cLive ;-) has asked for the wisdom of the Perl Monks concerning the following question:

More a "I wonder" rather than an "I need to know", but...

Any way to do this: 

my @array = ('one', 'two', '', 'four', 'five');

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using only one qw()? ie 
my @array = qw(one two NULL four five);

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where NULL represents the empty string?

Of course, I could do this: 

my @array = qw(one two), '', qw(four five);

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but that seems somehow... ugly?

And thanks to converter, I realise the difference between different releases :)

So, send me your 2 cents...

cLive ;-)

ps - well, it *is* the weekend...

Replies are listed 'Best First'.
Re: Embed empty value using qw()
by rchiav (Deacon) on Sep 02, 2001 at 09:59 UTC
    According to perlop qw() is "exactly" like doing a 
    split(' ', q/STRING/);

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    That doesn't leave much room for an empty value. But for another way, you could fill the array using a slice.. 
    @array[0..4,6..9] = qw(0 1 2 3 4 6 7 8 9);

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    Still not pretty, but it's something..

    Rich

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      Actually, it's more like doing that in a BEGIN block--qw(a b c) becomes ('a', 'b', 'c') at compile time (at least in newer Perls).

      =cut
      --Brent Dax
      There is no sig.

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Re: Embed empty value using qw()
by trantor (Chaplain) on Sep 02, 2001 at 15:25 UTC

    What about something like:

    my @array = map { $_ eq 'NULL' ? '' : $_ } qw(one two NULL four five);

    It could be worth it when you have lots of NULLs

    -- TMTOWTDI

    Update: I didn't notice that cLive ;-) wanted an empty string and not an undef

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Re: Embed empty value using qw()
by andye (Curate) on Sep 03, 2001 at 14:13 UTC
    You could do this...
    
my $ns = '';
my @a = qw(one two 3 $ns five);
s/(\$.*)/$1/ee foreach @a;

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    andy. Update:

    Come to think of it, this seems neat & simple... 

    my @a = grep {s/^''$//;1} qw(one two 3 '' four five);

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    Do I get the prize? What was the prize, anyway? Hope it's ice-cream...
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Re: Embed empty value using qw()
by MrNobo1024 (Hermit) on Sep 03, 2001 at 19:27 UTC
    You could use 
    map { $_ ne 'NULL' && $_ } qw(one two NULL four five)

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    since && returns an empty string if the first condition is false.
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Re: Embed empty value using qw()
by dga (Hermit) on Sep 03, 2001 at 21:34 UTC

    Well it doesn't use qw and one would need a comment but. 

    my $stuff='one, two, , three, four'; #empty element between two and th
+ree
my @arr=split(/, /, $stuff); #split on space comma

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    Since its in single quotes it will quote sort of like qw. Optionally one could split on \s (no plus) which would mean any series of 2 spaces would be an empty value from split. And you could combine the two statements. 

    my @arr=split(/\s/, 'one two  three four'); #same effect as above

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    Of course the empty word is really subtle in the second example.

    Update: Fixed the first RE typo as suggested.

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      Er, shouldn't the regular expression for the split in the first example be /, /?

      =cut
      --Brent Dax
      There is no sig.

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