[QUANTITY] doc consistency

[Patrick Dowler]

On Wednesday 19 May 2004 09:46, Pierre Didelon wrote:
> It would be nice to materialise the serialization possibility
> of quantity by a method, appearing in clase Frame or BasicQuantity.
> Moreover it would be nice if this "serialize" method could have a
> calling param
> to choose the output format, this one could perhaps be pure_xml,
> VOTable,
> ASCII, Fits, SQL Statements... or whatever needed or required,
> incrementally,
> starting implementation of the most obvious one, which would be
> the default format, if the required one by user is unavailable
> Something like getSerialization(format: string): string

The problem with this is that  -as others have pointed out - it ties the code 
you write to the serialisations explicitly. This is an even worse thing to do 
at the interface level....

The early days of XML saw object models (DOMs) with methods like

String toXML() { ... }

but that style has since been dropped in more recent years as it was very 
brittle. Now, designers favour an object model and a separate serialisation 
tool(s). In java that might be a QuantityReader/QuantityWriter pair using the 
standard way to name such things), and then you just pick a suitable reader 
or writer that does the format you desire. 

There are really no good arguments to putting this in. The usual argument is 
that then one could take advantage of the internal data acess or something, 
but that generally pre-supposes that the public access methods are somehow 
inefficient or insufficient. If that's really the case, then the public 
access is sub-standard and that should be fixed. Serialisation should not be 
a "privaledged client".

my 2c worth of design :-)

-- 
Patrick Dowler
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