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Postings from July 2011
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).
--
Ed Avis <eda@waniasset.com>
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