optparse 1.6.6

Throws an error for unknown short flags and long flags when positional_arguments=TRUE. Thanks Greg Minshall for bug report (#34).
If the callback parameter of add_option / make_option is not NULL then the default of action is now "callback". Thanks Greg Minshall for suggestion (#35).
Better documentation of action=="callback" in the man page for add_option and make_option. Thanks Greg Minshall for bug report (#35).

optparse 1.6.4

Fixes bug in printing help for action=="callback" when metavar==NULL (#29). Thanks Ni Huang for bug report.
Throws an error when passed short flags more than one letter long (#32). Thanks Gautier Richard for bug report.

Fixs a parsing bug when action=="callback" and positional_argument==TRUE (#28). Thanks Ni Huang for bug report.

Supports callback actions (#26). Thanks Gyu Jin Choi for patch.
If interactive() == FALSE and print_help_and_exit == TRUE then optparse will now call quit(status=0) instead of quit(status=1) after printing the help message (this matches behaviour of the python package).
Better error message when forgetting to set add_help_option=FALSE when defining an -h or --help flag. Thanks Jeff P. Bruce for bug report.
Increment getopt requirement so that empty strings are parsed correctly. Thanks Matthew Flickinger for bug report.

Minor documentation fixes. Thanks J. J. Ramsey and Daeyoung Kim for bug reports.
Fix bug when add_help_option in OptionParser set to FALSE. Thanks to Jeff Bruce for bug report.
parse_args now supports convert_hyphens_to_underscores argument which converts any hyphens to underscores when returning the list of options
Now includes the convenience function parse_args2 which wraps parse_args with positional_arguments set to TRUE and convert_hyphens_to_underscores set to TRUE.

optparse should no longer give any warnings when options(warnPartialMatchArgs=TRUE). Thanks Rich FitzJohn for patch.
print_help no longer throws an error if we have a default argument of length zero. Thanks Benjamin Tyner for bug report.

OptionParser and OptionParserOption S4 classes are now exported. Thanks Peter Humburg for patch.

Parameter positional_arguments of function parse_args now accepts one or two numeric values that denote the minimum and maximum number of supported positional arguments. Thanks Kirill Müller for patch.
If interactive() == TRUE then parse_args will no longer quit(status=1) after printing a help message but will instead throw an error. optparse will continue to quit(status=1) after printing a help message for non-interactive Rscripts unless print_help_and_exit == FALSE.
In make_option argument type="numeric" automatically cast to double. Previously users might have received an error passing negative numbers if they accidentally specified “numeric” instead of “double”.
Bug fixed in printing usage message for options with default value of NA and a help string including “%default”. Thanks Stefan Seemayer for bug report and patch.

Project website moved to https://github.com/trevorld/optparse
We now replace all occurrences of %prog in usage message (including description and epilogue). Previously we would only replace one occurrence and didn’t make replacements in description and epilogue.
Fix bug in parse_args when we have options with no short flag and positional_arguments=TRUE. Thanks Miroslav Posta for bug report.

Added description and epilogue arguments to OptionParser to allow users to add more information to generated help messages
Slightly alters the generated usage string to match more closely what the Python module does
No longer exports S4 classes that represent OptionParser and OptionParserOption
Now requires package getopt (>= 1.19) which has also been moved to Imports field from Depends field in DESCRIPTION
Now also Suggests stringr package in DESCRIPTION