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Date:         Mon, 26 Apr 2004 14:10:02 -0400
Reply-To:     "Fehd, Ronald J. (PHPPO)" <rjf2@CDC.GOV>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
Comments:     cc: Quentin McMullen <quentin_mcmullen@BROWN.EDU>
From:         "Fehd, Ronald J. (PHPPO)" <rjf2@CDC.GOV>
Subject:      Re: symchk: checking for macro variable existance
Content-Type: multipart/mixed;

Quentin writes > I would agree that revising to upcase(name) sounds like good > defensive coding. Would just add that there is a cost to > upcasing strings unnecessarily (which I have at times been > willing to pay). I believe when you use the upcase() > function on the where statement, sas cannot use any available > index. So I've seen things slow down a *lot* when using a > where statement against a big dictionary table, and adding > upcase() in order to be defensive. So there is a cost to > weigh against the benefit. In many cases, it's may be worth > the cost for the defensive gain (wasn't too long ago that all > variable names were upcase, and I'd imagine some macros > started breaking when they went to mix case in v7).

point well taken: yes, I am aware of the cost of adding functions to a where clause. in this case, we're already behind the 8-ball because we're reading a view: SAShelp.vMacro.

in the long run, I can's see that this function will be used a great deal it is a pretty esoteric tool,

that said I am/will be using it in a lot of fan-in macros i.e. sub-routines called often by many other routines/macros. so perhaps I shall just put that upcase(name) in the change notes for the far-off future when the names are Upper- and Lowercased and it breaks.

> >The macro had > >%let DsId = %sysfunc(open(SAShelp.vMacro > >(where = (name = "%UPCASE(&Name)")))); > > > >and the question was > >-- with regard to defensive programming -- > >whether this was more robust: > >(where = (upcase(name) = "%UPCASE(&Name)")))); > > > >TechSupport replied: > > > >> I cannot guarantee the future, > >> but at this point in time, > >> yes they are stored in upper case. > >> I do not know of any plans to change that. > > > >I'm planning to make that change: > >no fear for that macro breaking > >and a I'll always have a good night's sleep when I remember it. > > > >Ron Fehd the robust macro maven CDC Atlanta GA USA RJF2@cdc.gov > > > >Efficiency is intelligent laziness. -David Dunham > >... and defensive coding for robustness


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