Data::Dump::Trace(3)					User Contributed Perl Documentation				      Data::Dump::Trace(3)

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.

perl v5.16.2							    2009-03-06						      Data::Dump::Trace(3)