Cleaner command support

Author: einarf

demosys/core/management/__init__.py

@@ -19,26 +19,26 @@ def local_command_dir():
     return command_dir
 
 
-def load_command_class(name):
-    return import_module('demosys.core.management.commands.{}'.format(name))
+def load_command_class(app_name, name):
+    module = import_module(f'{app_name}.management.commands.{name}')
+    return module.Command()
 
 
 def execute_from_command_line(argv=None):
+    """
+    Currently the only entrypoint (manage.py, demosys-admin)
+    """
     if not argv:
         argv = sys.argv
+
+    # prog_name = argv[0]
     commands = find_commands(local_command_dir())
     command = argv[1] if len(argv) > 1 else None
 
-    source = os.path.basename(argv[0])
-    if source == "demosys-admin":
-        print("Running as demosys-admin")
-
     if command in commands:
-        module = load_command_class(command)
-        if hasattr(module, 'run'):
-            module.run(argv[2:])
-        else:
-            print("Command {} is not runnable".format(command))
+        cmd = load_command_class('demosys.core', command)
+        cmd.run_from_argv(argv)
     else:
         print("Available commands:")
-        print("\n".join(commands))
+        for c in commands:
+            print(f" - {c}")

demosys/core/management/base.py

@@ -0,0 +1,64 @@
+import argparse
+from importlib import import_module
+
+
+class CommandError(Exception):
+    pass
+
+
+class BaseCommand:
+    help = ''
+
+    def __init__(self):
+        """should take cmd config"""
+        pass
+
+    def add_arguments(self, parser):
+        pass
+
+    def handle(self, *args, **options):
+        raise NotImplementedError
+
+    def run_from_argv(self, argv):
+        parser = self.create_parser(argv[0], argv[1])
+        options = parser.parse_args(argv[2:])
+        cmd_options = vars(options)
+        args = cmd_options.pop('args', ())
+        self.handle(*args, **cmd_options)
+
+    def print_help(self, prog_name, subcommand):
+        parser = self.create_parser(prog_name, subcommand)
+        parser.print_help()
+
+    def create_parser(self, prog_name, subcommand):
+        """
+        Create argument parser and deal with ``add_arguments``.
+        :param prog_name: Name of the command (argv[0])
+        :return: ArgumentParser
+        """
+        parser = argparse.ArgumentParser(prog_name, subcommand)
+        # Add generic arguments here
+        self.add_arguments(parser)
+        return parser
+
+
+class CreateCommand(BaseCommand):
+    """Used for createproject and createeffect"""
+
+    def validate_name(self, name):
+        """Can the name be used as a python module or package?"""
+        if not name:
+            raise ValueError("Name cannot be empty")
+
+        # Can the name be used as an identifier in python (module or package name)
+        if not name.isidentifier():
+            raise ValueError(f"{name} is not a valid identifier")
+
+    def try_import(self, name):
+        """Attemt to import the name"""
+        try:
+            import_module(name)
+        except ImportError:
+            pass
+        else:
+            raise ValueError(f"{name} conflicts with an existing python module")

demosys/core/management/commands/createeffect.py

@@ -0,0 +1,23 @@
+import os
+from demosys.core.management.base import CreateCommand
+
+
+class Command(CreateCommand):
+    help = "Create an effect"
+
+    def add_arguments(self, parser):
+        parser.add_argument("name", help="Name of the effect")
+
+    def handle(self, *args, **options):
+        name = options['name']
+
+        # Check for python module collision
+        self.try_import(name)
+
+        # Is the name a valid identifier?
+        self.validate_name(name)
+
+        # Make sure we don't mess with existing directories
+        if os.path.exists(name):
+            print(f"Directory {name} already exist. Aborting.")
+            return

demosys/core/management/commands/createproject.py

@@ -1,65 +1,47 @@
-# FIXME: Rewrite this into something less horrible in the future
-# Right now we just want this to work
 import os
-from importlib import import_module
+from demosys.core.management.base import CreateCommand
 
-HELP = "Create a project"
 
+class Command(CreateCommand):
+    help = "Create a project"
 
-def print_usage():
-    print("Usage:")
-    print("  crateproject <name>")
+    def add_arguments(self, parser):
+        parser.add_argument("name", help="Name of the project")
 
+    def handle(self, *args, **options):
+        name = options['name']
 
-def run(args):
-    if not args:
-        print_usage()
-        return
+        # Check for python module collision
+        self.try_import(name)
 
-    name = args[0]
-    print(f"Creating project '{name}'")
+        # Is the name a valid identifier?
+        self.validate_name(name)
 
-    # Check for python module collision
-    try:
-        import_module(name)
-    except ImportError:
-        pass
-    else:
-        raise ValueError(f"{name} conflicts with an existing python module")
+        # Make sure we don't mess with existing directories
+        if os.path.exists(name):
+            print(f"Directory {name} already exist. Aborting.")
+            return
 
-    # Is the name a valid identifier?
-    validate_name(name)
+        manage_file = 'manage.py'
+        if os.path.exists(manage_file):
+            print("A manage.py file already exist in the current directory. Aborting.")
+            return
 
-    # Make sure we don't mess with existing directories
-    if os.path.exists(name):
-        print(f"Directory {name} already exist. Aborting.")
-        return
+        # Create the project directory
+        os.makedirs(name)
 
-    # Create the project directory
-    os.makedirs(name)
+        # Use the default settings file
+        os.environ['DEMOSYS_SETTINGS_MODULE'] = 'demosys.conf.default_settings'
+        from demosys.conf import settings
+        from demosys.conf import settingsfile
 
-    # Use the default settings file
-    os.environ['DEMOSYS_SETTINGS_MODULE'] = 'demosys.conf.default_settings'
-    from demosys.conf import settings
-    from demosys.conf import settingsfile
+        with open(os.path.join(name, 'settings.py'), 'w') as fd:
+            fd.write(settingsfile.create(settings))
 
-    with open(os.path.join(name, 'settings.py'), 'w') as fd:
-        fd.write(settingsfile.create(settings))
+        with open(manage_file, 'w') as fd:
+            fd.write(gen_manage_py(name))
 
-    manage_file = 'manage.py'
-    with open(manage_file, 'w') as fd:
-        fd.write(gen_manage_py(name))
-
-    os.chmod(manage_file, 0o777)
-
-
-def validate_name(name):
-    if not name:
-        raise ValueError("Name cannot be empty")
-
-    # Can the name be used as an identifier in python (module or package name)
-    if not name.isidentifier():
-        raise ValueError(f"{name} is not a valid identifier")
+        os.chmod(manage_file, 0o777)
 
 
 def gen_manage_py(project_name):