Have load_config() and write_(min_)config() return messages

Hardcoding load_config() and write_(min_)config() to write any message
to stdout is awkward, because it means that the message can't be easily
reused when stdout is the wrong place to write it to (e.g. in
menuconfig/guiconfig). This gets extra bad now that there's also the "No
change to ..." message.

Modify load_config() and write_(min_)config() to return the message as a
string instead, and have them always return a message, instead of just
when 'filename' is None and verbose=True. This makes things flexible and
straightforward.

Use the new behavior in menuconfig.py and guiconfig.py. They now show
"No change to ..." when saving a file doesn't modify it.

Tools that want to write messages to stdout should now do
print(kconf.load_config()) / print(kconf.write_config()).

There's no clean way to preserve perfect backwards compatibility here,
but keep accepting the 'verbose' argument and print a deprecation
warning if a value is ever passed for it. That way, scripts will keep
running, though possibly with less output on stdout.

This changes the meaning of the load_config() return value as well,
though I suspect it was only ever used by the menuconfig/guiconfig
interfaces.

The new behavior applies for kconfiglib.VERSION >= (12, 0, 0).

1 files changed, 11 insertions, 13 deletions

diff --git a/examples/menuconfig_example.py b/examples/menuconfig_example.py
index 4e2560d..b265e69 100644..100755
--- a/examples/menuconfig_example.py
+++ b/examples/menuconfig_example.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python
+
 # Implements a simple configuration interface on top of Kconfiglib to
 # demonstrate concepts for building a menuconfig-like. Emulates how the
 # standard menuconfig prints menu entries.
@@ -117,6 +119,7 @@
 #
 #   Enter a symbol/choice name, "load_config", or "write_config" (or press CTRL+D to exit): ^D
 
+from __future__ import print_function
 import readline
 import sys
 
@@ -300,27 +303,22 @@ if __name__ == "__main__":
 
         if cmd == "load_config":
             config_filename = input(".config file to load: ")
-
             try:
-                kconf.load_config(config_filename)
+                # Returns a message telling which file got loaded
+                print(kconf.load_config(config_filename))
             except IOError as e:
-                # Print the (spammy) error from Kconfiglib itself
-                print(e.message + "\n")
-            else:
-                print("Configuration loaded from " + config_filename)
+                print(e, file=sys.stderr)
 
             print_menuconfig(kconf)
             continue
 
         if cmd == "write_config":
             config_filename = input("To this file: ")
-
             try:
-                kconf.write_config(config_filename)
+                # Returns a message telling which file got saved
+                print(kconf.write_config(config_filename))
             except IOError as e:
-                print(e.message)
-            else:
-                print("Configuration written to " + config_filename)
+                print(e, file=sys.stderr)
 
             continue
 
@@ -340,5 +338,5 @@ if __name__ == "__main__":
 
             continue
 
-        print("No symbol/choice named '{}' in the configuration"
-              .format(cmd))
+        print("No symbol/choice named '{}' in the configuration".format(cmd),
+              file=sys.stderr)