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


2/184

Perl 5.10insanetotallyfor people who are not


3/184

perl5100delta

5.10 isnt like 5.8.x


4/184

perl5100delta


-features only get added in new 5.x releases


5/184

perl5100delta


-features only get added in new 5.x releases

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


6/184

perl51000delta

5.10 is Way Cool


7/184perl51000delta

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!


15/184

perl51000delta




- trie-based non-recursive pattern matching!

-

thread-safe weak refkey hashes!


16/184


17/184

perl51000delta

Yes, You Care

- Not everything in 5.10 is esoteric.


18/184

perl51000delta

Yes, You Care


-Not everything in 5.10 is for gurus.


19/184

perl51000delta

Yes, You Care



- Not everything in 5.10 is for C programmers.


20/184

perl51000delta

Yes, You Care



- Not everything in 5.10 is for C programmers.

-

Not everything in 5.10 is super advanced.


21/184

feature

First: A Warning


22/184

feature

First: A Warning

- 5.10 is backwards compatible


23/184

feature

First: A Warning


- but adds new keywords and operators


24/184

feature

First: A Warning



-theyre not enabled by default


25/184

feature

First: A Warning




- use feature mtfnpy;


26/184

feature

First: A Warning





-

use 5.010;


27/184

feature

First: A Warning





-

use 5.010;

- read the perldoc


28/184

feature

First: A Warning





-

use 5.010;

- read the perldoc Im a per ldocref!


29/184

feature

First: A Warning





-

use 5.010;

- read the perldoc


30/184

say what


31/184

perlfunc

-

new built-in, say

- its like print

- but it adds a newline for you

say $what


32/184

perlfunc

say $what


33/184

perlfunc

say $what

print Hello, world!\n;


34/184

perlfunc

say $what


print $message\n;


35/184

perlfunc

say $what


print $message\n;

print $_\n for @lines;


36/184

perlfunc

say $what


print $message\n;


say Hello, world!;


37/184

perlfunc

say $what


print $message\n;


say Hello, world!;

say $message;


38/184

perlfunc

say $what


print $message\n;


say Hello, world!;

say $message;

say for @lines;


39/184

truth and definedness


40/184

perlop



41/184

perlop


sub record_sale {


42/184

perlop


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


43/184

perlop



$amount ||= $product->cost;


44/184

perlop




...


45/184

perlop




...}


46/184

perlop



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

...}


47/184

perlop




...}


48/184

perlop




...}


49/184

perlop

the new OR operator


$amount //= $product->cost;

...}


50/184

perlop

the new OR operator

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


51/184

perlop

the new OR operator

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

}


52/184

perlop

the new OR operator

$setting = $given || $default;


53/184

perlop

the new OR operator

$setting = $given // $default;


54/184

keeping state


55/184

perlsub

$lines_left = 100;

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

...}

State Variables


56/184

perlsub

my $lines_left = 100;


...}

State Variables


57/184

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


60/184

perlsub

sub read_line {

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

...}

State Variables


61/184

-x stacking


62/184

perlfunc

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

) {

unlink $file;}

Stackable File Tests


63/184

perlfunc

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

) {unlink $file;

}



64/184

perlfunc

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

}



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smart matching


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perlsyn

Smart Matching


67/184

perlsyn

Smart Matching

- a new kind of comparison operator


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perlsyn

Smart Matching


-its behavior depends on its inputs


69/184

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...


71/184


72/184

perlsyn

Smart Matching

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


73/184

perlsyn

Smart Matching

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


74/184

perlsyn

Smart Matching

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


75/184

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) { ... }


78/184

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




81/184

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;


83/184

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


86/184

perlsyn

Smart Matching

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


87/184

perlsyn

Smart Matching


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


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h


89/184

perlsyn

Smart Matching


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

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

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

h


90/184

perlsyn

Smart Matching


91/184

S M h


92/184

perlsyn

Smart Matching

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


93/184

S M h


94/184

perlsyn

Smart Matching


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

S M h


95/184

perlsyn

Smart Matching



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

S M h


96/184

perlsyn

Smart Matching



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

S M hi


97/184

perlsyn

Smart Matching



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

S M hi


98/184

perlsyn

Smart Matching



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

S M hi


99/184

perlsyn

Smart Matching




}

S M hi


100/184

perlsyn

Smart Matching




}if (ref $test eq CODE) {

S M hi


101/184

perlsyn

Smart Matching




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

S M hi


102/184

perlsyn

Smart Matching





}

S M hi


103/184

perlsyn

Smart Matching





}

die invalid test

S M hi


104/184

perlsyn

Smart Matching





}

die invalid test}

S M hi


105/184

perlsyn

Smart Matching

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

}

S M hi


106/184

perlsyn

Smart Matching

SmartMatch::Sugar

S t M t hi


107/184

perlsyn

Smart Matching

@want = @have->where( hash )

