[diffoscope] 04/05: Refactor Presenter to a singleton manager

[Chris Lamb]

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lamby pushed a commit to branch experimental
in repository diffoscope.

commit 1e8c1f637c53ee041d305f4a6e256e43e202173d
Author: Chris Lamb <lamby at debian.org>
Date:   Sun Apr 30 09:25:39 2017 +0100

    Refactor Presenter to a singleton manager
    
    Signed-off-by: Chris Lamb <lamby at debian.org>
---
 diffoscope/main.py               |  11 ++--
 diffoscope/presenters/formats.py | 123 +++++++++++++++++++++++----------------
 2 files changed, 78 insertions(+), 56 deletions(-)

diff --git a/diffoscope/main.py b/diffoscope/main.py
index caa824a..231b3e0 100644
--- a/diffoscope/main.py
+++ b/diffoscope/main.py
@@ -40,7 +40,7 @@ from .difference import Difference
 from .comparators import ComparatorManager
 from .external_tools import EXTERNAL_TOOLS
 from .presenters.html import JQUERY_SYSTEM_LOCATIONS
-from .presenters.formats import configure_presenters, output_all
+from .presenters.formats import PresenterManager
 from .comparators.utils.compare import compare_root_paths
 
 logger = logging.getLogger(__name__)
@@ -271,6 +271,7 @@ def maybe_set_limit(config, parsed_args, key):
 def run_diffoscope(parsed_args):
     setup_logging(parsed_args.debug)
     ProfileManager().setup(parsed_args)
+    PresenterManager().configure(parsed_args)
     logger.debug("Starting diffoscope %s", VERSION)
     if not tlsh and Config().fuzzy_threshold != parsed_args.fuzzy_threshold:
         logger.warning('Fuzzy-matching is currently disabled as the "tlsh" module is unavailable.')
@@ -285,11 +286,7 @@ def run_diffoscope(parsed_args):
     Config().fuzzy_threshold = parsed_args.fuzzy_threshold
     Config().new_file = parsed_args.new_file
     Config().excludes = parsed_args.excludes
-    presenter_config = configure_presenters(parsed_args)
-    # Don't waste time computing visual differences if we won't use them.
-    Config().compute_visual_diffs = any(
-        x['klass'].supports_visual_diffs for x in presenter_config.values(),
-    )
+    Config().compute_visual_diffs = PresenterManager().compute_visual_diffs()
     set_path()
     set_locale()
     logger.debug('Starting comparison')
@@ -304,7 +301,7 @@ def run_diffoscope(parsed_args):
     if difference is None and parsed_args.output_empty:
         difference = Difference(None, parsed_args.path1, parsed_args.path2)
     with profile('main', 'outputs'):
-        output_all(presenter_config, difference, parsed_args, has_differences)
+        PresenterManager().output(difference, parsed_args, has_differences)
     return 1 if has_differences else 0
 
 
diff --git a/diffoscope/presenters/formats.py b/diffoscope/presenters/formats.py
index e30ac8e..94b723f 100644
--- a/diffoscope/presenters/formats.py
+++ b/diffoscope/presenters/formats.py
@@ -17,7 +17,6 @@
 # You should have received a copy of the GNU General Public License
 # along with diffoscope.  If not, see <https://www.gnu.org/licenses/>.
 
-import sys
 import logging
 
 from ..profiling import profile
@@ -31,51 +30,77 @@ from .restructuredtext import RestructuredTextPresenter
 logger = logging.getLogger(__name__)
 
 
-def configure_presenters(parsed_args):
-    FORMATS = {
-        'text': {
-            'klass': TextPresenter,
-            'target': parsed_args.text_output,
-        },
-        'html': {
-            'klass': HTMLPresenter,
-            'target': parsed_args.html_output,
-        },
-        'json': {
-            'klass': JSONPresenter,
-            'target': parsed_args.json_output,
-        },
-        'markdown': {
-            'klass': MarkdownTextPresenter,
-            'target': parsed_args.markdown_output,
-        },
-        'restructuredtext': {
-            'klass': RestructuredTextPresenter,
-            'target': parsed_args.restructuredtext_output,
-        },
-        'html_directory': {
-            'klass': HTMLDirectoryPresenter,
-            'target': parsed_args.html_output_directory,
-        },
-    }
-
-    result = {k: v for k, v in FORMATS.items() if v['target'] is not None}
-
-    # If no output specified, default to printing --text output to stdout
-    if not result:
-        parsed_args.text_output = FORMATS['text']['target'] = '-'
-        result['text'] = FORMATS['text']
-
-    logger.debug(
-        "Will generate the following formats: %s", ", ".join(result.keys()),
-    )
-
-    return result
-
-
-def output_all(config, difference, parsed_args, has_differences):
-    for name, data in config.items():
-        logger.debug("Generating %r output at %r", name, data['target'])
-
-        with profile('output', name):
-            data['klass'].run(data, difference, parsed_args, has_differences)
+class PresenterManager(object):
+    _singleton = {}
+
+    def __init__(self):
+        self.__dict__ = self._singleton
+
+        if not self._singleton:
+            self.reset()
+
+    def reset(self):
+        self.config = {}
+
+    def configure(self, parsed_args):
+        FORMATS = {
+            'text': {
+                'klass': TextPresenter,
+                'target': parsed_args.text_output,
+            },
+            'html': {
+                'klass': HTMLPresenter,
+                'target': parsed_args.html_output,
+            },
+            'json': {
+                'klass': JSONPresenter,
+                'target': parsed_args.json_output,
+            },
+            'markdown': {
+                'klass': MarkdownTextPresenter,
+                'target': parsed_args.markdown_output,
+            },
+            'restructuredtext': {
+                'klass': RestructuredTextPresenter,
+                'target': parsed_args.restructuredtext_output,
+            },
+            'html_directory': {
+                'klass': HTMLDirectoryPresenter,
+                'target': parsed_args.html_output_directory,
+            },
+        }
+
+        self.config = {
+            k: v for k, v in FORMATS.items() if v['target'] is not None
+        }
+
+        # If no output specified, default to printing --text output to stdout
+        if not self.config:
+            parsed_args.text_output = FORMATS['text']['target'] = '-'
+            self.config['text'] = FORMATS['text']
+
+        logger.debug(
+            "Will generate the following formats: %s",
+            ", ".join(self.config.keys()),
+        )
+
+    def output(self, difference, parsed_args, has_differences):
+        for name, data in self.config.items():
+            logger.debug("Generating %r output at %r", name, data['target'])
+
+            with profile('output', name):
+                data['klass'].run(
+                    data,
+                    difference,
+                    parsed_args,
+                    has_differences,
+                )
+
+    def compute_visual_diffs(self):
+        """
+        Don't waste time computing visual differences if we won't use them.
+        """
+
+        return any(
+            x['klass'].supports_visual_diffs for x in self.config.values(),
+        )

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