Strange behaviour with a record in a guard

Ulf Wiger <>
Mon Mar 3 10:36:12 CET 2003


On Mon, 3 Mar 2003, Bengt Kleberg wrote:

>R#r1.f1 only gets the ''right'' element from the tuple.
>
>if you want to check the record type, as well as the value
>of a field, you need to write (here ''= R'' may be omitted
>if you are not interested in the whole record):
>
>foo( #r{f1=F1} = R ) when F1 == undefined ->
>	ok.

...or even

foo(#r{f1 = undefined}) ->
    ok.

(You don't have to bind R in this case, but the compiler
should of course figure that out.)

-- 
Ulf Wiger, Senior Specialist,
   / / /   Architecture & Design of Carrier-Class Software
  / / /    Strategic Product & System Management
 / / /     Ericsson AB, Connectivity and Control Nodes




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