Add --only and --except command-line arguments

Internal to Dotbot, we use the name "skip" instead of "except", because
the latter is a keyword, and using a name like "except_" didn't seem as
nice.

README.md

@@ -8,6 +8,7 @@ Dotbot makes installing your dotfiles as easy as `git clone $url && cd dotfiles
 - [Configuration](#configuration)
 - [Directives](#directives) ([Link](#link), [Create](#create), [Shell](#shell), [Clean](#clean), [Defaults](#defaults))
 - [Plugins](#plugins)
+- [Command-line Arguments](#command-line-arguments)
 - [Wiki][wiki]
 
 ---
@@ -359,6 +360,23 @@ Plugins are loaded using the `--plugin` and `--plugin-dir` options, using
 either absolute paths or paths relative to the base directory. It is
 recommended that these options are added directly to the `install` script.
 
+## Command-line Arguments
+
+Dotbot takes a number of command-line arguments; you can run Dotbot with
+`--help`, e.g. by running `./install --help`, to see the full list of options.
+Here, we highlight a couple that are particularly interesting.
+
+### `--only`
+
+You can call `./install --only [list of directives]`, such as `./install --only
+link`, and Dotbot will only run those sections of the config file.
+
+### `--except`
+
+You can call `./install --except [list of directives]`, such as `./install
+--except shell`, and Dotbot will run all the sections of the config file except
+the ones listed.
+
 ## Wiki
 
 Check out the [Dotbot wiki][wiki] for more information, tips and tricks,

dotbot/cli.py

@@ -28,6 +28,10 @@ def add_options(parser):
         action='store_true', help='disable built-in plugins')
     parser.add_argument('--plugin-dir', action='append', dest='plugin_dirs', default=[],
         metavar='PLUGIN_DIR', help='load all plugins in PLUGIN_DIR')
+    parser.add_argument('--only', nargs='+',
+            help='only run specified directives', metavar='DIRECTIVE')
+    parser.add_argument('--except', nargs='+', dest='skip',
+            help='skip specified directives', metavar='DIRECTIVE')
     parser.add_argument('--no-color', dest='no_color', action='store_true',
         help='disable color output')
     parser.add_argument('--version', action='store_true',
@@ -78,7 +82,7 @@ def main():
             # default to directory of config file
             base_directory = os.path.dirname(os.path.abspath(options.config_file))
         os.chdir(base_directory)
-        dispatcher = Dispatcher(base_directory)
+        dispatcher = Dispatcher(base_directory, only=options.only, skip=options.skip)
         success = dispatcher.dispatch(tasks)
         if success:
             log.info('\n==> All tasks executed successfully')

dotbot/dispatcher.py

@@ -4,10 +4,12 @@ from .messenger import Messenger
 from .context import Context
 
 class Dispatcher(object):
-    def __init__(self, base_directory):
+    def __init__(self, base_directory, only=None, skip=None):
         self._log = Messenger()
         self._setup_context(base_directory)
         self._load_plugins()
+        self._only = only
+        self._skip = skip
 
     def _setup_context(self, base_directory):
         path = os.path.abspath(
@@ -20,6 +22,10 @@ class Dispatcher(object):
         success = True
         for task in tasks:
             for action in task:
+                if self._only is not None and action not in self._only \
+                        or self._skip is not None and action in self._skip:
+                    self._log.info('Skipping action %s' % action)
+                    continue
                 handled = False
                 if action == 'defaults':
                     self._context.set_defaults(task[action]) # replace, not update

test/tests/except-multi.bash

@@ -0,0 +1,21 @@
+test_description='--except with multiple arguments'
+. '../test-lib.bash'
+
+test_expect_success 'setup' '
+ln -s ${DOTFILES}/nonexistent ~/bad && touch ${DOTFILES}/y
+'
+
+test_expect_success 'run' '
+run_dotbot --except clean shell <<EOF
+- clean: ["~"]
+- shell:
+  - echo "x" > ~/x
+- link:
+    ~/y: y
+EOF
+'
+
+test_expect_success 'test' '
+[ "$(readlink ~/bad | cut -d/ -f4-)" = "dotfiles/nonexistent" ] &&
+    ! test -f ~/x && test -f ~/y
+'

test/tests/except.bash

@@ -0,0 +1,31 @@
+test_description='--except'
+. '../test-lib.bash'
+
+test_expect_success 'setup' '
+echo "apple" > ${DOTFILES}/x
+'
+
+test_expect_success 'run' '
+run_dotbot --except link <<EOF
+- shell:
+  - echo "pear" > ~/y
+- link:
+    ~/x: x
+EOF
+'
+
+test_expect_success 'test' '
+grep "pear" ~/y && ! test -f ~/x
+'
+
+test_expect_success 'run 2' '
+run_dotbot --except shell <<EOF
+- shell:
+  - echo "pear" > ~/z
+- link:
+    ~/x: x
+'
+
+test_expect_success 'test' '
+grep "apple" ~/x && ! test -f ~/z
+'

test/tests/only-multi.bash

@@ -0,0 +1,20 @@
+test_description='--only with multiple arguments'
+. '../test-lib.bash'
+
+test_expect_success 'setup' '
+ln -s ${DOTFILES}/nonexistent ~/bad && touch ${DOTFILES}/y
+'
+
+test_expect_success 'run' '
+run_dotbot --only clean shell <<EOF
+- clean: ["~"]
+- shell:
+  - echo "x" > ~/x
+- link:
+    ~/y: y
+EOF
+'
+
+test_expect_success 'test' '
+! test -f ~/bad && grep "x" ~/x && ! test -f ~/y
+'

test/tests/only.bash

@@ -0,0 +1,31 @@
+test_description='--only'
+. '../test-lib.bash'
+
+test_expect_success 'setup' '
+echo "apple" > ${DOTFILES}/x
+'
+
+test_expect_success 'run' '
+run_dotbot --only shell <<EOF
+- shell:
+  - echo "pear" > ~/y
+- link:
+    ~/x: x
+EOF
+'
+
+test_expect_success 'test' '
+grep "pear" ~/y && ! test -f ~/x
+'
+
+test_expect_success 'run 2' '
+run_dotbot --only link <<EOF
+- shell:
+  - echo "pear" > ~/z
+- link:
+    ~/x: x
+'
+
+test_expect_success 'test' '
+grep "apple" ~/x && ! test -f ~/z
+'