in reply to Re: spaces in filenames
in thread 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;

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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."

------------------------------------------------------------
"Perl is a mess and that's good because the
problem space is also a mess." - Larry Wall

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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]

      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

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      $ 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.

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