{ 

 local %ENV; 

 [[..do your own fancy %ENV manipulation here..] 

 } 

 [[..normal %ENV behavior here..] 

 It's also worth taking a moment to explain what happens when you localize a member of a composite type (i.e. an array or hash element). In this case, the element is localized ''by name''. This means that when the scope of the local() ends, the saved value will be restored to the hash element whose key was named in the local(), or the array element whose index was named in the local(). If that element was deleted while the local() was in effect (e.g. by a delete() from a hash or a shift() of an array), it will spring back into existence, possibly extending an array and filling in the skipped elements with undef. For instance, if you say 

 but our REGlob doesn't. Indeed, many perl built-in 

 have such context sensitive behaviors, and these must be 

 adequately supported by a properly written override. For a 

 fully functional example of overriding glob, study 

 library. 

  

  

 __Autoloading__ 

 requested subroutine using ''eval()'', then execute that 

 subroutine using a special form of ''goto()'' that erases 

 the stack frame of the AUTOLOAD routine without a 

 trace. (See the source to the standard module documented in 

 can also just emulate the routine and never define it. For 

 example, let's pretend that a function that wasn't defined 

 should just invoke system with those arguments. All 

 you'd do is: 

 A more complete example of this is the standard Shell module, which can treat undefined subroutine calls as calls to external programs. 

  

  

 Mechanisms are available to help modules writers split their 

 on adding C functions to Perl code in perlxs. 

  

  

 __Subroutine Attributes__