Perl 510 for People Who Arent Totally Insane 4609

8/8/2019 Perl 510 for People Who Arent Totally Insane 4609

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Perl 5.10insanefor people who are not


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Perl 5.10insanetotallyfor people who are not


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perl5100delta

5.10 isnt like 5.8.x


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perl5100delta


-features only get added in new 5.x releases


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perl5100delta


-features only get added in new 5.x releases

- its been 5 years since the last release (5.8)


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perl51000delta

5.10 is Way Cool


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5.10 is Way Cool

- no significant new features in Perl since 2002


8/184perl51000delta

5.10 is Way Cool


-

remember how bad you wanted to see Star

Wars: Episode 1?


9/184perl51000delta

5.10 is Way Cool


-


Wars: Episode 1?

- thats how excited you should be for 5.10


10/184perl51000delta

5.10 is Way Cool


-


Wars: Episode 1?

- thats how excited you should be for 5.10

-but it wont suck (no POD race scene)



Lexicascopasmartwhat?




- lexically scoped user pragmata!





-pluggable regex compilation engines!






- trie-based non-recursive pattern matching!


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perl51000delta




- trie-based non-recursive pattern matching!

-

thread-safe weak refkey hashes!


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perl51000delta

Yes, You Care

- Not everything in 5.10 is esoteric.


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perl51000delta

Yes, You Care


-Not everything in 5.10 is for gurus.


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perl51000delta

Yes, You Care



- Not everything in 5.10 is for C programmers.


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perl51000delta

Yes, You Care



- Not everything in 5.10 is for C programmers.

-

Not everything in 5.10 is super advanced.


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feature

First: A Warning


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feature

First: A Warning

- 5.10 is backwards compatible


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feature

First: A Warning


- but adds new keywords and operators


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feature

First: A Warning



-theyre not enabled by default


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feature

First: A Warning




- use feature mtfnpy;


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feature

First: A Warning





-

use 5.010;


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feature

First: A Warning





-

use 5.010;

- read the perldoc


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feature

First: A Warning





-

use 5.010;

- read the perldoc Im a per ldocref!


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feature

First: A Warning





-

use 5.010;

- read the perldoc


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say what


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perlfunc

-

new built-in, say

- its like print

- but it adds a newline for you

say $what


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perlfunc

say $what


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perlfunc

say $what

print Hello, world!\n;


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perlfunc

say $what


print $message\n;


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perlfunc

say $what


print $message\n;

print $_\n for @lines;


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perlfunc

say $what


print $message\n;


say Hello, world!;


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perlfunc

say $what


print $message\n;


say Hello, world!;

say $message;


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perlfunc

say $what


print $message\n;


say Hello, world!;

say $message;

say for @lines;


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truth and definedness


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perlop



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perlop


sub record_sale {


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perlop


sub record_sale {my ($product, $amount) = @_;


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perlop



$amount ||= $product->cost;


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perlop




...


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perlop




...}


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perlop



$amount = defined $amount? $amount: $product->cost;

...}


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perlop




...}


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perlop




...}


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perlop

the new OR operator


$amount //= $product->cost;

...}


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perlop

the new OR operator

$setting = defined $given? $given: $default;


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perlop

the new OR operator

$setting = $given;unless (defined $setting) {$setting = $default;

}


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perlop

the new OR operator

$setting = $given || $default;


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perlop

the new OR operator

$setting = $given // $default;


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keeping state


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perlsub

$lines_left = 100;

sub read_line {die trial period expiredunless $lines_left-- > 0;

...}

State Variables


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perlsub

my $lines_left = 100;


...}

State Variables


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perlsub

{my $lines_left = 100;


...}}

State Variables


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perlsub

package Trial::Period;sub new {my ($class, $arg) = @_;my $guts = {lines_left => $arg->{lines},error_msg => $arg->{error},

};return bless $guts => $class;

}

sub consume_line {my ($self) = @_;$self->{lines_left}--;

}

sub lines_left {my ($self) = @_;return $self->{lines_left};

}

sub assert_lines_left {my ($self) = @_;unless ($self->lines_left) {die $self->{error_msg};

}}1;

State Variables

my $LINES = 100;my $ERROR = sorry, trial period over;my $TRIAL = Trial::Period->new({lines => $LINES,error => $ERROR,

});

sub read_line {$TRIAL->assert_lines_left;...

}


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perlsub

{my $lines_left = 100;


...}}

State Variables


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perlsub

sub read_line {

state $lines_left = 100;die trial period expiredunless $lines_left-- > 0;

...}

State Variables


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-x stacking


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perlfunc

if (-f $fileand -w $fileand -z $file

) {

unlink $file;}

Stackable File Tests


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perlfunc

if (-f $file and -w _ and -z _

) {unlink $file;

}



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perlfunc

if (-f -w -z $file) {unlink $file;

}



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smart matching


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perlsyn

Smart Matching


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perlsyn

Smart Matching

- a new kind of comparison operator


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perlsyn

Smart Matching


-its behavior depends on its inputs


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perlsyn

Smart Matching



- if these two things match...


