`Usage: Text::CSV_Xs::getline(self, io)` 是什么意思？

Question

我不是一个程序员，而且对 Perl 很陌生。我目前正在编写一个小脚本来读取 CSV，对不同的字段进行一些评估，然后在满足某些条件时打印到另一个文件。我以为我已经完成了，但后来我收到了这条新消息：

“用法：Text::CSV_Xs::getline(self, io) at date_compare.pl 第 51 行第 3 行。”

我一直在努力寻找能够告诉我这条消息意味着什么的东西，但我迷路了。我知道这很简单。我的代码如下。请原谅我的无知。

#! /usr/local/ActivePerl-5.12/bin/perl

#this script will check to files, throw them into arrays and compare them
#to find entries in one array which meet specified criteria
#$field_file is the name of the file that contains the ablation date first,
#then the list of compared dates, then the low and high end date criteria, each
#value should end with a \n.
#$unfiltered_file is the name of the raw CSV with all the data
#$output_file is the name of the file the program will write to
use strict;
use 5.012;
use Text::CSV_XS;
use IO::HANDLE qw/getline/;
use Date::Calc qw/Decode_Date_US2 Delta_Days/;

my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ }) or
    die "Cannot use CSV: ".Text::CSV->error_diag ();

my ($field_file,
    $unfiltered_file,
    $output_file,
    @field_list,
    $hash_keys,
    %compare,
    $check,
    $i);
#Decode_Date_US2 scans a string and tries to parse any date within.
#($year,$month,$day)=Decode_Date_US2($string[,$language])
#Delta_Days returns the difference in days between the two given dates.
#$Dd = Delta_Days($year1,$month1,$day1, $year2,$month2,$day2);
sub days{
    Delta_Days(Decode_Days_US2(@compare{$field_list[0]}),
           Decode_Days_US2(@compare{$field_list[$i]}));
}

sub printout{
    $csv->print(<OUTPUTF>, $check) or die "$output_file:".$csv->error_diag();
}

print "\nEnter the check list file name: ";
chomp ($field_file = <STDIN>);
open FIELDF, "<", $field_file or die "$field_file: $!";
chomp (@field_list=<$field_file>);
close FIELDF or die "$field_file: $!";
print "\nEnter the raw CSV file name: ";
chomp ($unfiltered_file = <STDIN>);
print "\nEnter the output file name : ";
chomp ($output_file = <STDIN>);
open OUTPUTF, ">>", $output_file or die "$output_file: $!";
open RAWF, "<", $unfiltered_file or die "$unfiltered_file: $!";
if ($hash_keys = $csv->getline(<RAWF>)){
    $check = $hash_keys;
    &printout();
}else{die "\$hash_keys: ".$csv->error_diag();}

while ($check = $csv->getline (<RAWF>)){
    @compare{@$hash_keys}=@$check;    
    TEST: for ($i=1, $i==(@field_list-3), $i++){
        if (&days()>=$field_list[-2] && &days()<=$field_list[-1]){
            last TEST if (&printout());
    }
}    

Answer 1

Usage: Text::CSV_Xs::getline(self, io) at date_compare.pl line 51, line 3.

getline 显然需要一个文件句柄/IO::Handle，而您传递给它的是一个标量（包含从文件句柄中读取的一行）。

这意味着在您的线路上：

if ($hash_keys = $csv->getline(<RAWF>)){

你应该使用：

if ($hash_keys = $csv->getline( \*RAWF )){

改为。

（但你真的应该使用词法文件句柄，如下所示：）

open FIELDF, "<", $field_file or die "$field_file: $!";
chomp (@field_list=<$field_file>);       # Not sure how you expect this to work
close FIELDF or die "$field_file: $!";

会变成：

open my $fieldf, "<", $field_file or die "$field_file: $!";
chomp (@field_list=<$fieldf>);
close $fieldf or die "$field_file: $!";