Re: Re: spaces in filenames

You say:
You should pass a pattern as its first argument, but instead you're passing a scalar.

Yes, split does expect a pattern. But no, it does not have to be delimited with forward slashes. In fact, Perl doesn't even require delimiters here. A scalar value in a variable will be interpreted as a pattern also. Either of the following cases works fine...

my $str = 'this_is_a_group_of_words';
my @ary = split "_", $str;
print "[$_]\n" for @ary;

my $str = 'this_is_a_group_of_words';
my $pat = '_';
my @ary = split $pat, $str;
print "[$_]\n" for @ary;
[download]

perldoc -f split says "The pattern "/PATTERN/" may be replaced with an expression to specify patterns that vary at run-time." but then confuses things by going on with, "(To do runtime compilation only once, use "/$variable/o".)" which makes it look like you still need the slashes. (Which you do if you want to add the '/o'.)

Camel 3, page 796, is more clear on this point when it says "if you supply a string instead of a regular expression, it will be interpreted as a regular expression anyway."

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problem space is also a mess." - Larry Wall

Comment on Re: Re: spaces in filenames Download Code

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Re: Re: Re: spaces in filenames by fokat (Deacon) on Feb 03, 2003 at 03:23 UTC
dvergin said: A scalar value in a variable will be interpreted as a pattern also. ~~I beg to differ. Take a look at the code below:~~ bash-2.05a$ perl -e 'print scalar(split("\W", "one two three")), "\n";' 1 bash-2.05a$ perl -e 'print scalar(split("\\W", "one two three")), "\n";' 3 bash-2.05a$ perl -e 'print scalar(split(/\W/, "one two three")), "\n";' 3 As you see, both versions produce a different result. My interpretation of your quote to The Camel (and to the fact that the original code compiles at all), is that `split()` is using the literal string as exactly that, a literal string that must occur verbatim. ~~This might have changed at some time, though.~~ I have vague recollections of using a literal with `split()`, but that was way back I guess. I am running 5.8.0 here, BTW. ++ for dvergin for researching his answer :) Update: As pointed out by MarkM, the literal string is indeed interpreted as a regular expression. It's just that `\` must be escaped in my example, so my conclusion turned out to be wrong. ++ to MarkM for showing me the light... Best regards -lem, but some call me fokat	[reply]
Re: Re: Re: Re: spaces in filenames by MarkM (Curate) on Feb 03, 2003 at 03:46 UTC
You are correct that "\W" produces a different result from /\W/ as a first argument to split(). You are not correct in concluding that this means split() is assuming that a quoted string is a literal. Examples: `$ perl -e '$t = "abc,def"; @t = split("\\W", $t); print "@t\n"' abc def` [download] `$ perl -e '$a = "abc,def"; @a = split("[^a-z]", $a); print "@a\n"' abc def` [download] In both cases, the string is being interpretted as a regular expression. As a string, a different set of interpolation rules apply.	[reply] [d/l] [select]


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