phpMan > man > B::Xref

NAME
    B::Xref - Generates cross reference reports for Perl programs

SYNOPSIS
    perl -MO=Xref[,OPTIONS] foo.pl

DESCRIPTION
    The B::Xref module is used to generate a cross reference listing of all definitions and uses of
    variables, subroutines and formats in a Perl program. It is implemented as a backend for the
    Perl compiler.

    The report generated is in the following format:

        File filename1
          Subroutine subname1
            Package package1
              object1        line numbers
              object2        line numbers
              ...
            Package package2
            ...

    Each File section reports on a single file. Each Subroutine section reports on a single
    subroutine apart from the special cases "(definitions)" and "(main)". These report,
    respectively, on subroutine definitions found by the initial symbol table walk and on the main
    part of the program or module external to all subroutines.

    The report is then grouped by the Package of each variable, subroutine or format with the
    special case "(lexicals)" meaning lexical variables. Each object name (implicitly qualified by
    its containing Package) includes its type character(s) at the beginning where possible. Lexical
    variables are easier to track and even included dereferencing information where possible.

    The "line numbers" are a comma separated list of line numbers (some preceded by code letters)
    where that object is used in some way. Simple uses aren't preceded by a code letter.
    Introductions (such as where a lexical is first defined with "my") are indicated with the letter
    "i". Subroutine and method calls are indicated by the character "&". Subroutine definitions are
    indicated by "s" and format definitions by "f".

    For instance, here's part of the report from the *pod2man* program that comes with Perl:

      Subroutine clear_noremap
        Package (lexical)
          $ready_to_print   i1069, 1079
        Package main
          $&                1086
          $.                1086
          $0                1086
          $1                1087
          $2                1085, 1085
          $3                1085, 1085
          $ARGV             1086
          %HTML_Escapes     1085, 1085

    This shows the variables used in the subroutine "clear_noremap". The variable $ready_to_print is
    a my() (lexical) variable, introduced (first declared with my()) on line 1069, and used on line
    1079. The variable $& from the main package is used on 1086, and so on.

    A line number may be prefixed by a single letter:

    i   Lexical variable introduced (declared with my()) for the first time.

    &   Subroutine or method call.

    s   Subroutine defined.

    r   Format defined.

    The most useful option the cross referencer has is to save the report to a separate file. For
    instance, to save the report on *myperlprogram* to the file *report*:

      $ perl -MO=Xref,-oreport myperlprogram

OPTIONS
    Option words are separated by commas (not whitespace) and follow the usual conventions of
    compiler backend options.

    "-oFILENAME"
            Directs output to "FILENAME" instead of standard output.

    "-r"    Raw output. Instead of producing a human-readable report, outputs a line in
            machine-readable form for each definition/use of a variable/sub/format.

    "-d"    Don't output the "(definitions)" sections.

    "-D[tO]"
            (Internal) debug options, probably only useful if "-r" included. The "t" option prints
            the object on the top of the stack as it's being tracked. The "O" option prints each
            operator as it's being processed in the execution order of the program.

BUGS
    Non-lexical variables are quite difficult to track through a program. Sometimes the type of a
    non-lexical variable's use is impossible to determine. Introductions of non-lexical non-scalars
    don't seem to be reported properly.

AUTHOR
    Malcolm Beattie, mbeattie AT sable.uk.