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Take control

Take control. Introductie in het wijzigen van standaard Perl gedrag. use Workshop::Perl::Dutch 5; date( '2008-02-29' ); author( abeltje => 'Abe Timmerman' );. Technieken. overload tie CORE::GLOBAL Attribute::Handlers. overload gebruikers?. overload. stringify String functies Numify

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Take control

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  1. Take control Introductie in het wijzigen van standaard Perl gedrag use Workshop::Perl::Dutch 5; date( '2008-02-29' ); author( abeltje => 'Abe Timmerman' );

  2. Technieken • overload • tie • CORE::GLOBAL • Attribute::Handlers Take control

  3. overload gebruikers? Take control

  4. overload • stringify • String functies • Numify • Rekenkundige bewerkingen • Rekenkundige functies • overload::constant() Take control

  5. overload API • Operator overloading met sub • Unary operators: • 1 argument • Binary operators • 3 argumenten • 1ste altijd een object • 2de object of constante • 3de geeft aan of 1ste en 2de zijn verwisseld Take control

  6. Coords.pm package Coords; sub new { my( $class, $x, $y ) = @_; bless { _x => $x || 0, _y => $y || 0 }, $class; } sub move { my( $self, $dx, $dy ) = @_; ref $dx eq __PACKAGE__ and ( $dx, $dy ) = ( $dx->{_x}, $dx->{_y} ); $self->{_x} += $dx; $self->{_y} += $dy; return $self; } sub as_string { my( $self ) = @_; return sprintf "(%d, %d)", $self->{_x}, $self->{_y}; } Take control

  7. Coords.pm package Coords; use overload q{""} => \&as_string, fallback => 1; sub new { my( $class, $x, $y ) = @_; bless { _x => $x || 0, _y => $y || 0 }, $class; } sub move { my( $self, $dx, $dy ) = @_; ref $dx eq __PACKAGE__ and ( $dx, $dy ) = ( $dx->{_x}, $dx->{_y} ); $self->{_x} += $dx; $self->{_y} += $dy; return $self; } sub as_string { my( $self ) = @_; return sprintf "(%d, %d)", $self->{_x}, $self->{_y}; } Take control

  8. Testing Coords.pm use Test::More 'no_plan'; my $c = Coords->new( 150, 150 ); is $c, $c->as_string, "overloaded stringify: $c"; $c->move( -50, 50 ); is $c, "(100, 200)", "->move(-50,50): $c"; my $m = Coords->new( 50, -50 ); $c->move( $m ); is $c, "(150, 150)", "->move$m: $c"; # overload/coords/1fase/ -> prove -lv t/*.t Take control

  9. Using '+' to move use Test::More 'no_plan'; my $c1 = Coords->new( 150, 150 ); is $c1, $c1->as_string, "overloaded stringify: $c1"; my $c2 = Coords->new( -50, 50 ); is $c2, $c2->as_string, "overloaded stringify: $c2"; my $r2 = $c1 + $c2; isa_ok $r2, 'Coords'; is $r2, "(100, 200)", "overloaded addition: $r2"; Take control

  10. Using '+' to move use Test::More 'no_plan'; my $c1 = Coords->new( 150, 150 ); is $c1, $c1->as_string, "overloaded stringify: $c1"; my $c2 = Coords->new( -50, 50 ); is $c2, $c2->as_string, "overloaded stringify: $c2"; my $r1 = $c1->copy; isa_ok $r1, 'Coords'; is $r1, $c1, "->copy: $r1"; $r1->move( $c2 ); is $r1, "(100, 200)", "->move$c2: $r1"; my $r2 = $c1 + $c2; isa_ok $r2, 'Coords'; is $r2, "(100, 200)", "overloaded addition: $r2"; Take control

