How do I pass parameters to the File::Find subroutine that processes each file?

问题

Using File::Find, how can I pass parameters to the function that processes each file?

I have a Perl script that traverses directories in order to convert some 3-channel TIFF files to JPEG files (3 JPEG files per TIFF file). This works, but I would like to pass some parameters to the function that processes each file (short of using global variables).

Here is the relevant part of the script where I have tried to pass the parameter:

use File::Find;

sub findFiles
{
    my $IsDryRun2 = ${$_[0]}{anInIsDryRun2};
}

find ( { wanted => \&findFiles, anInIsDryRun2 => $isDryRun }, $startDir);

$isDryRun is a scalar. $startDir is a string, full path to a directory.

$IsDryRun2 is not set:

Use of uninitialized value $IsDryRun2 in concatenation (.) or string at TIFFconvert.pl line 197 (#1) (W uninitialized) An undefined value was used as if it were already defined. It was interpreted as a "" or a 0, but maybe it was a mistake. To suppress this warning assign a defined value to your variables.

(The old call without parameters was: find ( \&findFiles, $startDir); )

Test platform (but the production home will be a Linux machine, Ubuntu 9.1, Perl 5.10, 64 bit): ActiveState Perl 64 bit. Windows XP. From perl -v: v5.10.0 built for MSWin32-x64-multi-thread Binary build 1004 [287188] provided by ActiveState.

回答1:

You need to create a sub reference that calls your wanted sub with the desired parameters:

find( 
  sub { 
    findFiles({ anInIsDryRun2 => $isDryRun });
  },
  $startDir
);

This is, more-or-less, currying. It's just not pretty currying. :)

回答2:

You can create any sort of code reference you like. You don't have to use a reference to a named subroutine. For many examples of how to do this, see my File::Find::Closures module. I created that module to answer precisely this question.

回答3:

See the PerlMonks entry Why I hate File::Find and how I (hope I) fixed it describing how to do it with closures.

回答4:

#
# -----------------------------------------------------------------------------
# Read directory recursively and return only the files matching the regex
# for the file extension. Example: Get all the .pl or .pm files:
#     my $arrRefTxtFiles = $objFH->doReadDirGetFilesByExtension ($dir, 'pl|pm')
# -----------------------------------------------------------------------------
sub doReadDirGetFilesByExtension {
     my $self = shift;    # Remove this if you are not calling OO style
     my $dir  = shift;
     my $ext  = shift;

     my @arr_files = ();
     # File::find accepts ONLY single function call, without params, hence:
     find(wrapp_wanted_call(\&filter_file_with_ext, $ext, \@arr_files), $dir);
     return \@arr_files;
}

#
# -----------------------------------------------------------------------------
# Return only the file with the passed extensions
# -----------------------------------------------------------------------------
sub filter_file_with_ext {
    my $ext     = shift;
    my $arr_ref_files = shift;

    my $F = $File::Find::name;

    # Fill into the array behind the array reference any file matching
    # the ext regex.
    push @$arr_ref_files, $F if (-f $F and $F =~ /^.*\.$ext$/);
}

#
# -----------------------------------------------------------------------------
# The wrapper around the wanted function
# -----------------------------------------------------------------------------
sub wrapp_wanted_call {
    my ($function, $param1, $param2) = @_;

    sub {
      $function->($param1, $param2);
    }
}

来源：https://stackoverflow.com/questions/2056649/how-do-i-pass-parameters-to-the-filefind-subroutine-that-processes-each-file

标签

perl

file-find