Originally posted by: SystemAdmin

The EITHER function does not seem to work as advertised.

=EITHER(LOOKUP( DateA , Kind = "RTWM"), NONE) returns DateA
=EITHER(LOOKUP( DateA , Kind = "RTWM"), DateB) returns DateB
=EITHER(DateA, DateB) returns DateB

I only want to use DateB if DateA does not exists.

Note: DateB is located first in the data.

DSTX 6.7
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Originally posted by: SystemAdmin

Without seeing the data and the input tree, I would suggest IF(PRESENT(DateA,DateA)DateB) or similar syntax. The means if DateA is present, use it, else use DateB. If Either finds something, it won't continue looking.
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Originally posted by: SystemAdmin

You can't use 2 LOOKUPs in the same rule. It is what ascential call a (i think) consumable function where once it has read the data for the first lookup it does not reset to start a second lookup from the beginning of the data. There are a number of other functins that behave the same way.
If you do each lookup in a separate card and then check for the presence of the card in your final card it will work ok
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Originally posted by: SystemAdmin

Thank-you Jan, you stated my thoughts exactly.
Since the rule for which I would like to use the EITHER function is down about 2 levels of functional maps, I'll have to use a RUN map to implement your suggestion. While I don't like to use run maps, I think that in this situation I will be forced to.
It's unfortunate that the EITHER function does not work as it is defined in the documentation.
EITHER (try_this { , if_none—try_this } )

Returns

This function returns a single-object.
Returns try_this, if try_this does not evaluate to NONE. Returns if_none_try_this, if try_this evaluates to NONE. Returns the next if_none_try_this, if the first if_none_try_this evaluates to NONE, and so on.

Copyright © 2002 by Mercator Software, Inc.

It should read
Returns whatever argument is first in the data regardless of the order of arguments defined in the function.
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Originally posted by: SystemAdmin

It's not the EITHER that doesn't work, it's the LOOKUP (and searchup, searchdown).
The problem has been raised by lots of people for lots of versions but Mercator/Ascential and probably IBM say its a feature not a bug.

I think FIND works ok multiple times in a rule. Perhaps you could use this for the initial selection.
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Originally posted by: SystemAdmin

Sometimes, I just pass two copies of the input. It makes for flatter code that is easier to maintain.
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Originally posted by: SystemAdmin

Hey All,

I routinely use Jim's suggestion here. Hi Jim, it's me :-)

This behaviour has is what Mercator used to term "Binding" and it has always been billed as a feature, not a bug. The Extract function also will cause this. Actually, if you know how to use it, it can be sort of cool to use, but normally, it just rears it's ugly head and bites the unsuspecting user in the nether regions.

Brian Nobbe
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