Parse optional short options like gnu getopt

[jridgewell]

Similar to #49, this changes the parsing of optional short options to require no space between the option and argument. Now, -aSomething parse as an option with argument, and -a Something will parse as a present flag with a free non-option.

Note that this only changes optional option arguments (when hasarg = Maybe, as in optflagopt). Required option arguments (when hasarg = Yes, as in optopt) still allow a space between the short option and its argument.

This is a breaking change.

[t-rapp]

As far as I can tell GNU Getopt accepts whitespace between flag and the argument. From the Getopt Manual Example section:

% testopt -c foo
aflag = 0, bflag = 0, cvalue = foo

% testopt -cfoo
aflag = 0, bflag = 0, cvalue = foo

As the non-space-separated variant looks similar to the case where multiple flags are concatenated (i.e. you can write -ab if both -a and -b is defined to as non-argument flags in GNU Getopt) I even prefer using -c foo over -cfoo.

[t-rapp]

On a second thought I recognize that this change is about flags with optional arguments. When I adjust the GNU Getopt example to use a double-colon for the c flag (so the option string becomes "abc::") then C getopt behaves as described in the commit message.

So if this change only affects optional arguments all looks fine for me. The string generated by Options.usage() should be made more clear in this case, though. See #67.

[jridgewell]

Ha, yes, I forgot to put that this is only a change to optional option arguments! optopt will still behave the same, only optflagopt changes.

[KodrAus]

Thanks @jridgewell!