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Re^3: What one-liners do people actually use?

by Tanktalus (Canon)
on Dec 09, 2005 at 00:54 UTC ( #515433=note: print w/replies, xml ) Need Help??


in reply to Re^2: What one-liners do people actually use?
in thread What one-liners do people actually use?

Practically, speaking, yes. Literally, however, no. It's more like:

length_of() { echo $1 | wc -c } length_of some-string
The only time this is important is if some-string has spaces, wildcards, etc. You put single quotes around the string, which would prevent any of this from happening, while the OP didn't use quotes, thus shell metacharacters would be expanded.

That said, I'm betting that the OP wasn't counting on any of this, and that your shell code gets closer to what the OP really wanted anyway.

Also, the OP's code does work on Windows while yours, well, doesn't, unless you install the Cygwin tools or something. ;-) Not sure if that's important to parv or not.

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[hippo]: Understood. I'll have to go through the code and see if it's doing anything fancy with ties, dual-vars or non-scalars. In the end, it's probably a bug though.
[Corion]: Aaah - you should be able to do this with overload, but I would hit somebody really hard if they constructed objects that are true but the empty string, and you not knowing about the domain knowledge where this makes sense
[Eily]: you could tie a variable into not having the same value each time, if you like to make people who try to debug your code facepalm
[Corion]: perl -wle 'package o; use overload q("") => sub {warn "str"; ""}, bool => sub{warn "bool"; 1}; package main; my $o={}; bless $o => o; print "Yay" if ($o && !length($o))'
[Corion]: But people writing such code should document the objects they construct and why it makes sense for an object to be invisible as string while being true in a boolean context
[hippo]: That's equal parts clever and horrendous.
[Eily]: the overload version wouldn't return true with "$x" && !length $x though, I guess
[hippo]: The more I look at this code, the more $x is a plain old scalar and the more this condition will never be true. I'm calling it a bug at this point.

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