bmaptools/CLI.py: Print help in case of no arguments

[lsandov1]

This fix avoids the following run-time exception:

$ bmaptool
Traceback (most recent call last):
  File "/usr/bin/bmaptool", line 11, in <module>
    load_entry_point('bmap-tools==3.4', 'console_scripts', 'bmaptool')()
  File "/usr/lib/python3.6/site-packages/bmaptools/CLI.py", line 715, in main
    args.func(args)
AttributeError: 'Namespace' object has no attribute 'func'

[kad]

I'm curious, in which environment you got such traceback ? and how it was installed ?

[codecov-io]

Codecov Report

Merging #51 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master     #51   +/-   ##
======================================
  Coverage    67.7%   67.7%           
======================================
  Files           5       5           
  Lines        1025    1025           
======================================
  Hits          694     694           
  Misses        331     331

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[icarus-sparry]

@kad We see this in both debian and clear linux, the former with the standard repository. The reproduction step is just to invoke {code}bmaptool{code} without any arguments. If you give it an argument then it prints out a help message if you do not give it one of the two required subcommands.

[lsandov1]

Clear Linux OS and the installation is done through https://github.com/clearlinux-pkgs/bmap-tools

[smcv]

This seems to be a behaviour change in Python 3:

$ python2 ./bmaptool
usage: bmaptool [-h] [--version] [-q] [-d] {create,copy} ...
bmaptool: error: too few arguments
$ python3 ./bmaptool
Traceback (most recent call last):
  File "./bmaptool", line 11, in <module>
    sys.exit(main())
  File "/home/smcv/src/debian/bmap-tools/bmaptools/CLI.py", line 715, in main
    args.func(args)
AttributeError: 'Namespace' object has no attribute 'func'

[smcv]

See also python/cpython#3027, python/cpython#6919.

[smcv]

This might be a nicer way to do the same thing?

diff --git a/bmaptools/CLI.py b/bmaptools/CLI.py
index 09b23af..cad4173 100644
--- a/bmaptools/CLI.py
+++ b/bmaptools/CLI.py
@@ -636,7 +636,12 @@ def parse_arguments():
     text = "do not verify the data checksum while writing"
     parser_copy.add_argument("--no-verify", action="store_true", help=text)
 
-    return parser.parse_args()
+    args = parser.parse_args()
+
+    if not hasattr(args, 'func'):
+        parser.error('too few arguments')
+
+    return args
 
 
 def setup_logger(loglevel):

[smcv]

Or even:

diff --git a/bmaptools/CLI.py b/bmaptools/CLI.py
index 09b23af..eb694e1 100644
--- a/bmaptools/CLI.py
+++ b/bmaptools/CLI.py
@@ -579,7 +579,8 @@ def parse_arguments():
     text = "print debugging information"
     parser.add_argument("-d", "--debug", action="store_true", help=text)
 
-    subparsers = parser.add_subparsers(title="commands")
+    subparsers = parser.add_subparsers(title="commands", dest="command")
+    subparsers.required = True
 
     #
     # Create parser for the "create" command

[lsandov1]

Right, your approach is better

[lsandov1]

I will send a v2.