make display_status optional at runtime in setupext

This allow the check_for_readline to *not* print its indented status line

closes gh-361
closes gh-20

setup.py

@@ -62,7 +62,7 b' from setupbase import ('
     check_for_dependencies,
     record_commit_info,
 )
-from setupext.setupext import check_for_readline
+from setupext import setupext
 
 isfile = os.path.isfile
 pjoin = os.path.join
@@ -220,9 +220,10 b" if 'setuptools' in sys.modules:"
         test='nose>=0.10.1',
     )
     requires = setup_args.setdefault('install_requires', [])
-    if not check_for_readline():
+    setupext.display_status = False
+    if not setupext.check_for_readline():
         if sys.platform == 'darwin':
-                requires.append('readline')
+            requires.append('readline')
         elif sys.platform.startswith('win'):
             requires.append('pyreadline')
         else:

setupext/setupext.py

@@ -18,29 +18,35 b' from textwrap import fill'
 
 display_status=True
 
-if display_status:
-    def print_line(char='='):
-        print char * 76
-
-    def print_status(package, status):
-        initial_indent = "%22s: " % package
-        indent = ' ' * 24
-        print fill(str(status), width=76,
-                   initial_indent=initial_indent,
-                   subsequent_indent=indent)
-
-    def print_message(message):
-        indent = ' ' * 24 + "* "
-        print fill(str(message), width=76,
-                   initial_indent=indent,
-                   subsequent_indent=indent)
-
-    def print_raw(section):
-        print section
-else:
-    def print_line(*args, **kwargs):
-        pass
-    print_status = print_message = print_raw = print_line
+def check_display(f):
+    """decorator to allow display methods to be muted by mod.display_status"""
+    def maybe_display(*args, **kwargs):
+        if display_status:
+            return f(*args, **kwargs)
+    return maybe_display
+
+@check_display
+def print_line(char='='):
+    print char * 76
+
+@check_display
+def print_status(package, status):
+    initial_indent = "%22s: " % package
+    indent = ' ' * 24
+    print fill(str(status), width=76,
+               initial_indent=initial_indent,
+               subsequent_indent=indent)
+
+@check_display
+def print_message(message):
+    indent = ' ' * 24 + "* "
+    print fill(str(message), width=76,
+               initial_indent=indent,
+               subsequent_indent=indent)
+
+@check_display
+def print_raw(section):
+    print section
 
 #-------------------------------------------------------------------------------
 # Tests for specific packages