For the DBI case, the correct answer is definitely placeholders.

However, in the general case, consider Interpolation. It's pretty nifty. It lets you define "arbitrary interpolation semantics".

From its man page:

For example, you can say

    use Interpolation 
        money     => \&commify_with_dollar_sign,
        E         => 'eval',
        placename => 'ucwords';

And then you can write these:

    print "3 + 4 = $E{3+4}";
    # Prints  ``3 + 4 = 7''

    $SALARY = 57500;
    print "The salary is $money{$SALARY}";
    # Prints  ``The salary is $57,500.00''
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use vars qw/$dbh/;
use DBI;
$dbh = DBI->connect('baz', 'foo', 'bar', 'Oracle');

use Interpolation quoteit => sub { $dbh->quote(@_) };
print "select * from foo where bar = $quoteit{baz}";
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