Merge lp:~mew/charm-helpers/commandant into lp:~nick-moffitt/charm-helpers/commandant

[Matthew Wedgwood]

This is more advisory than anything else. I've continued in your footsteps.

[lp:~mew/charm-helpers/commandant]

24. By Matthew Wedgwood on 2013-06-19

command line interface that works. placement of subcommand module isn't right, but it's illustrative

[Nick Moffitt (nick-moffitt)]

review: Approve

=== added file 'bin/chlp'
--- bin/chlp	1970-01-01 00:00:00 +0000
+++ bin/chlp	2013-06-19 23:02:29 +0000
@@ -0,0 +1,7 @@
+#!/usr/bin/env python
+
+from charmhelpers.cli import cmdline
+from charmhelpers.cli.commands import *
+
+if __name__ == '__main__':
+    cmdline.run()
 
=== renamed directory 'charmhelpers/commandant' => 'charmhelpers/cli'
=== modified file 'charmhelpers/cli/README.rst'
--- charmhelpers/commandant/README.rst	2013-06-06 17:29:26 +0000
+++ charmhelpers/cli/README.rst	2013-06-19 23:02:29 +0000
@@ -14,6 +14,7 @@
 =====
 
 * Single decorator to expose a function as a command.
+  * now two decorators - one "automatic" and one that allows authors to manipulate the arguments for fine-grained control.(MW)
 * Automatic analysis of function signature through ``inspect.getargspec()``
 * Command argument parser built automatically with ``argparse``
 * Interactive interpreter loop object made with ``Cmd``
@@ -30,5 +31,27 @@
     - We could automatically detect arguments that default to False or True, and automatically support --no-foo for foo=True.
     - We could automatically support hyphens as alternates for underscores
     - Arguments defaulting to sequence types could support the ``append`` action.
-    
-
+
+
+-----------------------------------------------------
+Implementing subcommands
+-----------------------------------------------------
+
+(WIP)
+
+So as to avoid dependencies on the cli module, subcommands should be defined separately from their implementations. The recommmendation would be to place definitions into separate modules near the implementations which they expose.
+
+Some examples::
+
+    from charmhelpers.cli import CommandLine
+    from charmhelpers.payload import execd
+    from charmhelpers.foo import bar
+
+    cli = CommandLine()
+
+    cli.subcommand(execd.execd_run)
+
+    @cli.subcommand_builder("bar", help="Bar baz qux")
+    def barcmd_builder(subparser):
+        subparser.add_argument('argument1', help="yackety")
+        return bar
 
=== renamed file 'charmhelpers/commandant/signature.py' => 'charmhelpers/cli/__init__.py'
--- charmhelpers/commandant/signature.py	2013-06-06 16:58:35 +0000
+++ charmhelpers/cli/__init__.py	2013-06-19 23:02:29 +0000
@@ -1,14 +1,73 @@
-"""Tools to inspect function signatures and build argparse parsers from
-them."""
-
 import inspect
 import itertools
+import argparse
+
+
+class CommandLine(object):
+    argument_parser = None
+    subparsers = None
+
+    def __init__(self):
+        if not self.argument_parser:
+            self.argument_parser = argparse.ArgumentParser(description='Perform common charm tasks')
+        if not self.subparsers:
+            self.subparsers = self.argument_parser.add_subparsers(help='Commands')
+
+    def subcommand(self, command_name=None):
+        """
+        Decorate a function as a subcommand. Use its arguments as the
+        command-line arguments"""
+        def wrapper(decorated):
+            cmd_name = command_name or decorated.__name__
+            subparser = self.subparsers.add_parser(cmd_name,
+                                                   description=decorated.__doc__)
+            for args, kwargs in describe_arguments(decorated):
+                subparser.add_argument(*args, **kwargs)
+            subparser.set_defaults(func=decorated)
+            return decorated
+        return wrapper
+
+    def subcommand_builder(self, command_name, description=None):
+        """
+        Decorate a function that builds a subcommand. Builders should accept a
+        single argument (the subparser instance) and return the function to be
+        run as the command."""
+        def wrapper(decorated):
+            subparser = self.subparsers.add_parser(command_name)
+            func = decorated(subparser)
+            subparser.set_defaults(func=func)
+            subparser.description = description or func.__doc__
+        return wrapper
+
+    def make_subparser(self, subcmd_name, function, description=None):
+        "An argparse subparser for the named subcommand."
+        subparser = self.subparsers.add_parser(subcmd_name, description)
+        subparser.set_defaults(func=function)
+        return subparser
+
+    def run(self):
+        "Run cli, processing arguments and executing subcommands."
+        arguments = self.argument_parser.parse_args()
+        argspec = inspect.getargspec(arguments.func)
+        vargs = []
+        kwargs = {}
+        if argspec.varargs:
+            vargs = getattr(arguments, argspec.vargs)
+        for arg in argspec.args:
+            kwargs[arg] = getattr(arguments, arg)
+        arguments.func(*vargs, **kwargs)
+
+
+cmdline = CommandLine()
+
 
 def describe_arguments(func):
-    """Analyze a function's signature and return a data structure suitable for
+    """
+    Analyze a function's signature and return a data structure suitable for
     passing in as arguments to an argparse parser's add_argument() method."""
 
     argspec = inspect.getargspec(func)
+    # we should probably raise an exception somewhere if func includes **kwargs
     if argspec.defaults:
         positional_args = argspec.args[:len(argspec.defaults)]
         keyword_names = argspec.args[-len(argspec.defaults):]
@@ -21,6 +80,3 @@
         yield (arg,), {}
     if argspec.varargs:
         yield (argspec.varargs,), {'nargs': '*'}
-
-
-
 
=== added file 'charmhelpers/cli/commands.py'
--- charmhelpers/cli/commands.py	1970-01-01 00:00:00 +0000
+++ charmhelpers/cli/commands.py	2013-06-19 23:02:29 +0000
@@ -0,0 +1,2 @@
+from . import CommandLine
+import host
 
=== added file 'charmhelpers/cli/host.py'
--- charmhelpers/cli/host.py	1970-01-01 00:00:00 +0000
+++ charmhelpers/cli/host.py	2013-06-19 23:02:29 +0000
@@ -0,0 +1,16 @@
+from . import cmdline
+from charmhelpers.core import host
+
+
[e-mail]()
+def mounts():
+    "List mounts"
+    for mount in host.mounts():
+        print mount
+
+
[e-mail]_builder('service', description="Control system services")
+def service(subparser):
+    subparser.add_argument("action", help="The action to perform (start, stop, etc...)")
+    subparser.add_argument("service_name", help="Name of the service to control")
+    return host.service
 
=== removed file 'charmhelpers/commandant/__init__.py'
=== modified file 'charmhelpers/core/host.py'
--- charmhelpers/core/host.py	2013-05-30 11:02:07 +0000
+++ charmhelpers/core/host.py	2013-06-19 23:02:29 +0000
@@ -22,6 +22,7 @@
 
 
 def service(action, service_name):
+    "Control system services"
     cmd = None
     if os.path.exists(os.path.join('/etc/init', '%s.conf' % service_name)):
         cmd = ['initctl', action, service_name]