[GRASS-dev] Re: [GRASS-CVS] carlos: grass6/raster/r.his main.c, 2.6, 2.7

[Paul Kelly]

On Fri, 6 Jul 2007, Brad Douglas wrote:

> On Fri, 2007-07-06 at 14:33 +0200, Martin Landa wrote:
>> Ciao Carlos,
>>
>> I am not sure too (it is the question for native speakers...)
>>
>> http://www.nabble.com/message-standardization-on-wiki-tf3559274.html#a9939189
>>
>> "Cannot open raster map" X "Unable to open raster map"
>
> There is no issue with tense here.
>
> I prefer "Unable to".  It's negative without being so forcefully
> negative (if that makes any sense).  Either will work, but I believe
> there are fewer cases of "Cannot..." than "Unable to..." in source.

I'm just replying to make the point how there really seems to be no 
difference between the two forms: I disagree with the above and feel 
"unable to" sounds much more harsh and formal than "can not", "cannot" or 
"can't", which IMHO correspond more with every day speech. But perhaps 
there is a American/European English difference here. In which case given 
GRASS's roots the American is probably the way to go I guess? Are there 
any languages into which, when translated, the two phrases mean something 
substantially different?

In any case I think it is clearer if error messages like these (resulting 
from filesystem errors) are augmented where possible with the system error 
message from strerror(errno()) - see e.g. in lib/gis/copy_file.c:
         G_warning( "Cannot open %s for reading: %s", infile,
                    strerror(errno) );

Here's a thought - to me, "unable to" suggests that the reason why 
something could not be done is outside GRASS's control, and perhaps would 
suit the above example from G_copy_file() better than "cannot" as the 
reason (the system error message) is presented after the GRASS error. 
Whereas perhaps "cannot" suggests that's simply all there is to it and 
the program is unable to go into any more depth on what caused the error.
i.e.
"unable to": error/warning caused by something outside GRASS; say what it 
is
"cannot": error/warning is something within GRASS that genuinely isn't 
possible.
But I'm really splitting hairs here, trying to justify why we have the two 
forms in GRASS. But perhaps it isn't possible to justify that...

Paul