added option to force color output, even if not a tty

src/rez/config.py

@@ -126,6 +126,7 @@ class Bool(Setting):
     schema = Schema(bool)
     true_words = frozenset(["1", "true", "yes", "y", "on"])
     false_words = frozenset(["0", "false", "no", "n", "off"])
+    all_words = true_words | false_words
 
     def _parse_env_var(self, value):
         value = value.lower()
@@ -134,10 +135,22 @@ def _parse_env_var(self, value):
         elif value in self.false_words:
             return False
         else:
-            words = self.true_words | self.false_words
             raise ConfigurationError(
                 "expected $%s to be one of: %s"
-                % (self._env_var_name, ", ".join(words)))
+                % (self._env_var_name, ", ".join(self.all_words)))
+
+
+class ForceOrBool(Bool):
+    FORCE_STR = "force"
+
+    # need force first, or Bool.schema will coerce "force" to True
+    schema = Or(FORCE_STR, Bool.schema)
+    all_words = Bool.all_words | frozenset([FORCE_STR])
+
+    def _parse_env_var(self, value):
+        if value == self.FORCE_STR:
+            return value
+        super(ForceOrBool, self)._parse_env_var(value)
 
 
 class Dict(Setting):
@@ -272,7 +285,7 @@ def _parse_env_var(self, value):
     "memcached_resolve_min_compress_len":           Int,
     "allow_unversioned_packages":                   Bool,
     "rxt_as_yaml":                                  Bool,
-    "color_enabled":                                Bool,
+    "color_enabled":                                ForceOrBool,
     "resolve_caching":                              Bool,
     "cache_package_files":                          Bool,
     "cache_listdir":                                Bool,

src/rez/rezconfig.py

@@ -586,6 +586,11 @@
 # Enables/disables colorization globally.
 # Note: Turned off for Windows currently as there seems to be a problem with
 # the Colorama module.
+# May also set to the string "force", which will make rez output color styling
+# information, even if the the output streams are not ttys. Useful if you are
+# piping the output of rez, but will eventually be printing to a tty later.
+# When force is used, will generally be set through an environemnt variable, ie,
+#    echo $(REZ_COLOR_ENABLED=force python -c "from rez.utils.colorize import Printer, local; Printer()('foo', local)")
 color_enabled = (os.name == "posix")
 
 ### Do not move or delete this comment (__DOC_END__)

src/rez/utils/colorize.py

@@ -258,6 +258,10 @@ def is_tty(self):
         """
         return stream_is_tty(self.stream)
 
+    @property
+    def is_colorized(self):
+        return config.get("color_enabled", False) == "force" or self.is_tty
+
     def _get_style_function_for_level(self, level):
         return self.STYLES.get(level, notset)
 
@@ -271,7 +275,7 @@ def emit(self, record):
         try:
             message = self.format(record)
 
-            if not self.is_tty:
+            if not self.is_colorized:
                 self.stream.write(message)
             else:
                 style = self._get_style_function_for_level(record.levelno)
@@ -289,13 +293,14 @@ def emit(self, record):
 class Printer(object):
     def __init__(self, buf=sys.stdout):
         self.buf = buf
-        self.tty = stream_is_tty(buf)
+        self.colorize = (config.get("color_enabled", False) == "force") \
+                        or stream_is_tty(buf)
 
     def __call__(self, msg='', style=None):
         print >> self.buf, self.get(msg, style)
 
     def get(self, msg, style=None):
-        if style and self.tty:
+        if style and self.colorize:
             msg = style(msg)
         return msg