Merge pull request #67 from brettcannon/fix_open

Add an opt-in fixer for open() -> io.open()

Author: takluyver

libmodernize/fixes/__init__.py

@@ -39,4 +39,9 @@
     'libmodernize.fixes.fix_unicode_type',
     'libmodernize.fixes.fix_xrange_six',
     'libmodernize.fixes.fix_zip',
-    ])
+])
+
+# Fixes that are opt-in only.
+opt_in_fix_names = set([
+    'libmodernize.fixes.fix_open',
+])

libmodernize/fixes/fix_open.py

@@ -0,0 +1,18 @@
+from lib2to3 import fixer_base
+from lib2to3.fixer_util import touch_import
+
+
+class FixOpen(fixer_base.ConditionalFix):
+
+    BM_compatible = True
+    order = "pre"
+    skip_on = "io.open"
+
+    PATTERN = """
+    power< 'open' trailer< '(' any+ ')' > >
+    """
+
+    def transform(self, node, results):
+        if self.should_skip(node):
+            return
+        touch_import(u'io', u'open', node)

libmodernize/main.py

@@ -7,7 +7,7 @@
 from lib2to3.main import warn, StdoutRefactoringTool
 from lib2to3 import refactor
 
-from libmodernize.fixes import lib2to3_fix_names, six_fix_names
+from libmodernize.fixes import lib2to3_fix_names, six_fix_names, opt_in_fix_names
 
 
 def main(args=None):
@@ -81,6 +81,7 @@ def main(args=None):
 
     # Initialize the refactoring tool
     unwanted_fixes = set(options.nofix)
+    default_fixes = avail_fixes.difference(opt_in_fix_names)
 
     # Remove unicode fixers depending on command line options
     if options.six_unicode:
@@ -101,9 +102,9 @@ def main(args=None):
                 all_present = True
             else:
                 explicit.add(fix)
-        requested = avail_fixes.union(explicit) if all_present else explicit
+        requested = default_fixes.union(explicit) if all_present else explicit
     else:
-        requested = avail_fixes.union(explicit)
+        requested = default_fixes
     fixer_names = requested.difference(unwanted_fixes)
     rt = StdoutRefactoringTool(sorted(fixer_names), flags, sorted(explicit),
                                options.nobackups, not options.no_diffs)
@@ -118,7 +119,7 @@ def main(args=None):
                             options.processes)
             except refactor.MultiprocessingUnsupported:
                 assert options.processes > 1
-                print("Sorry, -j isn't supported on this platform.", 
+                print("Sorry, -j isn't supported on this platform.",
                       file=sys.stderr)
                 return 1
         rt.summarize()

tests/test_fix_open.py

@@ -0,0 +1,16 @@
+from utils import check_on_input
+
+
+OPEN = ("""\
+open('some/path')
+""", """\
+from io import open
+open('some/path')
+""")
+
+
+def test_open():
+    check_on_input(*OPEN, extra_flags=['-f', 'libmodernize.fixes.fix_open'])
+
+def test_open_optional():
+    check_on_input(OPEN[0], OPEN[0])