http://www.perlmonks.org?node_id=510919


in reply to Passing a database connection

Hey! Shouldn't my $dbh; sub new { $dbh = @_; } actually be my $dbh; sub new { $dbh = @_[0]; } ? Try it! It might work! This is because when passing arguments, the @_ has to have an index, starting at 0. If you would have two arguments, one would be @_[0](this is equal to your first argument) and another would be @_1(this is equal to your second, which you luckily don't have).

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Re^2: Passing a database connection
by ikegami (Patriarch) on Nov 22, 2005 at 21:37 UTC
    Actually
    $dbh = $_[0];
    or
    ($dbh) = @_;
    or
    $dbh = shift(@_);
    or
    $dbh = shift;
    but yes.
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Re^2: Passing a database connection
by dragonchild (Archbishop) on Nov 23, 2005 at 02:23 UTC
    It shouldn't be @_[0] because that's the arrayslice consisting of the 0th element. If you turn warnings on, it will tell you about this. Arrayslicing is really cool. Try the following snippet: 
    my @x = 0 .. 9;
print "@x[2..4]\n";
print "@x[3,5,7]\n";
my @y = 4..6;
print "@x[@y]\n";
@x[7..9] = @y;
print "@x\n";

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    The reason why you don't want to use the arrayslice form when you want to extract a single element is, while it has been special-cased to work in the case of my $x = @x[2]; (it should assign 1 and not 2), it won't work in this case: 

    sub foo {
    wantarray ? 3 : 5;
}

my @x;
@x[2] = foo();
my $x = foo();
print "$x[2] <-> $x\n";

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    @x[2] is list context, not scalar context.
    My criteria for good software:
    1. Does it work?
    2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?
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      I see what you are saying. I made a mistake. It should've been $_[0], no?

      =d(o_o)b=

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