Recently I was looking the module Error and saw a syntax that I never have used. First when we look the interface of the module we think that it uses a filter to enable the try {...} catch foo {} syntax, but not, it just declare the subs try and catch with a prototype that indicates that it will receive a code and other stuffs.

So take a look in this code: 


sub try (&;@_) {
  print "try>> @_\n" ;
}
         
sub CLASS::catch {
  print "catch>> @_\n" ;
  return( 'catch' , @_ ) ;
}

sub with (&;$) {
  print "with>> @_\n" ;
  return( 'with' , @_ ) ;
}

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Now that we have declared our "new syntax", we can use in this way: 
  try {
    print "test\n" ;
  }
  catch CLASS with {
    print "alert\n" ;
  } ;

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And the output is: 
with>> CODE(0x1a72f20)
catch>> CLASS with CODE(0x1a72f20)
try>> CODE(0x1a72c5c) catch CLASS with CODE(0x1a72f20)

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What I'm wondering now is that this way to do things is documented, since I never saw this kind of code in other modules or at perldoc.

Ps: I think that the module Error should be a standart module. First because it really implement a good way to make/handle exceptions and it's pure Perl and standalone.

Graciliano M. P.
"Creativity is the expression of liberty".

In reply to Prototype "foo {...} bar {...}" is documented? by gmpassos

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