Страницы справочника OS X

Эта страница руководства для  версии 10.9 Mac OS X

Читать страницы руководства

B::Xref(3pm)                          Perl Programmers Reference Guide                          B::Xref(3pm)



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 nonlexical
       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@sable.ox.ac.uk.



perl v5.16.2                                     2012-10-25                                     B::Xref(3pm)