example.nim
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import lapp, tables
# This is a trivial example trying to cover all features of lapp.
let help = """
example [options] command filenames
-r Just an optional single character flag. Show the args using repr.
-a,--alpha Or with additional long variant, no whitespace there.
-n: A colon can be added, but has no meaning, instead () specifies further.
-N (default 10) And it can take a value, and have a default value.
-f (default 0.04) And be a float
-s (default banana) Or a string
-x (int) And it can be typed with int, string, float, stdin, stdout - without a
default value. This implies that the option is mandatory!
-X (int...) And allow multiples.
-v,--verbose: (bool...) Verbosity level, "..." means can be multiple.
-o,--out (default stdout) A file to direct to.
<command> Arguments are string by default.
<file>: (default stdin...) One or more files or stdin by default
The first line in this help text is arbitrary, or rather
its only the lines (trimmed) beginning with '-' or '<' that constitute
the speciciation, so this text is also ignored.
Things we know are not working:
ranges. The lexer in lapp does it, but there is no more support.
"""
# We call `parse` in lapp with our help text as argument.
# This will both parse the help text above and then, parse the
# arguments passed to this program. A table is returned
# with all command line elements in it, keyed by their name
# and with a PValue as value.
var args = parse(help)
# Let's examine what we got using repr
for k,v in args:
echo "Parameter: " & k & " PValue: " & repr(v)
# Or print out a bit cleaner
echo "Parameters and their values:"
echo "r == " & $args["r"].asBool
echo "alpha == " & $args["alpha"].asBool # Long name is used as key, if its specified
echo "n == " & $args["n"].asBool
echo "N == " & $args["N"].asInt
echo "f == " & $args["f"].asFloat
echo "s == " & $args["s"].asString
echo "x == " & $args["x"].asInt
echo "X == " & $args["X"].asSeq.map(proc(x:PValue):int = x.asInt)
echo "verbose == " & $args["verbose"].asSeq.len
echo "out == " & $args["out"].filename
echo "command == " & $args["command"].asString
echo "file == " & $args["file"].asSeq.map(proc(x:PValue):string = x.filename)