In Perl, how can I write the output of Dumper to a file?

Question

How can I make Data::Dumper write a dump into a file?

Solution 1

Don't forget that you can specify the file handle to print to as in

print $LOG Dumper( \%some_complex_hash );

or use File::Slurp:

write_file 'mydump.log', Dumper( \%some_complex_hash );

Further thoughts: You might want to get into the habit of using:

warn Dumper( \%some_complex_hash );

and redirecting standard error to a file when you invoke your script (how you do this depends on the shell). For example:

 C:\Temp> sdf.pl 2>dump

Solution 2

Use print

print FILE Data::Dumper->Dump($object);

Solution 3

The question is a bit unclear, but are you looking for something like this?

open my $FH, '>', 'outfile';
print $FH Dumper(\%data);
close $FH;

You can restore the data later by using eval.

Comments

[Telemachus]

I'm curious: what advantage does File::Slurp offer here?

[Telemachus]

For storing and restoring later, Storable is a much better idea than Data::Dumper + eval: search.cpan.org/perldoc?Storable

[silbana]

If all I want is to dump a complex data structure to a file for debugging purposes, it is more self contained than open / print / close: no filehandles or error messages to mess with.

[daotoad]

Telemachus is correct. Storable, YAML, JSON, DBM::Deep or any of one million other serialization modules is a better choice than Data::Dumper + eval.

[patz]

@SinanÜnür how is $LOG supposed to be used. should $LOG point to a file open ($LOG, '>', 'file.txt');

[silbana]

@patz $LOG is a file handle, as I clearly state up front.