FAQ 5.12 How can I write() into a string?

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5.12: How can I write() into a string?

    (contributed by brian d foy)

    If you want to "write" into a string, you just have to <open> a
    filehandle to a string, which Perl has been able to do since Perl 5.6:

            open FH, '>', \my $string;
            write( FH );

    Since you want to be a good programmer, you probably want to use a
    lexical filehandle, even though formats are designed to work with
    bareword filehandles since the default format names take the filehandle
    name. However, you can control this with some Perl special
    per-filehandle variables: $^, which names the top-of-page format, and $~
    which shows the line format. You have to change the default filehandle
    to set these variables:

            open my($fh), '>', \my $string;

            { # set per-filehandle variables
            my $old_fh = select( $fh );
            $~ = 'ANIMAL';
            $^ = 'ANIMAL_TOP';
            select( $old_fh );

            format ANIMAL_TOP =
             ID  Type    Name

            format ANIMAL =
            @##   @<<<    @<<<<<<<<<<<<<<
            $id,  $type,  $name

    Although write can work with lexical or package variables, whatever
    variables you use have to scope in the format. That most likely means
    you'll want to localize some package variables:

            local( $id, $type, $name ) = qw( 12 cat Buster );
            write( $fh );

            print $string;

    There are also some tricks that you can play with "formline" and the
    accumulator variable $^A, but you lose a lot of the value of formats
    since "formline" won't handle paging and so on. You end up
    reimplementing formats when you use them.


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