[GRASS-dev] Help text for r.stats

Vaclav Petras wenzeslaus at gmail.com
Tue Aug 7 20:35:10 PDT 2018

On Tue, Aug 7, 2018 at 10:44 PM, Nikos Alexandris <nik at nikosalexandris.net>

> Vaclav:
>> That being said, this is not set in stone. For example, some modules could
>> benefit from something like formalized "suggested values" as opposed to
>> "the only allowed values", but "suggested values" is still not the same as
>> "special characters" here or generally "specially treated values".
> Maybe I am over-thinking about it: is it wrong to allow _all_ characters
> being used as separators except of the set of characters that have a
> special meaning to the underlying OSes or else would cause any sorts of
> problems?

This comment was really general, not necessarily related to field
separators in text files. Anyway, the problem with separators is really to
have the separator in the command line written without any escaping or
quoting. To avoid thinking about when and how to do it, we provide these
special values such as "pipe" which are the replaced by the corresponding
character (but themselves are completely safe/harmless). Additionally,
these special characters are good for readability `separator=,` or `,
separator=',', in Python` look little strange and whitespace characters may
suffer from combination of both. Of course then there is the problem with
conflict with characters in the file. Comma as separator and comma as
"decimal point" would be the typical example from Czech environment. How we
avoid that is that we let user to decide on the separator and we are using
pipe as a default since it is an unusual character in text (but also quite
know and visually appropriate at the same time if you are dealing with
command line).

> Then, describe this like "Supported characters are only..." or "All
> characters supported except of ..."?

Disallowing characters is not really desired for the separator, but
generally the "only supported characters/values" behavior is what the
options item is doing. The "all values except these" behavior, basically a
negation of the options item is something we don't have in the parser (but
we probably don't have any use of it either at this point).

> Great answer Vaclav!

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