Can Miller hook a user up with an error message about (accidentally) using named fields with '--nidx' and similar options?

[ernstki]

Hi all,

Yes, I'll preface this by saying this is definitely an "operator error" that can be resolved with experience, or a careful review of the documentation.

However, would it not be beneficial to everyone to see an error message when you try to specify obviously non-numeric fields with --nidx and -T (and related) options when using verbs like nest and cut that have a -f option?

For example, if you mistakenly use -T when you meant --tsv, this doesn't seem to work right:

echo -e "last_first\nLastName, Firstname" \
  | mlr -T cut -f last_first

# result:
# (a couple of blank lines)

Of course this does:

echo -e "last_first\nLastName, Firstname" \
  | mlr -T cut -f 1

# result:
# last_first
# LastName, Firstname

…and so, obviously, would mlr --tsv cut -f last_first.

But ideally, the first case would error out, telling the user "Hey, you know you tried to specify a named field when the input format was numerically indexed, right?"

[johnkerl]

@ernstki thanks, this is a great idea! :)