Re: [Gretl-devel] isnull() / exists() documentation for lists reloaded
On Fri, 18 Nov 2016, Allin Cottrell wrote:
Anyway... we could regularize this by dropping the current practice
of
manufacturing an empty list corresponding to no-argument, although this would
mean that "null" has a somewhat different meaning on the right-hand side of
an assignment (empty object) and as the default for a function argument
(non-existent). Urgh. It's hard to see a way out of this that's not rather
nastily backward-incompatible.
I must have used the idiom "list X = null" several hundreds of times in my
scripts. There's no way one could make this illegal without wreaking
havoc.
OTOH, "nelem(X) == 0" is a very nice and compact logical condition that
inbe could use in place of isnull() or similar functions.
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Riccardo (Jack) Lucchetti
Dipartimento di Scienze Economiche e Sociali (DiSES)
Università Politecnica delle Marche
(formerly known as Università di Ancona)
r.lucchetti(a)univpm.it
http://www2.econ.univpm.it/servizi/hpp/lucchetti
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