NAME

       Data::Dump::Trace - Helpers to trace function and method calls

SYNOPSIS

         use Data::Dump::Trace qw(autowrap mcall);

         autowrap("LWP::UserAgent" => "ua", "HTTP::Response" => "res");

         use LWP::UserAgent;
         $ua = mcall(LWP::UserAgent => "new");      # instead of LWP::UserAgent->new;
         $ua->get("http://www.example.com")->dump;

DESCRIPTION

       The following functions are provided:

       autowrap( $class )
       autowrap( $class => $prefix )
       autowrap( $class1 => $prefix1,  $class2 => $prefix2, ... )
       autowrap( $class1 => \%info1, $class2 => \%info2, ... )
           Register classes whose objects are are automatically wrapped when returned by one of
           the call functions below.  If $prefix is provided it will be used as to name the
           objects.

           Alternative is to pass an %info hash for each class.  The recognized keys are:

           prefix => $string
               The prefix string used to name objects of this type.

           proto => \%hash
               A hash of prototypes to use for the methods when an object is wrapped.

       wrap( name => $str, func => \&func, proto => $proto )
       wrap( name => $str, obj => $obj, proto => \%hash )
           Returns a wrapped function or object.  When a wrapped function is invoked then a trace
           is printed after the underlying function has returned.  When a method on a wrapped
           object is invoked then a trace is printed after the methods on the underlying objects
           has returned.

           See "Prototypes" for description of the "proto" argument.

       call( $name, \&func, $proto, @ARGS )
           Calls the given function with the given arguments.  The trace will use $name as the
           name of the function.

           See "Prototypes" for description of the $proto argument.

       mcall( $class, $method, $proto, @ARGS )
       mcall( $object, $method, $proto, @ARGS )
           Calls the given method with the given arguments.

           See "Prototypes" for description of the $proto argument.

       trace( $symbol, $prototype )
           Replaces the function given by $symbol with a wrapped function.

   Prototypes
       Note: The prototype string syntax described here is experimental and likely to change in
       revisions of this interface.

       The $proto argument to call() and mcall() can optionally provide a prototype for the
       function call.  This give the tracer hints about how to best format the argument lists and
       if there are in/out or out arguments.  The general form for the prototype string is:

          <arguments> = <return_value>

       The default prototype is "@ = @"; list of values as input and list of values as output.

       The value '%' can be used for both arguments and return value to say that key/value pair
       style lists are used.

       Alternatively, individual positional arguments can be listed each represented by a letter:

       "i" input argument

       "o" output argument

       "O" both input and output argument

       If the return value prototype has "!" appended, then it signals that this function sets
       errno ($!) when it returns a false value.  The trace will display the current value of
       errno in that case.

       If the return value prototype looks like a variable name (with "$" prefix), and the
       function returns a blessed object, then the variable name will be used as prefix and the
       returned object automatically traced.

SEE ALSO

       Data::Dump

AUTHOR

       Copyright 2009 Gisle Aas.

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.