使用存储在哈希值中的文件句柄的语法错误

Question

我正在尝试使用单行代码，根据行本身字段的内容将从输入源读取的行写入不同的文件。

我的方法是使用散列来存储文件句柄以避免多次打开同一个文件，一旦在新的行读取。

但是使用存储文件句柄的散列值与普通 print/printf 调用，例如

print $hash{ $field_value } "String"

导致编译错误。例如，将 $hash{ $field_value } 替换为 STDERR 会导致干净的编译。

下面是一个单行示例。

$ cat /tmp/input_file 
mail1.sql:INSERT INTO
mail2.sql:INSERT INTO
mail3.sql:INSERT INTO
mail4.sql:INSERT INTO
mail6.sql:INSERT INTO
mail7.sql:INSERT INTO
mail8.sql:INSERT INTO
mail9.sql:INSERT INTO
maildev.sql:INSERT INTO

$ perl -C -nE '
m{^(?<server>mail[^.]+)\.sql:(?<string>INSERT INTO)};
exists $fd->{$+{server}} or open($fd->{$+{server}}, ">>", "/tmp/". $+{server}.".tmp.sql");
print sprintf(qq{server %s.domain.tld command %s;\n}, $+{server}, $+{string});
' /tmp/input_file 
server mail1.domain.tld command INSERT INTO;
server mail2.domain.tld command INSERT INTO;
server mail3.domain.tld command INSERT INTO;
server mail4.domain.tld command INSERT INTO;
server mail6.domain.tld command INSERT INTO;
server mail7.domain.tld command INSERT INTO;
server mail8.domain.tld command INSERT INTO;
server mail9.domain.tld command INSERT INTO;
server maildev.domain.tld command INSERT INTO;

# The files were opened, creating them. print-ing to STDOUT works fine.

$ ls -1  /tmp/mail*sql
/tmp/mail1.tmp.sql
/tmp/mail2.tmp.sql
/tmp/mail3.tmp.sql
/tmp/mail4.tmp.sql
/tmp/mail6.tmp.sql
/tmp/mail7.tmp.sql
/tmp/mail8.tmp.sql
/tmp/mail9.tmp.sql
/tmp/maildev.tmp.sql

# Now using $fd->{$+{server}} as filehandle for print

$ perl -C -nE '
m{^(?<server>mail[^.]+)\.sql:(?<string>INSERT INTO)};
exists $fd->{$+{server}} or open($fd->{$+{server}}, ">>", "/tmp/". $+{server}.".tmp.sql");
print $fd->{$+{server}} sprintf(qq{server %s.domain.tld command %s;\n}, $+{server}, $+{string});
' /tmp/input_file
syntax error at -e line 4, near "} sprintf"
syntax error at -e line 5, near ";}"
Execution of -e aborted due to compilation errors.

# Simplifying further

$ perl -C -nE '
my $a = "test";                                      
exists $fd->{$a} or open($fd->{$a}, ">>", "/tmp/". $a.".tmp.sql");
print $fd->{$a} sprintf(qq{AAA %s AAA\n}, $a);
' /tmp/input_file
syntax error at -e line 4, near "} sprintf"
BEGIN not safe after errors--compilation aborted at -e line 4.

我已经尝试使用 perl 5.22 和 5.30 进行此操作，只是为了检查它是否是最近修复的某种错误。

也许我遗漏了一些明显的东西，但我看不到什么。

有人知道吗？

提前致谢。

Answer 1

您需要将手柄包裹在一个裸块中。

print { $hash{ $field_value } } "String";

这在 print perldoc 中有记录。

If you're storing handles in an array or hash, or in general whenever you're using any expression more complex than a bareword handle or a plain, unsubscripted scalar variable to retrieve it, you will have to use a block returning the filehandle value instead, in which case the LIST may not be omitted:
print { $files[$i] } "stuff\n";
print { $OK ? *STDOUT : *STDERR } "stuff\n";

使用存储在哈希值中的文件句柄的语法错误

Syntax error using a filehandle stored in a hash value

perl

syntax-error

filehandle