Re: [perl #78112] [BUG] Null PMC access when using placeholder parameter in rhs of attribute assignment in class declaration in Rakudo
std seems to complain that the placeholder variables are not valid here.
Maybe we need more clarification on whether this should work or not.
ash_ std: class A {has $.a = $^b + 1 }; say A.new(1).a
p6eval std 237d266: OUTPUT«[31m===[0mSORRY![31m===[0mPlaceholder variable
$^b may not be used here because the surrounding package block takes no
signature at /tmp/Fx9q_bkcz8 line 1:-- [32mclass A {has $.a =
$^b[33m⏏[31m + 1}; say A.new(1).a
--
John Harrison
On Tue, Sep 28, 2010 at 5:34 PM, Carl Mäsak perl6-bugs-follo...@perl.orgwrote:
# New Ticket Created by Carl Mäsak
# Please include the string: [perl #78112]
# in the subject line of all future correspondence about this issue.
# URL: http://rt.perl.org/rt3/Ticket/Display.html?id=78112
hudnix rakudo: class A {has $.a = $^b + 1;has $.b = $^a }; say
A.new(1,2).a
p6eval rakudo 624188: OUTPUT«Null PMC access in type() [...]
* masak submits rakudobug
masak rakudo: class A { has $.a = $^b }; A.new
p6eval rakudo 624188: OUTPUT«Null PMC access in isa_pmc() [...]
Re: [perl #78156] AutoReply: [BUG] Null PMC access on does Callable
This appears to only happen on mutli subs but I am still looking for other
causes.
--
John Harrison
On Fri, Oct 1, 2010 at 11:11 AM, perl6 via RT
perl6-bugs-follo...@perl.orgwrote:
Greetings,
This message has been automatically generated in response to the
creation of a trouble ticket regarding:
[BUG] Null PMC access on does Callable,
a summary of which appears below.
There is no need to reply to this message right now. Your ticket has been
assigned an ID of [perl #78156].
Please include the string:
[perl #78156]
in the subject line of all future correspondence about this issue. To do
so,
you may reply to this message.
Thank you,
perl6-bugs-follo...@perl.org
-
Some subs can 'does Callable' while other return Null PMC access errors.
TimToady rakudo: say print does Callable
p6eval rakudo 8827d0: OUTPUT«Null PMC access in clone() in
'infix:does' at line 37 in 'infix:does' at line 537:CORE.setting in
main program body at line 22:/tmp/NXqor71nBI»
TimToady oo
TimToady rakudo: sub foo {}; say foo does Callable
p6eval rakudo 8827d0: OUTPUT«foo»
--
John Harrison
Re: slurpy hash
One thing also worth noting is that $1 is an alias to $/[1].
perl6
my $1 = 2; say $1;
2
my $1 = 2; say $/[1];
2
Also, $foo is an alias to $/foo. This would make them rather difficult
to use in parameters, IMO.
--
John Harrison
On Wed, Aug 18, 2010 at 3:12 AM, Moritz Lenz mor...@faui2k3.org wrote:
Am 18.08.2010 01:33, schrieb Darren Duncan:
David H. Adler wrote:
Hm. So how are valid parameter names defined? Identifiers in perl6 seem
to be composed of letters, digits and underscores (and hyphens and
apostrophes between letters).
That's correct.
Are parameter names defined differently?
Yes and no. If you want to use the normal syntax like this:
sub f(:$named-name) { ... }
your indeed limited to identifiers. But with slurpy hashes you can use any
key, really:
sub f(*%h) {
say %h{ '++' };
}
f(|{ '++' = 'non-identifier names work'})
However this is rather clumsy, and should be reserved for interoperation
with other languages which have different ideas of what an identifier is.
You certainly seem to be able to declare a variable $1.
If Rakudo allows that, it's a bug. STD.pm6, Larry's Perl 6 grammar, says
Can't declare a numeric variable about it.
I believe that Perl 6 identifiers can be any string at all, but that
then they have to appear quoted in the general case;
the above
restriction just refers to the common case of unquoted identifiers. This
said, I'm not sure yet what the syntax is for quoting identifiers. --
This distinction is new to me. For identifier means what you call
unquoted identifier, and my reading of the synopsis so far hasn't
contradicted that unerstanding in any way.
But that's really a question of how you call stuff - your explanation is
correct, as I demonstrated above.
Cheers,
Moritz
Re: Methodicals: A better way to monkey type
Ruby has a similar functionality that lets you define methods on an instance
object. Really, its how class methods are specified, you just put the class
name as the name of the object. Here is an example:
a = Object.new
def a.foo
puts foo and #{self}
end
They will stay on the object as long as the object exists. So, if its a
scoped variable, it will go away when you leave the scope.
--
John Harrison
On Wed, Apr 21, 2010 at 7:49 AM, Andrew Whitworth wknight8...@gmail.comwrote:
This idea strikes me as being extremely similar to C#'s extension
methods, a feature that I've found to be particularly beneficial in
many cases. The fact that these methodicals are lexically-scoped is
especially nice, and the fact that they can be applied post-hoc to
arbitrary data items that have no prior support for them (like Parrot
objects) would be very nice to have on Parrot in particular where
language interoperation could be a big deal in the future.
+1
--Andrew Whitworth
On Wed, Apr 21, 2010 at 3:16 AM, Stefan O'Rear stefa...@cox.net wrote:
(The following describes a proposed extension to Perl 6, methodical
scoped
operators or methodicals for short. It is written in the present tense
for
simplicity but should be understood as the future conditional.)
Normally, when you write a method call, the definition of the method is
entirely in the domain of the receiver's class:
$object.make-me-a-sandwich; # $object gets to decide what this means
However, this is not always how things work.
