Re: (Ovid) Re: No other way?

That's a good one... ;-). Thankx! ps. I had a slight mistake in my initial code. It would 'fail' if path started with a '/'. Therefore, this should be right:

sub get_parents {
  my (@p, $o); 
  for (grep !/^$/, split ("/",$_[0])) {push(@p,"$o/$_");$o.="/$_"}
  return \@p;
}
[download]

print join(" ", map { sprintf "%#02x", $_ }unpack("C*",pack("L",0x1234
+5678)))
[download]

Comment on Re: (Ovid) Re: No other way? Select or Download Code

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Re: Re: Re: No other way? by chip (Curate) on Dec 13, 2001 at 03:57 UTC
I suggest avoiding `/^$/` because regexes are a lot more expensive than calling `length`. Thus: `for (grep { length } split(m{/+}, $_[0])) # ...` -- Chip Salzenberg, Free-Floating Agent of Chaos	[reply] [d/l] [select]
Re5: No other way? by blakem (Monsignor) on Dec 13, 2001 at 08:01 UTC
Another reason to avoid /^$/ is that it non-intuitively matches a single newline: `#!/usr/bin/perl -wT use strict; # only one one of these is an "empty" string right? my @arr = ("", "\n", "dog", "cat"); my @haslength = grep {length} @arr; my @notempty = grep {!/^$/} @arr; print scalar @haslength, " members have length\n"; print scalar @notempty, " members are not \"empty\"\n"; __END__ =head1 OUTPUT 3 members have length 2 members are not "empty"` [download] So, /^$/ actually classifies a single newline as an "empty" string.... Sometimes thats what you want, but it isn't usually what people expect. -Blake	[reply] [d/l]
Re: Re: Re: Re: No other way? by greenFox (Vicar) on Dec 13, 2001 at 22:52 UTC
given that the grep for /^$/ was to skip the null first field returned by split (because the first character in the string was the delimiter "/"), wouldn't it be "better" (more readable) to just explicitly remove it- ie `s#^/##; # remove the leading delimiter` [download] The code as written silently munches all null fields which is fine because we don't expect a directory called null (ie in /foo/bar//rab/oof) but if the idiom is transported to another set of data... split /' '/ nicely removes any leading white space... it could be handy to have an option to do this for other delimiters. -- my $chainsaw = 'Perl';	[reply] [d/l]
Re: Re: Re: Re: Re: No other way? by chip (Curate) on Dec 14, 2001 at 01:40 UTC
Well, in order to do a substitution you might have to assign to a new variable so as not to modify the original value, and that could be a worse readability hit than the `grep`; depends on the context. PS: I think you meant `s#^/+##`, what with the possibility of multiple leading slashes. -- Chip Salzenberg, Free-Floating Agent of Chaos	[reply] [d/l] [select]