  11. Using '+' to move package Coords; use overload q{""} => \&as_string, fallback => 1; sub new { my( $class, $x, $y ) = @_; bless { _x => $x || 0, _y => $y || 0 }, $class; } sub copy { return bless { _x => $_[0]->{_x}, _y => $_[0]->{_y} }, ref $_[0]; } sub move { my( $self, $dx, $dy ) = @_; ref $dx and ( $dx, $dy ) = ( $dx->{_x}, $dx->{_y} ); $self->{_x} += $dx; $self->{_y} += $dy; return $self; } sub as_string { my( $self ) = @_; return sprintf "(%d, %d)", $self->{_x}, $self->{_y}; } Take control

  12. Using '+' to move package Coords; use overload q{""} => \&as_string, q{+} => \&add_move, fallback => 1; sub new { my( $class, $x, $y ) = @_; bless { _x => $x || 0, _y => $y || 0 }, $class; } sub copy { return bless { _x => $_[0]->{_x}, _y => $_[0]->{_y} }, ref $_[0]; } sub move { my( $self, $dx, $dy ) = @_; ref $dx and ( $dx, $dy ) = ( $dx->{_x}, $dx->{_y} ); $self->{_x} += $dx; $self->{_y} += $dy; return $self; } sub add_move { my( $a1, $a2 ) = @_; ref $a2 or die "Cannot move() with constants!"; $a1->copy->move( $a2 ); } sub as_string { my( $self ) = @_; return sprintf "(%d, %d)", $self->{_x}, $self->{_y}; } Take control

  13. Meer informatie • perldoc overload Take control

  14. tie() gebruikers? Take control

  15. tie() • Geef een object de interface van een Perl variabele type • Mogelijke typen: • Scalar • Array • Hash • Handle • Toegang tot het onderliggende object met behulp van tied() Take control

  16. TIEARRAY API • API: • TIEARRAY constructor • FETCH, STORE • FETCHSIZE, STORESIZE • CLEAR, EXTEND • EXISTS, DELETE • PUSH, POP, • SHIFT, UNSHIFT, SPLICE • UNTIE, DESTROY Take control

  17. TIEARRAY • Geef een object de interface van een array • In het voorbeeld: gebruik een scalar als array • substr() <-> push/pop/unshift/shift/slice Take control

  18. CharArray (src1) package CharArray; use warnings; use strict; sub TIEARRAY { my $class = shift; ref $_[0] or die "Usage: tie my @a, CharArray => \$scalar;"; bless $_[0], $class; } sub UNTIE { } sub FETCHSIZE { my $self = shift; defined $$self ? length( $$self ) : 0; } Take control

  19. CharArray (src2) sub FETCH { my( $self, $index ) = @_; $index > length $$self and $$self .= "" x ( 1 + $index - length $$self ); defined $$self ? substr $$self, $index, 1 : undef; } sub STORE { my( $self, $index, $value ) = @_; $index > length $$self and $$self .= "" x ( 1 + $index - length $$self ); substr $$self, $index, 1, $value; } sub PUSH { my $self = shift; $$self .= join "", @_; length $$self; } sub POP { my $self = shift; my $last = substr $$self, -1, 1; $$self = substr $$self, 0, length( $$self ) - 1; $last; } 1; Take control

  20. Testing CharArray.pm #! /usr/bin/perl use warnings; use strict; use Test::More 'no_plan'; use_ok 'CharArray'; { my $orig = 'value'; tie my @ca, 'CharArray', \$orig; is $ca[0], 'v', "First value '@ca' (${ tied( @ca ) })"; push @ca, 's'; is @ca, 6, "new length (${ tied( @ca ) })"; my $sorted = join "", sort @ca; is $sorted, 'aelsuv', "sorting the array works ($sorted)"; untie @ca; is $orig, 'values', "still the changed value in original ($orig)"; } # tie/array/ -> prove -lv t/*.t Take control

  21. TIEHANDLE API • API: • TIEHANDLE constructor • schrijven • PRINT, PRINTF • WRITE • lezen • READLINE • READ, GETC • CLOSE • UNTIE, DESTROY Take control

  22. TIEHANDLE (output) • Output • STDOUT, STDERR • Iedere andere GLOB • Methods: • TIEHANDLE() • PRINT • PRINTF Take control

