Beefy Boxes and Bandwidth Generously Provided by pair Networks
Do you know where your variables are?
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??
use v5.14; use JSON -convert_blessed_universally; use Test::More; package Foo { sub new { bless \@_ => shift } sub bar { return JSON::to_json(\@_, { convert_blessed => 1, canoni +cal => 1 }) } } package Oof { our @ISA = 'Foo'; sub bar { scalar reverse JSON::to_json(\@_, { convert_blessed => 1 +, canonical => 1 }) } } # You are no doubt familiar with these... my $obj = Foo->new(1); # calling a class method (a constructor) my $str = $obj->bar; # calling an object method is($str, '[[1]]', 'bar returned what we expected'); # Did you know you could do this? my $constructor = 'new'; my $method = 'bar'; $obj = Foo->$constructor(1); $str = $obj->$method; is($str, '[[1]]', 'bar returned what we expected'); # We can even use fully qualified names... $constructor = 'Foo::new'; $method = 'Oof::bar'; $obj = Foo->$constructor(1); $str = $obj->$method; is($str, ']]1[[', 'Oof::bar is the stringy reverse of Foo::bar'); # Or we can use coderefs $constructor = \&Foo::new; $method = \&Oof::bar; $obj = Foo->$constructor(1); $str = $obj->$method; is($str, ']]1[[', 'Oof::bar is the stringy reverse of Foo::bar'); # Now, what is the point of blessing things? We bless objects # so that when we call $object->method, Perl "knows" what # package to find the method in. # # But if we can use coderefs as if they were methods, then # Perl doesn't really need the object to be blessed... # $method = \&Oof::bar; $obj = [1, 2, 3]; # a plain arrayref $str = $obj->$method; is($str, ']]3,2,1[[', 'Can call coderef methods on unblessed things'); # It even works with undef $method = \&Oof::bar; $obj = undef; $str = $obj->$method; is($str, ']llun[', 'llun is null backwards'); # A pair of parentheses evaluates the empty list in list # context, but undef in scalar context. The arrow operator # imposes a scalar context on the left-hand side. $method = \&Oof::bar; $str = ()->$method; is($str, ']llun[', 'llun is null backwards'); # do{} with nothing inside the block returns undef $method = \&Oof::bar; $str = do{}->$method; is($str, ']llun[', 'llun is null backwards'); # More fun... $method = \&Foo::bar; $str = do { my $x = 1; my $y = 2; $x+$y }->$method(2,1); is($str, '[3,2,1]', 'more fun'); # This makes sense when you consider what comma does in scalar context +... $method = \&Foo::bar; $str = (5,4,3)->$method(2,1); is($str, '[3,2,1]', 'maybe counter-intuitive'); done_testing();
perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

In reply to Re^3: How to call a sub-routine ref by tobyink
in thread How to call a sub-routine ref by greengaroo

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others lurking in the Monastery: (4)
    As of 2014-10-02 03:43 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      What is your favourite meta-syntactic variable name?














      Results (46 votes), past polls