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perlsyn

Smart Matching



- if these two things match...

-

hard to tell, easy to show...


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perlsyn

Smart Matching

if ($foo ~~ undef) { ... }


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perlsyn

Smart Matching

if ($foo ~~ undef) { ... }elsif ($foo ~~ @array) { ... }


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perlsyn

Smart Matching

if ($foo ~~ undef) { ... }elsif ($foo ~~ @array) { ... }elsif ($foo ~~ $code) { ... }


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perlsyn

Smart Matching

if ($foo ~~ undef) { ... }elsif ($foo ~~ @array) { ... }elsif ($foo ~~ $code) { ... }elsif ($foo ~~ %hash) { ... }


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perlsyn

Smart Matching

if ($foo ~~ undef) { ... }elsif ($foo ~~ @array) { ... }elsif ($foo ~~ $code) { ... }elsif ($foo ~~ %hash) { ... }elsif ($foo ~~ qr/re/) { ... }


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perlsyn

Smart Matching


elsif ($foo ~~ $bar) { ... }


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perlsyn

Smart Matching


elsif ($foo ~~ $bar) { ... }else { ... }


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perlsyn

Smart Matching

given ($foo) {when (undef) { ... }when (@array) { ... }when ($code) { ... }when (%hash) { ... }when (qr/re/) { ... }

when ($bar) { ... }default { ... }}


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perlsyn

Smart Matching




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perlsyn

Smart Matching

if ($foo ~~ undef) { ... }elsif ($foo ~~ $array) { ... }elsif ($foo ~~ $code) { ... }elsif ($foo ~~ $hash) { ... }elsif ($foo ~~ qr/re/) { ... }



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perlsyn

Smart Matching

my $test;


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perlsyn

Smart Matching

given ($foo) {when (undef) { ... }when ($aref) { ... }when ($code) { ... }when ($href) { ... }when ($regex) { ... }

when ($object) { ... }default { ... }}


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perlsyn

Smart Matching

given ($foo) {when ($test_1) { ... }when ($test_2) { ... }when ($test_3) { ... }when ($test_4) { ... }when ($test_5) { ... }

when ($test_6) { ... }default { ... }}


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perlsyn

Smart Matching


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perlsyn

Smart Matching

@want = @have->where($test)


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perlsyn

Smart Matching


@want = @have->where(sub{ })


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h


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perlsyn

Smart Matching


@want = @have->where(sub{ })

@want = @have->where(qr/.../sm)

@want = @have->where([ 1,2,3 ])

h


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perlsyn

Smart Matching


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S M h


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perlsyn

Smart Matching

sub where {my ($array, $test) = @_;


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S M h


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perlsyn

Smart Matching


if (ref $test eq ARRAY) {my %known = map {$_=>1} @$test;

S M h


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perlsyn

Smart Matching



return grep { $known{$_} } @$array;

S M h


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perlsyn

Smart Matching



return grep { $known{$_} } @$array;}

S M hi


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perlsyn

Smart Matching



return grep { $known{$_} } @$array;}if (ref $test eq Regexp) {

S M hi


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perlsyn

Smart Matching



return grep { $known{$_} } @$array;}if (ref $test eq Regexp) {return grep { $_ =~ $test } @$array;

S M hi


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perlsyn

Smart Matching




}

S M hi


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perlsyn

Smart Matching




}if (ref $test eq CODE) {

S M hi


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perlsyn

Smart Matching




}if (ref $test eq CODE) {return grep { $test->($_) } @$array;

S M hi


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perlsyn

Smart Matching





}

S M hi


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perlsyn

Smart Matching





}

die invalid test

S M hi


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perlsyn

Smart Matching





}

die invalid test}

S M hi


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perlsyn

Smart Matching

sub where {my ($array, $test) = @_;grep { $_ ~~ $test } @$array;

}

S M hi


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perlsyn

Smart Matching

SmartMatch::Sugar

S t M t hi


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perlsyn

Smart Matching

@want = @have->where( hash )

SmartMatch::Sugar

S t M t hi


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perlsyn

Smart Matching


@want = @have->where( class )

SmartMatch::Sugar

S t M t hi


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perlsyn

Smart Matching


@want = @have->where( class )

@want = @have->where(isa(Foo))

SmartMatch::Sugar


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unknown undefined

B tt E M ( )


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perldiag

$str = Greetings, $name. Your lastlogin was $last. It is now $time.;

Better Error Message(s)

B tt E M ( )


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perldiag



Use of uninitialized value in

concatenation (.) or string athello.plx line 9.

B tt E M g ( )


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perldiag


Use of uninitialized value $time in

concatenation (.) or string athello.plx line 9.



