use argparse in colvars lib build

lib/colvars/Install.py

@@ -5,7 +5,12 @@
 from __future__ import print_function
 import sys,os,subprocess
 sys.path.append('..')
-from install_helpers import error,get_cpus
+from install_helpers import get_cpus
+
+from argparse import ArgumentParser
+
+parser = ArgumentParser(prog='Install.py',
+                        description="LAMMPS library build wrapper script")
 
 # help message
 
@@ -26,37 +31,33 @@ Examples:
 make lib-colvars args="-m mpi"     # build COLVARS lib with default mpi compiler wrapper
 """
 
-# parse args
-
-args = sys.argv[1:]
-nargs = len(args)
-if nargs == 0: error(help=help)
-
-machine = None
-extraflag = False
-
-iarg = 0
-while iarg < nargs:
-  if args[iarg] == "-m":
-    if iarg+2 > len(args): error(help=help)
-    machine = args[iarg+1]
-    iarg += 2
-  elif args[iarg] == "-e":
-    if iarg+2 > len(args): error(help=help)
-    extraflag = True
-    suffix = args[iarg+1]
-    iarg += 2
-  else: error(help=help)
-
 # set lib from working dir
 
 cwd = os.getcwd()
 lib = os.path.basename(cwd)
 
+# parse and process arguments
+
+parser.add_argument("-m", "--machine",
+                    help="suffix of a <libname>/Makefile.* or of a src/MAKE/MACHINES/Makefile.* file used for compiling this library")
+parser.add_argument("-e", "--extramake",
+                    help="set EXTRAMAKE variable in <libname>/Makefile.<machine> to Makefile.lammps.<extramake>")
+
+args = parser.parse_args()
+
+# print help message and exit, if neither build nor path options are given
+if not args.machine and not args.extramake:
+  parser.print_help()
+  sys.exit(help)
+
+machine = args.machine
+extraflag = args.extramake != None
+suffix = args.extramake
+
 def get_lammps_machine_flags(machine):
   """Parse Makefile.machine from LAMMPS, return dictionary of compiler flags"""
   if not os.path.exists("../../src/MAKE/MACHINES/Makefile.%s" % machine):
-    error("Cannot locate src/MAKE/MACHINES/Makefile.%s" % machine)
+    sys.exit("Cannot locate src/MAKE/MACHINES/Makefile.%s" % machine)
   lines = open("../../src/MAKE/MACHINES/Makefile.%s" % machine,
                'r').readlines()
   machine_flags = {}
@@ -102,7 +103,7 @@ if not os.path.exists("Makefile.%s" % machine):
   machine_flags = get_lammps_machine_flags(machine)
   gen_colvars_makefile_machine(machine, machine_flags)
 if not os.path.exists("Makefile.%s" % machine):
-  error("lib/%s/Makefile.%s does not exist" % (lib,machine))
+  sys.exit("lib/%s/Makefile.%s does not exist" % (lib,machine))
 
 # create Makefile.auto as copy of Makefile.machine
 # reset EXTRAMAKE if requested
@@ -131,6 +132,6 @@ except subprocess.CalledProcessError as e:
   sys.exit(1)
 
 if os.path.exists("lib%s.a" % lib): print("Build was successful")
-else: error("Build of lib/%s/lib%s.a was NOT successful" % (lib,lib))
+else: sys.exit("Build of lib/%s/lib%s.a was NOT successful" % (lib,lib))
 if not os.path.exists("Makefile.lammps"):
   print("lib/%s/Makefile.lammps was NOT created" % lib)