[GRASS-dev] python parser question

GRASS GRASS developer
1

Hi,

the python version of m.proj in trunk now has:

#%option
#% key: fs
#% type: string
#% description: Field separator (format: input,output)
#% required : no
#% key_desc : character,character
#% answer : |,|
#%end

Question:
if the fs is a comma (.csv), won't that come to grief here:
    #### parse field separator
    ifs, ofs = fs.split(',')

I find the current way to be too much typing. could it be like
#% answer : input_fs[,output_fs]

so most of the time you don't need a,b? (if b==NULL then b=a)

(AFAIR the parser does special "2 input options required" checks
if you use opt->key_desc="a,b")

or is fs_in= and fs_out= needed to please both the parser and the python?

or do we need a new
    elif ifs.lower() == "comma":
(I'd rather avoid that)

thanks,
Hamish

2

Hamish wrote:

the python version of m.proj in trunk now has:

#%option
#% key: fs
#% type: string
#% description: Field separator (format: input,output)
#% required : no
#% key_desc : character,character
#% answer : |,|
#%end

You need "multiple: yes" in order to use key_desc this way (i.e. check
that answers are in the correct multiples). Otherwise, key_desc is
merely a string which is used in the help text, HTML/XML output, etc.

Question:
if the fs is a comma (.csv), won't that come to grief here:
    #### parse field separator
    ifs, ofs = fs.split(',')

Yes.

[With "multiple: yes", it will come to grief before that, in g.parser.
If you have opt->multiple == YES, there is no way for an answer to
include a comma.]

I find the current way to be too much typing. could it be like
#% answer : input_fs[,output_fs]

so most of the time you don't need a,b? (if b==NULL then b=a)

(AFAIR the parser does special "2 input options required" checks
if you use opt->key_desc="a,b")

Only for "multiple" options.

or is fs_in= and fs_out= needed to please both the parser and the python?

Nothing stops you having fs=<string>, but nothing will check the
format of the string; e.g. the GUI won't stop you doing fs=a,b,c,d.

or do we need a new
    elif ifs.lower() == "comma":
(I'd rather avoid that)

Yes. Well, if you're going to use a comma to separate the input and
output separators, you need to provide some way to specify a literal
comma.

--
Glynn Clements <glynn@gclements.plus.com>

3

Hi,

2009/5/13 Hamish <hamish_b@yahoo.com>:

[...]

so most of the time you don't need a,b? (if b==NULL then b=a)

(AFAIR the parser does special "2 input options required" checks
if you use opt->key_desc="a,b")

or is fs_in= and fs_out= needed to please both the parser and the python?

I prefer to avoid separate options for input/output field separator.

or do we need a new
elif ifs.lower() == "comma":
(I'd rather avoid that)

I hope better in r37277.

Martin

--
Martin Landa <landa.martin gmail.com> * http://gama.fsv.cvut.cz/~landa