B::Xref

El módulo B::Xref permite construir un listado de referencias cruzadas: Por ejemplo, dado el programa:

$ cat -n variables.pl
 1  #!/usr/bin/perl
 2  #Crear una cadena de caracteres
 3  $variable="Soy una variable que contiene una cadena";
 4  print("El contenido de \$variable es: \t $variable\n");
 5  #Crear una un numero real
 6  $variable=3.141616;
 7  print("El contenido de \$variable es: \t $variable\n");
 8  #Crear una un numero entero
 9  $variable=55;
10  print("El contenido de \$variable es: \t $variable\n");

Podemos obtener un listado haciendo:

$ perl -MO=Xref variables.pl
File variables.pl
  Subroutine (definitions)
    Package UNIVERSAL
      &VERSION          s0
      &can              s0
      &isa              s0
    Package attributes
      &bootstrap        s0
  Subroutine (main)
    Package main
      $variable         3, 4, 6, 7, 9, 10
variables.pl syntax OK

Si queremos redirigir la salida a fichero, podemos usar la opción -o

$ perl -MO=Xref,-omatrixP.idx matrixP.pl
$ cat -n matrixP.idx
     1  File matrixP.pl
     2    Subroutine (definitions)
     3      Package Internals
     4        &HvREHASH         s0
     5        &SvREADONLY       s0
     6        &SvREFCNT         s0
     7        &hash_seed        s0
     8        &hv_clear_placeholders  s0
     9        &rehash_seed      s0
    10      Package PerlIO
    11        &get_layers       s0
    12      Package Regexp
    13        &DESTROY          s0
    14      Package UNIVERSAL
    15        &VERSION          s0
    16        &can              s0
    17        &isa              s0
    18      Package main
    19        &matrixProd       s30
    20        &printMat         s47
    21    Subroutine (main)
    22      Package main
    23        $matA             53, 55, 58
    24        $matB             54, 55, 60
    25        $matC             55, 62
    26        &matrixProd       &55
    27        &printMat         &58, &60, &62
    28    Subroutine matrixProd
    29      Package (lexical)
    30        $i                i5, 20
    31        $j                i6, 17, 20, 22, 22, 25, 25
    32        $k                i6, 19, 22, 22
    33        $matA             i4, 7
    34        $matB             i4, 9
    35        $nColsA           i8, 13, 23
    36        $nColsB           i10, 25
    37        $nRowsA           i7, 27
    38        $nRowsB           i9, 13
    39        $refMatC          i11, 20
    40        @$i               20, 22
    41        @$k               22, 23, 23
    42        @$matA            7, 8
    43        @$matB            9, 10
    44        @$refMatC         20, 22
    45        @@$i              22, 22
    46        @@$matA           8, 22
    47        @@$matB           10, 22
    48        @@$refMatC        22, 29
    49        @@@$i             22, 27, 27
    50        @@@$matA          22
    51        @@@$matB          22
    52      Package ?
    53        @??               8, 10
    54      Package main
    55        @_                4
    56    Subroutine printMat
    57      Package (lexical)
    58        $i                i36, 41
    59        $mat              i33, 34
    60        $nCols            i35, 42
    61        $nRows            i34, 45
    62        @$i               41, 45, 45
    63        @$mat             34, 35
    64        @@$mat            35, 41
    65        @@@$mat           41
    66      Package ?
    67        @??               35
    68      Package main
    69        $j                39, 41, 42, 42
    70        @_                33