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Net::protoent(3perl) Perl Programmers Reference Guide Net::protoent(3perl)


Net::protoent - by-name interface to Perl's built-in getproto*() functions


 use Net::protoent;
 $p = getprotobyname(shift || 'tcp') || die "no proto";
 printf "proto for %s is %d, aliases are %s\n",
    $p->name, $p->proto, "@{$p->aliases}";
 use Net::protoent qw(:FIELDS);
 getprotobyname(shift || 'tcp') || die "no proto";
 print "proto for $p_name is $p_proto, aliases are @p_aliases\n";


This module's default exports override the core getprotoent(), getprotobyname(), and getnetbyport() functions, replacing them with versions that return "Net::protoent" objects. They take default second arguments of "tcp". This object has methods that return the similarly named structure field name from the C's protoent structure from netdb.h; namely name, aliases, and proto. The aliases method returns an array reference, the rest scalars.

You may also import all the structure fields directly into your namespace as regular variables using the :FIELDS import tag. (Note that this still overrides your core functions.) Access these fields as variables named with a preceding "p_". Thus, "$proto_obj->name()" corresponds to $p_name if you import the fields. Array references are available as regular array variables, so for example "@{ $proto_obj->aliases() }" would be simply @p_aliases.

The getproto() function is a simple front-end that forwards a numeric argument to getprotobyport(), and the rest to getprotobyname().

To access this functionality without the core overrides, pass the "use" an empty import list, and then access function functions with their full qualified names. On the other hand, the built-ins are still available via the "CORE::" pseudo-package.


While this class is currently implemented using the Class::Struct module to build a struct-like class, you shouldn't rely upon this.


Tom Christiansen

2021-04-29 perl v5.32.1