C::DynaLib::Struct - Tool for handling the C `struct' data type
use C::DynaLib::Struct; Define C::DynaLib::Struct( $struct_tag, $template0, \@field_names0, [$template1, \@field_names1,] ... ); C::DynaLib::Struct::Parse <<ENDC; struct packet { unsigned short header; unsigned short flags; unsigned char payload[28]; }; ENDC $rstruct = tie( $struct, $struct_tag [, @initializer_list] ); $value = $rstruct->my_field(); $rstruct->my_field( $new_value ); $pointer_to_struct = pack( 'p', $struct ); $struct = $new_struct; # assigns all fields at once # after passing pointer-to-struct to a C function: $rstruct->Unpack(); $returned_value = $rstruct->my_field();
When mixing Perl and C, the conversion of data types can be rather tedious and error-prone. This module provides an abstraction from Perl's pack and unpack operators for using structures whose member data types and positions do not change.
pack
unpack
Here are some examples of C code that deals with a struct. On the right are some possible Perl equivalents.
struct
C Perl - ---- typedef struct { use C::DynaLib::Struct; int m_int; Define C::DynaLib::Struct( double m_double; 'Foo', char * m_string; 'i' => ['m_int'], } Foo; 'd' => ['m_double'], 'p' => ['m_string'] ); # or, equivalently, Define C::DynaLib::Struct('Foo', 'idp', [qw(m_int m_double m_string)]); Foo foo; Foo *pfoo = &foo; $rfoo = tie ($foo, 'Foo'); i = pfoo->m_int; $i = $rfoo->m_int; d = foo.m_double; $d = (tied $foo)->m_double; pfoo->m_string = "hi"; $rfoo->m_string("hi"); Foo bar; tie ($bar, 'Foo'); bar = foo; $bar = $foo; void do_foo(Foo *arg); use C::DynaLib; $lib = new C::DynaLib("-lfoo"); $do_foo = $lib->DeclareSub("do_foo","","P"); # or you could write an XSUB. do_foo(&foo); &$do_foo($foo); returned_i = foo.m_int; $rfoo->Unpack(); $returned_i = $rfoo->m_int;
Data member access is through autoloaded methods, so actual existing methods are not allowed as structure member names. Currently, the illegal names are AUTOLOAD, TIESCALAR, FETCH, STORE, and Unpack.
The names of Structs themselves must be allowable package names. Using an existing package name will cause problems.
structs mean different things to different C compilers on different machines. Use caution when assigning pack codes to C data types.
Convert::Binary::C, perlfunc(1) (for pack), perlref(1), perltie(1).
To install C::DynaLib, copy and paste the appropriate command in to your terminal.
cpanm
cpanm C::DynaLib
CPAN shell
perl -MCPAN -e shell install C::DynaLib
For more information on module installation, please visit the detailed CPAN module installation guide.