Perl子例程可以返回数据但可以继续处理吗? [英] Can a Perl subroutine return data but keep processing?

问题描述

有什么办法让子例程在仍在处理的同时将数据发送回去?例如(此示例仅用于说明)-子例程读取文件.在读取文件时，如果满足某些条件，则返回"该行并继续进行处理.我知道有些人会回答-您为什么要这样做?以及为什么不只是...?，但我真的很想知道这是否可行.

Is there any way to have a subroutine send data back while still processing? For instance (this example used simply to illustrate) - a subroutine reads a file. While it is reading through the file, if some condition is met, then "return" that line and keep processing. I know there are those that will answer - why would you want to do that? and why don't you just ...?, but I really would like to know if this is possible.

推荐答案

实现此类功能的常用方法是使用回调函数:

A common way to implement this type of functionality is with a callback function:

{
    open my $log, '>', 'logfile' or die $!;
    sub log_line {print $log @_}
}

sub process_file {
    my ($filename, $callback) = @_;
    open my $file, '<', $filename or die $!;
    local $_;
    while (<$file>) {
        if (/some condition/) {
             $callback->($_)
        }
        # whatever other processing you need ....
    }
}

process_file 'myfile.txt', \&log_line;

，甚至没有命名回调:

process_file 'myfile.txt', sub {print STDERR @_};

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