[Bug-datamash] Re; New feature: extended identifiers

[Assaf Gordon]

Hello Stefan,

Sorry for the delayed response.

regarding your suggestion in:
http://lists.gnu.org/archive/html/bug-datamash/2016-09/msg00006.html

> Now comes in my issue with 'datamash': my dynamically generated
> tables specify column names by the pattern '[a-z0-9-]+', as already
> suggested above. Currently, passing in 'total-node-mem' as a field to
> 'datamash', makes the program to exit with error (saying that field
> ranges must be numeric).

I like this idea, thanks for the patch!

I think this could be made the default, without the need for additional option.
We just need to make it well defined (since quotes are also used for shell 
quoting).

Then we document it, ensure it doesn't cause any regressions with the current 
tests,
and add new tests for this new behavior.

IIUC, you want quotes (single and double) to allow minus characters
(and in fact, any other character?) in a token, which will later be used as a 
field name.

Currently, datamash rejects field names with dashes as:

   $ datamash -H sum total-node-mem
   datamash: field range for ‘sum’ must be numeric

However, simple quotes won't help, as they will be discarded by the shell:

   $ datamash -H sum "total-node-mem"
   datamash: field range for ‘sum’ must be numeric

   $ datamash -H sum 'total-node-mem'
   datamash: field range for ‘sum’ must be numeric

Which means it will either require awkward double quoting:

   $ datamash -H sum "'total-node-mem'"

Or slightly less awkward, with the entire 'program' as a string:

   $ datamash -H "sum 'total-node-mem'"

Both of these are not intuitive (definitely so for less savvy unix users).
It will be tricky to explain this in the documentation,
as saying "use quotes for fields with minus charactesr" is incorrect and 
insufficient,
and then we'll need to go into explaining shell quotes.

Perhaps we should consider another escaping scheme?
one that's easy to type, and does not conflict with other possible shell 
characters?
Something like this (just a thought, not necessarily the optimal solution):

   datamash -H sum {total-node-mem}



regards,
 - assaf