Date: Tue, 20 May 2008 15:44:00 +0100 From: RW <fbsd06@mlists.homeunix.com> To: freebsd-questions@freebsd.org Subject: Re: Now what would you expect this to print out? Message-ID: <20080520154400.115e8817@gumby.homeunix.com.> In-Reply-To: <200805201133.50963.jonathan@hst.org.za> References: <7d6fde3d0805190149y7a3bfa75j2ca6a67cef66e8f6@mail.gmail.com> <20080519094603.GC12033@osiris.chen.org.nz> <20080520014133.3447c282@gumby.homeunix.com.> <200805201133.50963.jonathan@hst.org.za>
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On Tue, 20 May 2008 11:33:50 +0200 Jonathan McKeown <jonathan@hst.org.za> wrote: > On Tuesday 20 May 2008 02:41, RW wrote: > > On Mon, 19 May 2008 21:46:03 +1200 > > > > Jonathan Chen <jonc@chen.org.nz> wrote: > > > find /usr/src \( -name Makefile -or -name '*.mk' \) -print > > > > Why does that make a difference, when print always evaluates to > > true? > > > > x AND true = x > > > > so > > > > (a OR b) AND true = a OR b > > a OR (b AND true) = a OR b > > It makes a difference (as in programming) because -print is used for > its side-effect rather than its value, and the binding order > influences when the side-effect happens. That's still a bit counter-intuitive because in normal programming languages the binding order modifies side-effects via the evaluation order. And in both cases the evaluation order would be expected to be left-to-right, with -print running last. I guess what you are saying is that the side-effect of print is based-on a Boolean "running-value". And without the brackets, the first test has been evaluated, but not yet ORed into that "running-value", by the time that print runs.
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