table of contents
| 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 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
| 2021-06-29 | perl v5.40.0 |