%YAML 1.1
%TAG ! !VeryShiny::
--- !Talk
- |
  SET-TIMER::5
  OH HAI
- my name
- |
  [[PRE:
  NUFFIN
  ]]
  @nothingmuch
  Yuval Kogman
- http://blog.woobling.org/
- iron man
- please join
- just blog
- anyway
- exceptions in Perl
- throw
- !Code die "foo"
- !Code die $object
- catch
- !Code eval { }
- !Code $@
- but
- !Code eval
- is
- EVIL
- why?
- problem
- !Code |
  eval {
      doesn::t_die();
  };
- no error
- |
  clobbers
  [[PRE:
  $@
  ]]
- !Code $@ = ""
- !Code |
  sub DESTROY {
      eval { ... };
  }
- solution
- !Code local $@;
- problem
- |
  [[PRE:
  local
  ]]
  breaks
  [[PRE:
  die
  ]]
- "can't rethrow"
- !Code |
  sub die {
      $@ = $_[0];
      goto end_of_eval;
  }
- !Code |
  {
      local $@;
      die "foo";
  }
- !Code |
  {
      local $@;
      $@ = "foo";
  }
- no more error
- solution
- !Code |
  my $error;
 
  {
      local $@;
      eval { ... };
      $error = $@;
  }

  if ( ... ) {
      die $error; # rethrow
  }
- problem
- !Code if ( $@ )
- !Code DESTROY
- !Code |
  eval {
      my $evil = ...;
      die "foo";
  }
  
  if ( $@ ) { ... }
- !Code |
  die "foo";
  ...
  $evil->DESTROY();
  ...
  if ( $@ ) { ... }
- !Code |
  $@ = "foo";
  ...
  eval { };
  ...
  if ( $@ ) { ... }
- !Code |
  $@ = "foo";
  ...
  $@ = "";
  ...
  if ( $@ ) { ... }
- partial solution
- !Code |
  my $ok = eval {
      ...;
      return 1;
  }
- failure detected
- |
  but no
  [[PRE:
  $@
  ]]
- oh well
- "can't win em all"
- combined solution
- every time
- instead of
- !Code |
  my $value = eval {
      ...
  };

  if ( $@ ) {
      warn $@;
  } else {
      return $value;
  }
- !Code |
  local $@;

  my $value = eval {
      ...
  };

  if ( $@ ) {
      warn $@;
  } else {
      return $value;
  }
- !Code |
  my ( $error, $value );

  {
      local $@;
  
      $value = eval { ... };

      $error = $@;
  }

  if ( $error ) {
      warn $error;
  } else {
      return $value;
  }
- !Code |
  my ( $error, $failed, $value );

  {
      local $@;
  
      $failed = not eval {

          $value = ...; 
    
          return 1;
      };
  
      $error = $@;
  }

  if ( $failed ) {
      warn $error;
  } else {
      return $value;
  }
- !Code |
  my ( $error, $failed, @ret );

  my $wantarray = wantarray;

  {
      local $@;
  
      $failed = not eval {
  
          # note code duplication
          if ( $wantarray ) {
              @ret = ...;
          } elsif ( defined $wantarray ) {
              $ret[0] = ...;
          } else {
              ...;
          }
    
          return 1;
      };
  
      $error = $@;
  }

  if ( $failed ) {
      warn $error;
  } else {
      return $wantarray ? @value : $ret[0];
  }
- every time
- every f*%#ing time?!
- yuck
- solution for solution
- !Code Try::Tiny
- instead of
- !Code |
  my $value = eval {
      ...
  };

  if ( $@ ) {
      warn $@;
  } else {
      return $value;
  }
- !Code |
  try {
      ...
  } catch {
      warn $_;
  };
- polite
- defensive
- minimal
- 0 deps
- 5.005_04 compatible
- no catch sugar
- but
- !Code use 5.010;
- !Code |
  try {
      require Foo;
  } catch {
      when ( /Can't locate Foo\.pm in \@INC/ ) { }
      default { die $_ }
  };
- like Perl 6
- bonus
- !Code autodie
- smartmatch friendly
- want more syntax?
- !Code TryCatch
- MOAR AWESOME
- !Code Devel::Declare
- !Code MooseX::Method::Signatures
- not minimal
- "can't use everywhere"
- |
  but
  [[PRE:
  Try::Tiny
  ]]
  can be
- "don't be evil"
- Thank you!