Section: User Contributed Perl Documentation (3)
Updated: 2004-04-06
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LWP::Debug - debug routines for the libwww-perl library  


 use LWP::Debug qw(+ -conns);

 # Used internally in the library
 LWP::Debug::debug('url ok');
 LWP::Debug::conns("read $n bytes: $data");



LWP::Debug provides tracing facilities. The trace(), debug() and conns() function are called within the library and they log information at increasing levels of detail. Which level of detail is actually printed is controlled with the "level()" function.

The following functions are available:

The "level()" function controls the level of detail being logged. Passing '+' or '-' indicates full and no logging respectively. Individual levels can switched on and of by passing the name of the level with a '+' or '-' prepended. The levels are:

  trace   : trace function calls
  debug   : print debug messages
  conns   : show all data transfered over the connections

The LWP::Debug module provide a special import() method that allows you to pass the level() arguments with initial use statement. If a use argument start with '+' or '-' then it is passed to the level function, else the name is exported as usual. The following two statements are thus equivalent (if you ignore that the second pollutes your namespace):

  use LWP::Debug qw(+);
  use LWP::Debug qw(level); level('+');

The "trace()" function is used for tracing function calls. The package and calling subroutine name is printed along with the passed argument. This should be called at the start of every major function.
The "debug()" function is used for high-granularity reporting of state in functions.
The "conns()" function is used to show data being transferred over the connections. This may generate considerable output.




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