  23. CatchOut.pm package CatchOut; use strict; use warnings; our $VERSION = 0.04; # tie *HANDLE, CatchOut => <\*TIEDHANDLE | \$buf> sub TIEHANDLE { my $class = shift; ref $_[0] eq __PACKAGE__ and return $_[0]; ref $_[0] eq 'SCALAR' or die "Usage:\n\ttie *HANDLE, CatchOut => <\*TIEDHANDLE | \$buf>"; bless $_[0], $class; } sub PRINT { my $self = shift; $$self .= join "", @_; } sub PRINTF { my $self = shift; my( $fmt, @args ) = @_; $$self .= sprintf $fmt, @args; } 1; Take control

  24. Testing CatchOut.pm #! perl use warnings; use strict; use Test::More 'no_plan'; use_ok 'CatchOut'; { my $outbuf; { local *OUT; tie *OUT, 'CatchOut', \$outbuf; print OUT "Testline\n"; untie *OUT; } is $outbuf, <<' __EOTEST__', "Caught the right output"; Testline __EOTEST__ } Take control

  25. TIEHANDLE (input) • Input • STDIN • Elke andere GLOB • Methods: • TIEHANDLE • READLINE Take control

  26. FeedIn.pm package FeedIn; use warnings; use strict; our $VERSION = 0.01; # tie *FH, FeedIn => $text; sub TIEHANDLE { my( $class, $store ) = @_; bless \$store, $class; } sub READLINE { my $self = shift; defined $$self or return; length $$self or return; if ( ! defined $/ ) { # slurp-mode my $all = $$self; $$self = undef; return $all; } if ( wantarray ) { my @lines = grep length $_ => $$self =~ m{(.*?(?:$/|\z))}sg; $$self = undef; return @lines; } else { return defined $$self =~ s{(.*?(?:$/|\z))}{}s ? $1 : undef; } } 1; Take control

  27. Testing FeedIn.pm #! perl use warnings; use strict; use Test::More 'no_plan'; use_ok 'FeedIn'; { local *IN; tie *IN, 'FeedIn', "regel 1\nregel 2"; my @line = <IN>; is scalar @line, 2, "2 lines in list-context"; is $line[0], "regel 1\n", "Read a line '$line[0]'"; is $line[1], "regel 2", "Read a line '$line[1]'"; } { local *IN; tie *IN, 'FeedIn', "regel 1\nregel 2"; my @line; while ( <IN> ) { push @line, $_ } is scalar @line, 2, "2 lines in list-context"; is $line[0], "regel 1\n", "Read a line '$line[0]'"; is $line[1], "regel 2", "Read a line '$line[1]'"; } { local *IN; tie *IN, 'FeedIn', "regel 1\nregel 2"; my $lines = do { local $/; <IN> }; is $lines, "regel 1\nregel 2", "Slurp-mode"; } Take control

  28. Meer informatie • perldoc perltie Take control

  29. CORE::GLOBAL gebruikers? Take control

  30. CORE::GLOBAL:: • Herdefinieren interne functies • prototype CORE:: • In de compileer fase (BEGIN) • Origineel altijd nog beschikbaar • CORE:: Take control

  31. CORE::GLOBAL::gmtime #! /usr/bin/perl use warnings; use strict; BEGIN { # 29 Feb 2008 12:00:00 GMT *CORE::GLOBAL::gmtime = sub (;$) { my $stamp = @_ ? $_[0] : 1204286400; CORE::gmtime( $stamp ); }; } printf "[ empty] %s\n", scalar gmtime( ); printf "[time()] %s\n", scalar gmtime( time ); Take control

  32. Een test case voor open() • Ik wil de volgende soort code testen: • open my $fh, '<', '/proc/cpuinfo' • Herdefinieer • CORE::GLOBAL::open • Gebruik een tied handle voor invoer • FeedIn.pm Take control

