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Postings from July 2011
On Wed, Jul 20, 2011 at 12:03:54PM +0000, Ed Avis wrote: > Greg Lindahl <greg <at> blekko.com> writes: > > >We train a large fraction of our new employees to use perl. We don't > >use any of the perl beginner documentation for the initial training > >because it teaches them things that we don't have and don't want in > >our code. In this particular example, I think the ideal would be to > >start with lots of 3-arg opens and variables as filehandles, and then > >mention that 2-arg open and FH exists. > > +1 to that. If you teach the two-arg open, you must include a long list of > caveats listing all the cases where it does something magic. Once you have done > so there is no longer any simplicity advantage to the two-arg form. > > Beginner material must teach idioms which work reliably 100% of the time, not > interesting hacks which appear to accomplish the task but contain subtle magic > which will do something weird when the filename is '-' or starts with a > > character, although on the other hand you can prefix it with ./ to prevent that, > provided you also make sure it doesn't end in '|', etc etc... > > Indeed there is a case for two separate tutorials: > > A. How to open a file. > > B. How to use Perl's magic 'open' to do interesting things with > redirections and shell pipelines, provided you understand that it's not > in general safe to use string interpolation with a user-provided > filename. > > We do not help beginners by giving them (B) purporting to be (A). Indeed. And we help (beginners or otherwise) even less by pretending B doesn't exists, or (worse) that it's something evil. Don't forget we all dealt well with 2-arg open for a decade and a half without our servers being hijacked by every script that opened a file. AbigailThread Previous | Thread Next