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Shell::Perl::Dumper(3pm) User Contributed Perl Documentation Shell::Perl::Dumper(3pm)

NAME

Shell::Perl::Dumper - Dumpers for Shell::Perl

SYNOPSYS

    use Shell::Perl::Dumper;
    $dumper = Shell::Perl::Dumper::Plain->new;
    print $dumper->dump_scalar($scalar);
    print $dumper->dump_list(@list);

DESCRIPTION

In "pirl", the result of the evaluation is transformed into a string to be printed. As this result may be a pretty complex data structure, the shell provides a hook for you to pretty-print these answers just the way you want.

By default, "pirl" will try to convert the results via "Data::Dump". That means the output will be Perl code that may be run to get the data structure again. Alternatively, the shell may use "Data::Dumper" or "Data::Dump::Streamer" with almost the same result with respect to the representation as Perl code. (But the output of the modules differ enough for sufficiently complex data.)

Other options are to set the output to produce YAML or a plain simple-minded solution which basically turns the result to string via simple interpolation.

All of these are implemented via dumper objects. Dumpers are meant to be used like that:

   $dumper = Some::Dumper::Class->new; # build a dumper
   $s = $dumper->dump_scalar($scalar); # from scalar to string
   $s = $dumper->dump_list(@list); # from list to string

METHODS

The following methods compose the expected API of a dumper, as used by Shell::Perl.

    $dumper = $class->new(@args);

Constructs a dumper.

    $s = $dumper->dump_scalar($scalar);

Turns a scalar into a string representation.

    $s = $dumper->dump_list(@list);

Turns a list into a string representation.

    $ok = $class->is_available

This is an optional class method. If it exists, it means that the class has external dependencies (like "Shell::Perl::Data::Dump" depends on "Data::Dump") and whether these may be loaded when needed. If they can, this method returns true. Otherwise, returning false means that a dumper instance of this class probably cannot work. This is typically because the dependency is not installed or cannot be loaded due to an installation problem.

This is the algorithm used by Shell::Perl XXX XXX XXX

    1.

THE STANDARD DUMPERS

Shell::Perl provides four standard dumpers:

    * Shell::Perl::Data::Dump
    * Shell::Perl::Data::Dumper
    * Shell::Perl::Data::Dump::Streamer
    * Shell::Perl::Dumper::YAML
    * Shell::Perl::Dumper::Plain

which corresponds to the four options of the command " :set out ": "D", "DD", "DDS", "Y", and "P" respectively.

Data::Dump

The package "Shell::Perl::Data::Dump" implements a dumper which uses Data::Dump to turn Perl variables into a string representation.

It is used like this:

    use Shell::Perl::Dumper;
    if (!Shell::Perl::Data::Dump->is_available) {
        die "the dumper cannot be loaded correctly"
    }
    $dumper = Shell::Perl::Data::Dump->new;
    print $dumper->dump_scalar($scalar);
    print $dumper->dump_list(@list);

Examples of its output:

    pirl > :set out D
    pirl > { a => 3 } #scalar
    { a => 3 }
    pirl > (1, 2, "a") #list
    (1, 2, "a")

Data::Dumper

The package "Shell::Perl::Data::Dumper" implements a dumper which uses Data::Dumper to turn Perl variables into a string representation.

It is used like this:

    use Shell::Perl::Dumper;
    if (!Shell::Perl::Data::Dumper->is_available) {
        die "the dumper cannot be loaded correctly"
    }
    $dumper = Shell::Perl::Data::Dumper->new;
    print $dumper->dump_scalar($scalar);
    print $dumper->dump_list(@list);

Examples of its output:

    pirl > :set out DD
    pirl > { a => 3 } #scalar
    @var = (
             {
               'a' => 3
             }
           );
    pirl > (1, 2, "a") #list
    @var = (
             1,
             2,
             'a'
           );

YAML

The package "Shell::Perl::Dumper::YAML" implements a dumper which uses YAML::Syck or YAML to turn Perl variables into a string representation.

It is used like this:

    use Shell::Perl::Dumper;
    if (!Shell::Perl::Dumper::YAML->is_available) {
        die "the dumper cannot be loaded correctly"
    }
    $dumper = Shell::Perl::Dumper::YAML->new;
    print $dumper->dump_scalar($scalar);
    print $dumper->dump_list(@list);

Examples of its output:

    pirl > :set out Y
    pirl @> { a => 3 } #scalar
    ---
    a: 3
    pirl @> (1, 2, "a") #list
    --- 1
    --- 2
    --- a

When loading, "YAML::Syck" is preferred to "YAML". If it is not available, the "YAML" module is the second option.

Data::Dump::Streamer

The documentation is yet to be written.

Plain Dumper

The package "Shell::Perl::Dumper::Plain" implements a dumper which uses string interpolation to turn Perl variables into strings.

It is used like this:

    use Shell::Perl::Dumper;
    $dumper = Shell::Perl::Dumper::Plain->new;
    print $dumper->dump_scalar($scalar);
    print $dumper->dump_list(@list);

Examples of its output:

    pirl > :set out P
    pirl > { a => 3 } #scalar
    HASH(0x1094d2c0)
    pirl > (1, 2, "a") #list
    1       2       a

SEE ALSO

See Shell::Perl for more documentation.

COPYRIGHT AND LICENSE

Copyright (C) 2007–2017 by Adriano R. Ferreira

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

2022-06-17 perl v5.34.0