Perl DBI常数-如何访问？

Question

The documentation for getting type info includes this piece of suggested code for getting the mapping between code and integer:

foreach (@{ $DBI::EXPORT_TAGS{sql_types} }) {
    printf "%s=%d\n", $_, &{"DBI::$_"};
}

But perl 5.16.2 won't allow it:

Can't use string ("DBI::SQL_GUID") as a subroutine ref while "strict refs" in use

I don't know how to turn off strict refs and I suspect it wasn't the author's intention that anyone do so. How can this subroutine call be accomplished?

Answer 1

You can turn off strict 'refs' by doing this

{
    no strict 'refs';
    foreach (@{ $DBI::EXPORT_TAGS{sql_types} }) {
        printf "%s=%d\n", $_, &{"DBI::$_"};
    }   
}

Answer 2

Why would you put no strict 'refs'; on the outside? The following is more appropriate use of no strict 'refs'; :

for (@{ $DBI::EXPORT_TAGS{sql_types} }) {
    no strict 'refs';
    printf "%s=%d\n", $_, &{"DBI::$_"};
}

(And don't say anything about jmcneirney's being a microsecond faster because that would be wrong.)

Or, since \\& isn't subject to a strict refs check,

for (@{ $DBI::EXPORT_TAGS{sql_types} }) {
    my $ref = \&{"DBI::$_"};
    printf "%s=%d\n", $_, $ref->();
}