  33. MyOpen.pm package MyOpen; use warnings; use strict; our $VERSION = 0.01; sub core_open (*;$@) { my( $handle, $mode, $file, @list ) = @_; # make sure filehandles are in their own package my $pkg = caller; if ( defined $handle and !ref $handle ) { # bareword handle no strict 'refs'; $handle = *{ "$pkg\:\:$handle" }; } elsif ( !defined $handle ) { # undefined scalar, provide GLOBref $_[0] = $handle = do { no strict 'refs'; \*{ sprintf "%s::NH%d%d%d", $pkg, $$, time, rand 100 }; }; } # convert to two argumented open() defined $file and $mode .= " $file"; CORE::open( $handle, $mode ); }; # prepare open() for runtime override BEGIN { *CORE::GLOBAL::open = \&core_open } 1; Take control

  34. Testing MyOpen.pm #! perl use warnings; use strict; use Test::More 'no_plan'; BEGIN { use_ok 'MyOpen' } ok defined &CORE::GLOBAL::open, "CORE::GLOBAL::open() defined"; my $content; { CORE::open( my $fh, '<', $0 ) or die "Cannot CORE::open($0): $!"; isa_ok $fh, 'GLOB'; $content = do { local $/; <$fh> }; close $fh; like $content, qr/BEGIN { use_ok 'MyOpen' }/, "contains MyOpen"; } { open my $fh, '<', $0 or die "Cannot open($0): $!"; isa_ok $fh, 'GLOB'; my $file = do { local $/; <$fh> }; close $fh; is $file, $content, "contents still the same"; } Take control

  35. Bringing it togther (1/2) #! perl use warnings; use strict; use Test::More 'no_plan'; BEGIN { use_ok 'MyOpen' } ok defined &CORE::GLOBAL::open, "CORE::GLOBAL::open() defined"; use_ok 'FeedIn'; { no warnings 'redefine'; local *CORE::GLOBAL::open = \&tied_open; open my $fh, '<', $0 or die "Cannot tied_open($0): $!"; isa_ok tied( $fh ), 'FeedIn'; my $file = do { local $/; <$fh> }; close $fh; is $file, "open: $0", "tied_open() returned '$file'"; } Take control

  36. Bringing it together (2/2) sub tied_open (*;$@) { my( $handle, $mode, $file ) = @_; # make sure filehandles are in their own package my $pkg = caller; if ( defined $handle and !ref $handle ) { # bareword handle no strict 'refs'; $handle = *{ "$pkg\:\:$handle" }; } elsif ( !defined $handle ) { # undefined scalar, provide a GLOB $_[0] = $handle = do { no strict 'refs'; *{ sprintf "%s::NH%d%d%d", $pkg, $$, time, rand 100 }; }; } # convert to two argumented open() defined $file and $mode .= " $file"; # do the magic-tie for open "< $0" or pass to CORE::open() if ( $mode =~ m/^(?:<\s*)?($0)/ ) { tie $handle, FeedIn => "open: $1"; } else { CORE::open( $handle, $mode ); } } Take control

  37. Meer informatie • perldoc perlsub Take control

  38. Attribute::Handler gebruikers? Take control

  39. Attribute::Handlers • Perl heeft syntax voor attributes • :my_attribute(data) • Perl heeft twee geïmplementeerde attributes • :lvalue • :ATTR • Via :ATTR is de attribute implementatie uit te breiden • Een attribute is een sub met die naam die het :ATTR attribute heeft Take control

  40. Types voor een attribute • Deze typen kunnen een attribute krijgen • SCALAR • ARRAY • HASH • CODE (sub) Take control

  41. Aandachtspunten • De handler sub moet bekend zijn in de aanroepende namespace • use base • Declareer in UNIVERSAL:: • Argumenten aan de handler sub • Aanroepende package • Referentie naar de symbol table (CODE) • Referentie naar de variabele/code • Attribute naam • Data die aan het attribute wordt mee gegeven • Fase voor de handler (BEGIN,CHECK,INIT,END) Take control

