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Re: [ddlm-group] Interactions with methods


Nick Spadaccini wrote:

On 11/09/09 10:39 PM, "David Brown" <idbrown@mcmaster.ca> wrote:

I am glad that this point is made clear as it colours my thinking when
preparing the dictionary.  I am glad to have some guidelines to decide which
methods should be included.  I still wonder, though, whether it would be
useful to include in the methods loop an item _methods_description which would
be a short text description that could be used by an application to log the
progress of a calculation.  The problem is that the applcation has no way of
knowing what it is calculating apart from the dataname of the object it is
attempting to calculate.  This could be picked up by the application to
produce a message such as :

'Unable to calculate _refln.F_squared_calc using _refln.F_calc'

This might be satisfactory for trouble shooting, but if the writer of the
application wanted to put out a more user-friendly message, he might prefer to
have available a description such as:
Two ways. Comments within the dREL code, or a separate description data
item. Probably both in real day to day use.
I will introduce an item into the methods loops of the CIFm dictionaries as follows:

# _method.description  'descriptive text...'

When the item _method.description becomes an approved DDLm dataname I will remove the #

 'Calculation of F(calc)^2 from F(calc) failed'

using the item 

 _methods_description   'Calculation of F(calc)^2 from F(calc)'

This does not affect the structure of DDLm or the dictionaries, but does give
the writer of an application another handle.
Easy to do. That would just be a print statement from within the dREL code
that calculates Fc^2 from Fc.
Printing the dREL code would be OK for trouble shooting, but would not be particlarly  friendly for, say, an interactive message to a user unfamilier with the dictionaries and dREL constructs.  However, the writer of the application can decide which information is best for a particular output.



Associate Professor N. Spadaccini, PhD
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