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inside-out objects

Inside Out Objects


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Hash::Util::FieldHash

Inside-Out Objects

Inside Out Objects


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Inside-Out Objects

- traditional objects are a hashref

Inside Out Objects


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Inside-Out Objects


-

look up attrs in the obj itself by attr name

Inside Out Objects


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Inside-Out Objects


-

look up attrs in the obj itself by attr name- inside-out objects are content-free refs

Inside Out Objects


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Inside-Out Objects


-

look up attrs in the obj itself by attr name- inside-out objects are content-free refs

- look up attrs in an external hash by obj id


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Inside Out Objects


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Inside-Out Objects

sub size {my $self = shift;

if (@_) {return $self->{size} = shift;

} else {return $self->{size};

}}

Inside Out Objects


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Inside-Out Objects

my %size;sub size {

my $self = shift;

if (@_) {return $size{ $self } = shift;

} else {

return $size{ $self };}}

Inside Out Objects


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Inside-Out Objects

my %size;sub size {my $self = shift;my $id = refaddr $self;

if (@_) {return $size{ $id } = shift;

} else {

return $size{ $id };}

}


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Inside Out Objects


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Inside-Out Objectsmy %size;sub size {my $self = shift;my $id = refaddr $self;

if (@_) {return $size{ $id } = shift;

} else {return $size{ $id };

}}

sub DESTROY {my $id = refaddr $_[0];delete $size{ $id };

}

sub CLONE {my $class = shift;

my @properties = map { values %$_ }values %PROP_DATA_FOR;

for my $old_id ( keys %OBJ ) {

my $object = $OBJ{ $old_id };my $new_id = refaddr $object;

for my $prop ( @properties ) {next unless exists $prop->{ $old };$prop->{ $new } = $prop->{ $old };delete $prop->{ $old };

}

weaken ( $OBJ{ $new } = $object );delete $OBJ{ $old };

}}


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Field Hashes


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Field Hashes

Field Hashes


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Field Hashes

- theyre just like hashes

Field Hashes


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Field Hashes


- objects as keys become object ids

Field Hashes


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Field Hashes


- objects as keys become object ids

- but get destroyed and cloned

Field Hashes


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Field Hashes

my %size;sub size {

my $self = shift;


} else {


Field Hashes


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Field Hashes

fieldhash my %size;sub size {

my $self = shift;


} else {


Field Hashes


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Field Hashes

{fieldhash my %size;sub size {my $self = shift;if (@_) {return $size{ $self } = shift;} else {return $size{ $self };

}}

}

Field Hashes


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Field Hashes

sub size {my $self = shift;fieldhash state %size;


} else {



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Lexical Topic


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perlvar

for (@lines) {chomp;

next if /^#/;next unless length;s/a/b/;sanity_check;

say;}

Lexical Topic

Lexical Topic


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perlvar

Lexical Topic

for my $line (@lines) {chomp $line;

next if $line ~~ /^#/;next unless length $line;$line =~ s/a/b/;sanity_check($line);

say $line;}

Lexical Topic


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perlvar

for my $_ (@lines) {chomp;

next if /^#/;next unless length;s/a/b/;sanity_check;

say;}

Lexical Topic


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Regex


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named captures

Regex: Named Captures


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perlre




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perlre


- find matches by name, not position



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perlre


- find matches by name, not position

- avoid the dreaded $1


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perlre

# our hypothetical format

section:property = value




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perlre

$line ~~ /(\w+):(\w+) = (\w+)/;$name = $2;$value = $3;




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perlre

$lhs_re = qr/(\w+):(\w+)/;$rhs_re = qr/(\w+)/;

$line ~~ /$lhs_re = $rhs_re/;

$name = $2;

$value = $3;




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perlre

$line ~~ /$lhs_re = $rhs_re/;$name = $2;$value = $3;



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perlre

$lhs_re = qr/(\w+):(\w+)/;$rhs_re = qr/(\w+)/;

g p



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perlre

$lhs_re = qr/(\w+):(?\w+)/;$rhs_re = qr/(?\w+)/;

g p


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better backrefs

Regex: Backreference


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perlre

g

m{< (\w+) > .+ < /\1 > }x



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perlre

g

m{< (\w+) > .+ < /\1 > }x



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perlre

g

\10



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perlre

g

qr{(\d)\10}



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perlre

g

qr{ (\d) \1 0}x



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perlre

g

m{< (\w+) > .+ < /\1 > }x



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perlre

g

m{< (\w+) > .+ < /\g{1} > }x



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perlre

g

\10



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perlre

g

\g{10}



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perlre

g

qr{(\d)\10}


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perlop

if ($str =~ $wtf_re) {...}



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perlop

if ($str ~~ $wtf_re) {...}


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Alternate Regex Engines


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p rlr pi

-

lets you change how regex work



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p l pi

-

lets you change how regex work

- but not how you use them (=~, s///, etc)



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gi POSIX


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re::engine::POSIX

my $regex = qr{ ... };

my @files = $find->file->in( $root );

say for grep { slurp ~~ $re } @files;


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re::engine::POSIX

use re::engine::POSIX;

my $regex = qr{ ... };





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re::engine::POSIX

use re::engine::POSIX;

my $regex = qr{ ... }x;




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http://www.perl.org/get.html


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Perl 510 for People Who Arent Totally Insane 4609

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Transcript of Perl 510 for People Who Arent Totally Insane 4609