support for "+=" field separator?

[vicenteg]

I get an error when parsing a hocon file:

[ec2-user@ip-172-16-2-117 ~]$ pyhocon -i /opt/mapr/drill/drill-1.1.0/conf/drill-override-example.conf
Traceback (most recent call last):
  File "/usr/local/bin/pyhocon", line 9, in <module>
    load_entry_point('pyhocon==0.3.4', 'console_scripts', 'pyhocon')()
  File "/usr/local/lib/python2.7/site-packages/pyhocon/tool.py", line 188, in main
    HOCONConverter.convert(args.input, args.output, args.format)
  File "/usr/local/lib/python2.7/site-packages/pyhocon/tool.py", line 145, in convert
    config = ConfigFactory.parse_file(input_file)
  File "/usr/local/lib/python2.7/site-packages/pyhocon/__init__.py", line 40, in parse_file
    return ConfigFactory.parse_string(content, os.path.dirname(filename))
  File "/usr/local/lib/python2.7/site-packages/pyhocon/__init__.py", line 75, in parse_string
    return ConfigParser().parse(content, basedir)
  File "/usr/local/lib/python2.7/site-packages/pyhocon/__init__.py", line 216, in parse
    config = config_expr.parseString(content, parseAll=True)[0]
  File "/usr/local/lib/python2.7/site-packages/pyparsing.py", line 1125, in parseString
    raise exc
pyparsing.ParseSyntaxException: Expected "{" (at char 1087), (line:20, col:33)

Line 20 in the above looks like this:

drill.logical.function.packages += "org.apache.drill.exec.expr.fn.impl"

And column 33 implicates the "+=" field separator.

Any plans to add support for this?
https://github.com/typesafehub/config/blob/master/HOCON.md#the--field-separator

[akumarpatel]

It seems like the self referencing does not work with Pyhocon . Following cases does not work

1. Examples of self-referential fields:
   a : ${a}
   a : ${a}bc
   path : ${path} [ /usr/bin ]
2. a += b
   becomes:

a = ${?a} [b]

[alexey-terentiev]

I'm eager to have self-referencing feature too.

[maxharp3r]

Yay, thanks! Although, the fix requires a workaround in my case where I am not using top-level properties. This now works:

a.b {
    c += "foo"
}

These still do not work, and throw different exceptions:

a.b.c += "foo"
a.b.c = ${?a.b.c} ["foo"]