$object.WHAT; # Larry says that WHAT should return the protoobject
WHAT, WHENCE, postcircumfix:[ ], and similar operators have semantics
(although not implementation) defined by the language itself. Currently,
Perl 6
fakes this by having all values inherit from Any or Mu or Cool, which
define
the basic, overridable versions of these method-like operators. This
cheat
actually works pretty well in a homogeneous environment, but it fails if
we have
to consider objects from outside Perl 6.
$parrot-array.WHAT; # Method WHAT not found for invocant of type ...
The problem here is that scopes are conflated - WHAT is defined by the
language, which is approximately a lexical scope, while methods on an
object
are in some entirely different scope.
A methodical is an operator which syntactically behaves as a method but
is
subject to scoping rules. Methodicals are defined using the ordinary
method
keyword, qualified with my or our. (TODO: This seems the most natural
syntax
to me, but it conflicts with existing usage. Which is more worth having
on
it?) Methodicals do not need to be declared in classes, but they should
generally have declared receiver types.
{
my method make-me-a-sandwich(Num:) { ... }
2.make-me-a-sandwich; # calls our method
ham.make-me-a-sandwich; # either an error, or method dispatch
}
2.make-ma-a-sandwich; # ordinary method dispatch
The primary use case for methodicals is naturally in the setting. Many
of the
methods which are currently defined on lower-level types could become
methodicals and they would be available on all values, in any code
compiled
within the Perl 6 setting, without polluting the referencing environments
of
non-Perl 6 code in the same object environment.
my method WHAT($thing) { ... }
Rakudo already uses something very much like an ad-hoc direct
implementation of
methodicals to handle postcircumfix operators.
Methodicals are also useful in user code where the most natural phrasing
of a
calculation is as a property of a system type, for instance from the
Mandelbrot
Advent example:
my method mandel(Complex:) {
my $z = 0i;
for ^$max-iterations {
$z = $z * $z + self;
return 1 if ($z.abs 2);
}
return 0;
}
Since methodicals do not pollute global referencing environments, and do
not
compromise encapsulation, MONKEY_TYPING is not needed here.
A methodical defined inside a class functions much like a private method.
There may be something interesting here, but I'm not entirely sure what.
There are two natural implementations of methodicals in terms of other
language
features. First, it is possible to treat methodicals as ordinary methods
(monkey typing under the hood), but with generated names; the true name
is
bound to the program name only within the correct scope. If possible,
the
methods should be treated as anonymous, accessible only though an opaque
name
object. Care must be taken to prevent incorrect exposure of private
fields and
methods.
Alternatively, a methodical can be desugared to a multi sub with the same
scope
as the methodical itself, changing statically named method calls into
calls to
the methodical. This gives reflection invisibility and privacy for free,
but
may require more work
Re: Symbol '$x' not predeclared in anonymous
Each line is executed independently. Local variables from 1 line of code will not persist between returns. Some things do persist though, classes for instance will persist, roles will persist, grammars will persist, but sub routines will not, neither will variables. I believe there are plans for some improvements, eventually, but right now its fairly simplistic. On Tue, Mar 9, 2010 at 11:42 AM, Kiffin Gish kiffin.g...@planet.nl wrote: I want to play around with perl6 and see what it can do. $ cd rakudo $ ./perl6 my $x = 8 say $x Symbol '$x' not predeclared in anonymous How can I define variables and use them later? -- Kiffin Gish kiffin.g...@planet.nl Gouda, The Netherlands -- John ash Harrison
Re: Custom errors on subsets?
Would it make sense to have the failure bound to the function parameter
rather than the subset? eg.:
sub foo (Str $name where { $_ ~~ :f } else { die Houston, we don't have a
file } ) { ... }
Just a thought...
On Tue, Jan 5, 2010 at 1:07 AM, Ovid
publiustemp-perl6langua...@yahoo.comwrote:
--- On Mon, 4/1/10, yary not@gmail.com wrote:
From: yary not@gmail.com
How about
multi sub foo(Any $name) { die Houston, we have a major
malfunction.}
Looks like tha would work, but it forces the developer to remember to write
this extra code every time they may have a constraint failure, if they
forget, we're back to the old, cryptic message. It would be much nicer to
be able to do this (psuedo-code, obviouly):
subset Filename of Str where { $_ ~~ :f }
:OnFail { No such file: '$_' }
subset Celsius of Num where { $_ = -273.15 }
:OnFail { Celsius temperature should be a Num = -273.15, not '$_' }
With something akin to that, developers won't have to write extra
boilerplate every time a constraint fails. Plus, the code is friendlier :)
Cheers,
Ovid
--
Buy the book - http://www.oreilly.com/catalog/perlhks/
Tech blog- http://use.perl.org/~Ovid/journal/
Twitter - http://twitter.com/OvidPerl
Official Perl 6 Wiki - http://www.perlfoundation.org/perl6
--
John ash Harrison
Re: Perl 6 IDEs
http://github.com/petdance/vim-perl has vim syntax highlighting for perl 6. 2009/12/7 Steffen Schwigon s...@renormalist.net Víctor A. Rodríguez (Bit-Man) vic...@bit-man.com.ar writes: Hi perlsixers, we've been working a bit on Perl 6 lately [1] and some work, even the basic coding, would be great if we use some IDE. I'm a regular Eclipse user and EPIC seems the natural choice for me, but it doesn't support Perl 6 (yet). Also tied to install Padre on top of Ubuntu but just went to nowhere :-P Did anyone tried any other Perl 6 aware IDE ?? There is a Perl6 aware cperl-mode.el for Emacs which works quite ok. Don't start a war on whether it's an IDE. I just wanted to mention it. Find it in the Pugs repository. Kind regards, Steffen -- Steffen Schwigon s...@renormalist.net -- John ash Harrison