  42. Een attribute voor tie() package Tie_OddEven; use strict; use warnings; our $VERSION = 0.01; use Attribute::Handlers; sub OddEven :ATTR(SCALAR) { my( $pkg, $symbol, $referent, $attr, $data ) = @_; tie $$referent, __PACKAGE__, $data; } sub TIESCALAR { my $class = shift; bless \(my $self = shift), $class; } sub FETCH { my $self = shift; return $$self % 2 == 0 ? 'even' : 'odd'; } sub STORE { my $self = shift; $$self = shift; } 1; Take control

  43. Voorbeeld code voor gebruik #! /usr/bin/perl use warnings; use strict; use lib 'lib'; use Tie_OddEven; tie my $oe, Tie_OddEven => 0; while ( 1 ) { print "Number: "; chomp( my $input = <> ); last unless $input =~ /^-?\d+$/; $oe = $input; printf "$input is $oe (%d)\n", ${ tied $oe }; } Take control

  44. Voorbeeld code voor gebruik #! /usr/bin/perl use warnings; use strict; use lib 'lib'; use base 'Tie_OddEven'; my $oe :OddEven(0); while ( 1 ) { print "Number: "; chomp( my $input = <> ); last unless $input =~ /^-?\d+$/; $oe = $input; printf "$input is $oe (%d)\n", ${ tied $oe }; } Take control

  45. Oorspronkelijke attribute package Tie_OddEven; use strict; use warnings; our $VERSION = 0.01; use Attribute::Handlers; sub OddEven :ATTR(SCALAR) { my( $pkg, $symbol, $referent, $attr, $data ) = @_; tie $$referent, __PACKAGE__, $data; } sub TIESCALAR { my $class = shift; bless \(my $self = shift), $class; } sub FETCH { my $self = shift; return $$self % 2 == 0 ? 'even' : 'odd'; } sub STORE { my $self = shift; $$self = shift; } 1; Take control

  46. Een UNIVERSAL:: attribute package Universal_OddEven; use strict; use warnings; our $VERSION = 0.01; use Attribute::Handlers; sub UNIVERSAL::OddEven :ATTR(SCALAR) { my( $pkg, $symbol, $referent, $attr, $data ) = @_; tie $$referent, __PACKAGE__, $data; } sub TIESCALAR { my $class = shift; bless \(my $self = shift), $class; } sub FETCH { my $self = shift; return $$self % 2 == 0 ? 'even' : 'odd'; } sub STORE { my $self = shift; $$self = shift; } 1; Take control

  47. Oorspronkelijke voorbeeld #! /usr/bin/perl use warnings; use strict; use lib 'lib'; use base 'Tie_OddEven'; my $oe :OddEven(0); while ( 1 ) { print "Number: "; chomp( my $input = <> ); last unless $input =~ /^-?\d+$/; $oe = $input; printf "$input is $oe (%d)\n", ${ tied $oe }; } Take control

  48. Gebruik UNIVERSAL attribute #! /usr/bin/perl use warnings; use strict; use lib 'lib'; use Universal_OddEven; my $oe :OddEven(0); while ( 1 ) { print "Number: "; chomp( my $input = <> ); last unless $input =~ /^-?\d+$/; $oe = $input; printf "$input is $oe (%d)\n", ${ tied $oe }; } Take control

  49. Oorspronkelijke attribute package Tie_OddEven; use strict; use warnings; our $VERSION = 0.01; use Attribute::Handlers; sub OddEven :ATTR(SCALAR) { my( $pkg, $symbol, $referent, $attr, $data ) = @_; tie $$referent, __PACKAGE__, $data; } sub TIESCALAR { my $class = shift; bless \(my $self = shift), $class; } sub FETCH { my $self = shift; return $$self % 2 == 0 ? 'even' : 'odd'; } sub STORE { my $self = shift; $$self = shift; } 1; Take control

  50. Een attribute en autotie package Auto_OddEven; use strict; use warnings; our $VERSION = 0.01; use Attribute::Handlers autotie => { '__CALLER__::OddEven' => __PACKAGE__ }; sub TIESCALAR { my $class = shift; bless \(my $self = shift), $class; } sub FETCH { my $self = shift; return $$self % 2 == 0 ? 'even' : 'odd'; } sub STORE { my $self = shift; $$self = shift; } 1; Take control

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