Added env variable way to output to stdout and autocheck for Jupyter

README.md

@@ -230,6 +230,8 @@ except ImportError:  # Graceful fallback if IceCream isn't installed.
 
 ### Configuration
 
+By default, icecream will output to stderr unless the environment variable `PYTHON_ICECREAM_USE_STDOUT ` is true (i.e. if it case insensitively matches `1`, `y`, `yes`, `t` or `true`). It will also switch to the stdout if running inside Jupyter.
+
 `ic.configureOutput(prefix, outputFunction, argToStringFunction,
 includeContext)` can be used to adopt a custom output prefix (the default is
 `ic| `), change the output function (default is to write to stderr), customize

icecream/icecream.py

@@ -11,8 +11,10 @@
 # License: MIT
 #
 
+
 from __future__ import print_function
 
+import os
 import ast
 import inspect
 import pprint
@@ -63,9 +65,8 @@ def supportTerminalColorsInWindows():
     yield
     colorama.deinit()
 
-
-def stderrPrint(*args):
-    print(*args, file=sys.stderr)
+def ICFilePrint(*args):
+    print(*args, file=DEFAULT_OUTPUT_FILE)
 
 
 def isLiteral(s):
@@ -76,18 +77,27 @@ def isLiteral(s):
     return True
 
 
-def colorizedStderrPrint(s):
+def colorizedICFilePrint(s):
     colored = colorize(s)
     with supportTerminalColorsInWindows():
-        stderrPrint(colored)
+        ICFilePrint(colored)
 
 
 DEFAULT_PREFIX = 'ic| '
 DEFAULT_LINE_WRAP_WIDTH = 70  # Characters.
 DEFAULT_CONTEXT_DELIMITER = '- '
-DEFAULT_OUTPUT_FUNCTION = colorizedStderrPrint
+DEFAULT_OUTPUT_FUNCTION = colorizedICFilePrint
 DEFAULT_ARG_TO_STRING_FUNCTION = pprint.pformat
 
+def str2bool(v):
+    return str(v).lower() in ["yes", "true", "t", "1", "y"]
+
+def is_in_jupyter():
+    try:
+        from IPython import get_ipython
+        return get_ipython() is not None
+    except ModuleNotFoundError:
+        return False
 
 class NoSourceAvailableError(OSError):
     """
@@ -329,5 +339,14 @@ def configureOutput(self, prefix=_absent, outputFunction=_absent,
         if includeContext is not _absent:
             self.includeContext = includeContext
 
+def reload():
+    global ic, DEFAULT_OUTPUT_FILE
+
+    if is_in_jupyter() or str2bool(os.environ.get('PYTHON_ICECREAM_USE_STDOUT')):
+        DEFAULT_OUTPUT_FILE = sys.stdout
+    else:
+        DEFAULT_OUTPUT_FILE = sys.stderr
+
+    ic = IceCreamDebugger()
 
-ic = IceCreamDebugger()
+reload()

tests/test_icecream.py

@@ -19,9 +19,12 @@
 from contextlib import contextmanager
 from os.path import basename, splitext
 
+import os
 import icecream
-from icecream import ic, stderrPrint, NoSourceAvailableError
+from icecream import ic, ICFilePrint, NoSourceAvailableError
 
+# Ensure our tests don't fail because of a misconfigured environment
+os.environ['PYTHON_ICECREAM_USE_STDOUT'] = 'False'
 
 TEST_PAIR_DELIMITER = '| '
 MYFILENAME = basename(__file__)
@@ -54,7 +57,7 @@ def isatty(self):
 def disableColoring():
     originalOutputFunction = ic.outputFunction
 
-    ic.configureOutput(outputFunction=stderrPrint)
+    ic.configureOutput(outputFunction=ICFilePrint)
     yield
     ic.configureOutput(outputFunction=originalOutputFunction)
 
@@ -92,8 +95,10 @@ def captureStandardStreams():
     try:
         sys.stdout = newStdout
         sys.stderr = newStderr
+        icecream.reload()
         yield newStdout, newStderr
     finally:
+        icecream.reload()
         sys.stdout = realStdout
         sys.stderr = realStderr
 
@@ -302,7 +307,7 @@ def testDifferentName(self):
 
     def testPrefixConfiguration(self):
         prefix = 'lolsup '
-        with configureIcecreamOutput(prefix, stderrPrint):
+        with configureIcecreamOutput(prefix, ICFilePrint):
             with disableColoring(), captureStandardStreams() as (out, err):
                 ic(a)
         pair = parseOutputIntoPairs(out, err, 1, prefix=prefix)[0][0]