[#370] Updated DisplayCAL.log.SafeLogger.__init__() to properly ini…

…tialize the `print_` arg with `None` and set its default value inside the method, instead of writing a complex expression on the argument itself.

DisplayCAL/log.py

@@ -172,15 +172,15 @@ def write(self, msg):
 
 
 class SafeLogger(SafePrinter):
-    """
-    Print and log safely, avoiding any UnicodeDe-/EncodingErrors on strings
+    """Print and log safely, avoiding any UnicodeDe-/EncodingErrors on strings
     and converting all other objects to safe string representations.
     """
 
-    def __init__(self, log=True, print_=sys.stdout and hasattr(sys.stdout, "isatty") and
-                                        sys.stdout.isatty()):
+    def __init__(self, log=True, print_=None):
         SafePrinter.__init__(self)
         self.log = log
+        if print_ is None:
+            print_ = sys.stdout and hasattr(sys.stdout, "isatty") and sys.stdout.isatty()
         self.print_ = print_
 
     def write(self, *args, **kwargs):