RE: [Quickfix-developers] Component blocks

[Shepheard, T. (London) <Tob...@ml...>]

I make it look a bit worse than it is - fieldMap.getField can of course
take a TransactTime object rather than the base type, which protects it
against data dictionary changes and the need to know the base type.=20
=20
Still, the question around using component blocks in an OO manner
remains :)

	-----Original Message-----
	From: qui...@li...
[mailto:qui...@li...] On Behalf Of
Shepheard, Toby (London)
	Sent: 18 January 2006 14:52
	To: qui...@li...
	Subject: [Quickfix-developers] Component blocks
=09
=09

	Hi all,=20

	I'm using QuickFIX/J, though I think this may be applicable to
the other implementations I'm not sure.=20

	What I'd like to do is write some helper methods to carry out
certain common actions based on component blocks. A typical example
would be the Instrument block, which appears in a number of guises:

	QuoteRequest message - here it is part of a repeating group,
NoRelatedSym.=20
	NewOrderSingle message - here it is part of the main
NewOrderSingle message=20

	I'd love to be able to pass in an "Instrument" object to a
method and do my thing with it, but there doesn't seem to be any such
object. Indeed, the only way I could find to extract Instrument data
from a common base class was to treat is as a FieldMap object, which
covers both Group and Message types. This seems to mean using a format
such as

	fieldMap.getField(new UtcTimeStampField(TransactTime.FIELD)=20

	Which is not very type-safe, as I'm just assuming the fieldMap
will have the Instrument block's fields, and is liable to break if
anything changes in the underlying data-dictionary. Is there a better
way to do this that is type-safe and reusable, regardless of the
underlying fieldMap type that the instrument block is a part of? I
realise component blocks have no "real" meaning, but they do provide a
common, logical construct that it seems  shame I can't leverage in a
nice OO way, especially considering the data dictionary contains all the
required data for generating such objects. If I am missing something,
please let me know :)

	Regards,=20
	Toby
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