SmartMatch::Sugar

S t M t hi


108/184

perlsyn

Smart Matching


@want = @have->where( class )

SmartMatch::Sugar

S t M t hi


109/184

perlsyn

Smart Matching


@want = @have->where( class )

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

SmartMatch::Sugar


110/184

unknown undefined

B tt E M ( )


111/184

perldiag

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

Better Error Message(s)

B tt E M ( )


112/184

perldiag



Use of uninitialized value in

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

B tt E M g ( )


113/184

perldiag


Use of uninitialized value $time in

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



114/184

inside-out objects

Inside Out Objects


115/184

Hash::Util::FieldHash

Inside-Out Objects

Inside Out Objects


116/184


Inside-Out Objects

- traditional objects are a hashref

Inside Out Objects


117/184


Inside-Out Objects


-

look up attrs in the obj itself by attr name

Inside Out Objects


118/184


Inside-Out Objects


-

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

Inside Out Objects


119/184


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


120/184

Inside Out Objects


121/184


Inside-Out Objects

sub size {my $self = shift;

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

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

}}

Inside Out Objects


122/184


Inside-Out Objects

my %size;sub size {

my $self = shift;

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

} else {

return $size{ $self };}}

Inside Out Objects


123/184


Inside-Out Objects

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

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

} else {

return $size{ $id };}

}


124/184

Inside Out Objects


125/184


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 };

}}


126/184

Field Hashes


127/184


Field Hashes

Field Hashes


128/184


Field Hashes

- theyre just like hashes

Field Hashes


129/184


Field Hashes


- objects as keys become object ids

Field Hashes


130/184


Field Hashes


- objects as keys become object ids

- but get destroyed and cloned

Field Hashes


131/184


Field Hashes

my %size;sub size {

my $self = shift;


} else {


Field Hashes


132/184


Field Hashes

fieldhash my %size;sub size {

my $self = shift;


} else {


Field Hashes


133/184


Field Hashes

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

}}

}

Field Hashes


134/184


Field Hashes

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


} else {



135/184


136/184

Lexical Topic


137/184

perlvar

for (@lines) {chomp;

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

say;}

Lexical Topic

Lexical Topic


138/184

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


139/184

perlvar

for my $_ (@lines) {chomp;

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

say;}

Lexical Topic


140/184

Regex


141/184

named captures

Regex: Named Captures


142/184

perlre




143/184

perlre


- find matches by name, not position



144/184

perlre


- find matches by name, not position

- avoid the dreaded $1


145/184



146/184

perlre

# our hypothetical format

section:property = value




147/184

perlre

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




148/184

perlre

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

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

$name = $2;

$value = $3;




149/184

perlre

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



150/184



151/184

perlre

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

g p



152/184

perlre

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

g p


153/184

better backrefs

Regex: Backreference


154/184

perlre

g

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



155/184

perlre

g

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



156/184

perlre

g

\10



157/184

perlre

g

qr{(\d)\10}



158/184

perlre

g

qr{ (\d) \1 0}x



159/184

perlre

g

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



160/184

perlre

g

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



161/184

perlre

g

\10



162/184

perlre

g

\g{10}



163/184

perlre

g

qr{(\d)\10}


164/184


165/184


166/184


167/184



168/184

perlop

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



169/184

perlop

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


170/184


171/184


172/184

Alternate Regex Engines


173/184

p rlr pi

-

lets you change how regex work



174/184

p l pi

-

lets you change how regex work

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



175/184

gi POSIX


176/184



177/184

re::engine::POSIX

my $regex = qr{ ... };

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

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


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179/184


180/184



181/184

re::engine::POSIX

use re::engine::POSIX;

my $regex = qr{ ... };





182/184

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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Date post:	09-Apr-2018
Category:	Documents
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Perl 510 for People Who Arent Totally Insane 4609

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