具有Glob的Bizarrer Perl行为 [英] Bizarrer perl behavior with glob

问题描述

use strict;
use warnings;
#only linux
#use diagnostics;

# - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - - -
sub in_function {
    my $file = shift;

    glob($file) or die ("$file file was not found\n"); #this fails second time called

    # this is ok second time called
    #my @dummy = glob($file) or die ("$file file was not found\n");
}
# - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - -
my $file = "/tmp/file1*.pdf";
glob($file) or die ("$file file was not found\n");
in_function($file);
$file = "/tmp/file2*.pdf";
glob($file) or die ("$file file was not found\n");
in_function($file);

第一个球很好 第一个in_function glob很好 第二个球很好 第二个in_function glob失败 为什么在函数内调用时需要将glob分配给变量?

First glob is fine First in_function glob is fine Second glob is fine Second in_function glob fails Why do I need to assign glob to a variable when called within a function?

推荐答案

来自 perldoc -f glob

在标量上下文中，glob遍历此类文件名扩展，当列表用完时返回undef.

In scalar context, glob iterates through such filename expansions, returning undef when the list is exhausted.

以下将解决问题:

() = glob($file) 
   or die ...;

但是您可能想知道匹配项是什么，所以您可以使用

But you problably want to know what the matches are, so you can use

my @matches = glob($file) 
   or die ...;

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