[patatools] Replace subcommand manipulation by module `argdispatch` (#214)

* [patatools] Replace subcommand manipulation by module `argdispatch`

* [patatools] Behave well when no subcommand is given

* [pylint] Remove useless import, and fix import ordering

patacrep/tools/__main__.py

@@ -2,85 +2,26 @@
 
 """Command line client to :mod:`tools`"""
 
-import argparse
 import logging
-import operator
-import os
-import pkgutil
-import re
 import sys
 
+import argdispatch
+
 import patacrep
 
 # Logging configuration
 logging.basicConfig(level=logging.INFO)
 LOGGER = logging.getLogger("patatools")
 
-def _execlp(program, args):
-    """Call :func:`os.execlp`, adding `program` as the first argument to itself."""
-    return os.execlp(program, program, *args)
-
-def _iter_subcommands():
-    """Iterate over subcommands.
-
-    The objects returned are tuples of:
-    - the name of the command;
-    - its description;
-    - the function to call to execute the subcommand.
-    """
-    subcommands = []
-
-    # Get python subcommands
-    path = [os.path.join(item, "patacrep", "tools") for item in sys.path]
-    prefix = "patacrep.tools."
-    module_re = re.compile(r'{}(?P<subcommand>[^\.]*)\.__main__'.format(prefix))
-    for module_loader, name, _ in pkgutil.walk_packages(path, prefix):
-        match = module_re.match(name)
-        if match:
-            module = module_loader.find_module(match.string).load_module()
-            if hasattr(module, "SUBCOMMAND_DESCRIPTION"):
-                subcommands.append(match.groupdict()['subcommand'])
-                yield (
-                    match.groupdict()['subcommand'],
-                    getattr(module, "SUBCOMMAND_DESCRIPTION"),
-                    module.main,
-                    )
-
-class ArgumentParser(argparse.ArgumentParser):
-    """Proxy class to circumvent an :mod:`argparse` bug.
-
-    Contrarily to what documented, the `argparse.REMAINDER
-    <https://docs.python.org/3/library/argparse.html#nargs>`_ `nargs` setting
-    does not include the remainder arguments if the first one begins with `-`.
-
-    This bug is reperted as `17050 <https://bugs.python.org/issue17050>`_. This
-    class can be deleted once this bug has been fixed.
-    """
-
-    def parse_args(self, args=None, namespace=None):
-        if args is None:
-            args = sys.argv[1:]
-        subcommands = [command[0] for command in set(_iter_subcommands())]
-        if len(args) > 0:
-            if args[0] in subcommands:
-                args = [args[0], "--"] + args[1:]
-
-        value = super().parse_args(args, namespace)
-
-        if hasattr(value, 'remainder'):
-            value.remainder = value.remainder[1:]
-        return value
-
-
 def commandline_parser():
     """Return a command line parser."""
 
-    parser = ArgumentParser(
+    parser = argdispatch.ArgumentParser(
         prog="patatools",
         description=(
             "Miscellaneous tools for patacrep."
             ),
-        formatter_class=argparse.RawTextHelpFormatter,
+        formatter_class=argdispatch.RawTextHelpFormatter,
         )
 
     parser.add_argument(
@@ -96,11 +37,7 @@ def commandline_parser():
         )
     subparsers.required = True
     subparsers.dest = "subcommand"
-
+    subparsers.add_submodules("patacrep.tools")
-    for command, message, function in sorted(_iter_subcommands(), key=operator.itemgetter(0)):
-        sub1 = subparsers.add_parser(command, help=message, add_help=False)
-        sub1.add_argument('remainder', nargs=argparse.REMAINDER)
-        sub1.set_defaults(function=function)
 
     return parser
 
@@ -108,9 +45,7 @@ def main(args=None):
     """Main function"""
     if args is None:
         args = sys.argv
-    parser = commandline_parser()
+    commandline_parser().parse_args(args[1:])
-    args = parser.parse_args(args[1:])
-    args.function(["patatools-{}".format(args.subcommand)] + args.remainder)
 
 if __name__ == "__main__":
     main()

patacrep/tools/cache/__main__.py

@@ -1,4 +1,4 @@
-"""`patatools cache` command: cache manipulation."""
+"""Perform operations on cache."""
 
 import argparse
 import logging
@@ -11,7 +11,6 @@ from patacrep import errors
 from patacrep.songbook import open_songbook
 
 LOGGER = logging.getLogger("patatools.cache")
-SUBCOMMAND_DESCRIPTION = "Perform operations on cache."
 
 def filename(name):
     """Check that argument is an existing, readable file name.
@@ -27,7 +26,7 @@ def commandline_parser():
 
     parser = argparse.ArgumentParser(
         prog="patatools cache",
-        description=SUBCOMMAND_DESCRIPTION,
+        description="Convert between song formats.",
         formatter_class=argparse.RawTextHelpFormatter,
         )
 

patacrep/tools/convert/__main__.py

@@ -1,4 +1,4 @@
-"""`patatools.convert` command: convert between song formats"""
+"""Convert between song formats."""
 
 import os
 import logging
@@ -10,7 +10,6 @@ from patacrep.utils import yesno
 from patacrep.build import config_model
 
 LOGGER = logging.getLogger("patatools.convert")
-SUBCOMMAND_DESCRIPTION = "Convert between song formats"
 
 def _usage():
     return "patatools convert INPUTFORMAT OUTPUTFORMAT FILES"

setup.py

@@ -34,7 +34,7 @@ setup(
     packages=find_packages(exclude=["test*"]),
     license="GPLv2 or any later version",
     install_requires=[
-        "unidecode", "jinja2", "ply", "pyyaml",
+        "argdispatch", "unidecode", "jinja2", "ply", "pyyaml",
         ],
     entry_points={
         'console_scripts': [