that marks a "feature" -# as being "provided". If later you "require" a given feature, you save -# yourself the trouble of explicitly loading it again. -# -# At the bottom of each package, put a "provide foobar", so when another -# package has a "require foobar", it gets loaded and registered as a -# "feature" that won't need to get loaded again. (See warning below for -# reasons why provide should be put at the end.) -# -# The list of provided features are kept in the `FEATURES' variable, which -# is not exported. Care should be taken not to munge this in the shell. -# The search path comes from a colon-separated `FPATH' variable. It has no -# default value and must be set by the user. -# -# Require uses `fpath_search', which works by scanning all of FPATH for a -# file named the same as the required symbol but with a `.bash' appended to -# the name. If that is found, it is loaded. If it is not, FPATH is -# searched again for a file name the same as the feature (i.e. without any -# extension). Fpath_search may be useful for doing library filename -# lookups in other functions (such as a `load' or `autoload' function). -# -# Warning: Because require ultimately uses the builtin `source' command to -# read in files, it has no way of undoing the commands contained in the -# file if there is an error or if no provide statement appeared (this -# differs from the lisp implementation of require, which normally undoes -# most of the forms that were loaded if the require fails). Therefore, to -# minize the number of problems caused by requiring a faulty package (such -# as syntax errors in the source file) it is better to put the provide at -# the end of the file, rather than at the beginning. - -# Code: - -# Exporting this variable would cause considerable lossage, since none of -# the functions are exported (or at least, they're not guaranteed to be) -export -n FEATURES - -#:docstring : -# Null function. Provided only so that one can put page breaks in source -# files without any ill effects. -#:end docstring: -# -# (\\014 == C-l) -eval "function $(echo -e \\014) () { : }" - - -#:docstring featurep: -# Usage: featurep argument -# -# Returns 0 (true) if argument is a provided feature. Returns 1 (false) -# otherwise. -#:end docstring: - -###;;;autoload -function featurep () -{ - local feature="$1" - - case " ${FEATURES} " in - *" ${feature} "* ) return 0 ;; - esac - - return 1 -} - - -#:docstring provide: -# Usage: provide symbol ... -# -# Register a list of symbols as provided features -#:end docstring: - -###;;;autoload -function provide () -{ - local feature - - for feature in "$@" ; do - if ! featurep "${feature}" ; then - FEATURES="${FEATURES} ${feature}" - fi - done - - return 0 -} - - -#:docstring require: -# Usage: require feature {file} -# -# Load FEATURE if it is not already provided. Note that require does not -# call `provide' to register features. The loaded file must do that -# itself. If the package does not explicitly do a `provide' after being -# loaded, require will complain about the feature not being provided on -# stderr. -# -# Optional argument FILE means to try to load FEATURE from FILE. If no -# file argument is given, require searches through FPATH (see fpath_search) -# for the appropriate file. -# -# If the variable REQUIRE_FAILURE_FATAL is set, require will cause the -# current shell invocation to exit, rather than merely return. This may be -# useful for a shell script that vitally depends on a package. -# -#:end docstring: - -###;;;autoload -function require () -{ - local feature="$1" - local path="$2" - local file - - if ! featurep "${feature}" ; then - file=$(fpath_search "${feature}" "${path}") && source "${file}" - - if ! featurep "${feature}" ; then - echo "require: ${feature}: feature was not provided." 1>&2 - if [ "${REQUIRE_FAILURE_FATAL+set}" = "set" ]; then - exit 1 - fi - return 1 - fi - fi - - return 0 -} - -#:docstring fpath_search: -# Usage: fpath_search filename {path ...} -# -# Search $FPATH for `filename' or, if `path' (a list) is specified, search -# those directories instead of $FPATH. First the path is searched for an -# occurrence of `filename.bash, then a second search is made for just -# `filename'. -#:end docstring: - -###;;;autoload -function fpath_search () -{ - local name="$1" - local path="$2" - local suffix=".bash" - local file - - if [ -z "${path}" ]; then path="${FPATH}"; fi - - for file in "${name}${suffix}" "${name}" ; do - set -- $(IFS=':' - set -- ${path} - for p in "$@" ; do - echo -n "${p:-.} " - done) - - while [ $# -ne 0 ]; do - test -f "${1}/${file}" && { file="${1}/${file}"; break 2 } - shift - done - done - - if [ $# -eq 0 ]; then - echo "fpath_search: ${name}: file not found in fpath" 1>&2 - return 1 - fi - - echo "${file}" - return 0 -} - -provide require - -# require.bash ends here |