Provided by: libobject-pad-perl_0.61-1_amd64 
NAME
"Object::Pad" - a simple syntax for lexical field-based objects
SYNOPSIS
On perl version 5.26 onwards:
use v5.26;
use Object::Pad;
class Point {
has $x :param = 0;
has $y :param = 0;
method move ($dX, $dY) {
$x += $dX;
$y += $dY;
}
method describe () {
print "A point at ($x, $y)\n";
}
}
Point->new(x => 5, y => 10)->describe;
Or, for older perls that lack signatures:
use Object::Pad;
class Point {
has $x :param = 0;
has $y :param = 0;
method move {
my ($dX, $dY) = @_;
$x += $dX;
$y += $dY;
}
method describe {
print "A point at ($x, $y)\n";
}
}
Point->new(x => 5, y => 10)->describe;
DESCRIPTION
This module provides a simple syntax for creating object classes, which uses private variables that look
like lexicals as object member fields.
WARNING This module is still experimental. The parts that currently exist do seem to work reliably but
much of the design is still evolving, and many features and have yet to be implemented. I don't yet
guarantee I won't have to change existing details in order to continue its development. Feel free to try
it out in experimental or newly-developed code, but don't complain if a later version is incompatible
with your current code and you'll have to change it.
That all said, please do get in contact if you find the module overall useful. The more feedback you
provide in terms of what features you are using, what you find works, and what doesn't, will help the
ongoing development and hopefully eventual stability of the design. See the "FEEDBACK" section.
Automatic Construction
Classes are automatically provided with a constructor method, called "new", which helps create the object
instances. This may respond to passed arguments, automatically assigning values of fields, and invoking
other blocks of code provided by the class. It proceeds in the following stages:
The BUILDARGS phase
If the class provides a "BUILDARGS" class method, that is used to mangle the list of arguments before the
"BUILD" blocks are called. Note this must be a class method not an instance method (and so implemented
using "sub"). It should perform any "SUPER" chaining as may be required.
@args = $class->BUILDARGS( @_ )
Field assignment
If any field in the class has the ":param" attribute, then the constructor will expect to receive its
argmuents in an even-sized list of name/value pairs. This applies even to fields inherited from the
parent class or applied roles. It is therefore a good idea to shape the parameters to the constructor in
this way in roles, and in classes if you intend your class to be extended.
The constructor will also check for required parameters (these are all the parameters for fields that do
not have default initialisation expressions). If any of these are missing an exception is thrown.
The BUILD phase
As part of the construction process, the "BUILD" block of every component class will be invoked, passing
in the list of arguments the constructor was invoked with. Each class should perform its required setup
behaviour, but does not need to chain to the "SUPER" class first; this is handled automatically.
The ADJUST phase
Next, the "ADJUST" and "ADJUSTPARAMS" block of every component class is invoked. This happens after the
fields are assigned their initial values and the "BUILD" blocks have been run.
Note also that both "ADJUST" and "ADJUSTPARAMS" blocks happen at the same time, in declaration order. The
"ADJUSTPARAMS" blocks do not form their own separate phase.
The strict-checking phase
Finally, before the object is returned, if the ":strict(params)" class attribute is present, then the
constructor will throw an exception if there are any remaining named arguments left over after assigning
them to fields as per ":param" declarations, and running any "ADJUSTPARAMS" blocks.
KEYWORDS
class
class Name :ATTRS... {
...
}
class Name :ATTRS...;
Behaves similarly to the "package" keyword, but provides a package that defines a new class. Such a class
provides an automatic constructor method called "new".
As with "package", an optional block may be provided. If so, the contents of that block define the new
class and the preceding package continues afterwards. If not, it sets the class as the package context of
following keywords and definitions.
As with "package", an optional version declaration may be given. If so, this sets the value of the
package's $VERSION variable.
class Name VERSION { ... }
class Name VERSION;
A single superclass is supported by the keyword "isa"
Since version 0.41.
class Name isa BASECLASS {
...
}
class Name isa BASECLASS BASEVER {
...
}
Prior to version 0.41 this was called "extends", which is currently recognised as a compatibility
synonym. Both "extends" and "isa" keywords are now discouraged, in favour of the ":isa" attribute which
is preferred because it follows a more standard grammar without this special-case.
One or more roles can be composed into the class by the keyword "does"
Since version 0.41.
class Name does ROLE, ROLE,... {
...
}
Prior to version 0.41 this was called "implements", which is currently recognised as a compatibility
synonym. Both "implements" and "does" keywords are now discouraged, in favour of the ":does" attribute
which is preferred because it follows a more standard grammar without this special-case.
An optional list of attributes may be supplied in similar syntax as for subs or lexical variables. (These
are annotations about the class itself; the concept should not be confused with per-object-instance data,
which here is called "fields").
Whitespace is permitted within the value and is automatically trimmed, but as standard Perl parsing
rules, no space is permitted between the attribute's name and the open parenthesis of its value:
:attr( value here ) # is permitted
:attr (value here) # not permitted
The following class attributes are supported:
:isa
:isa(CLASS)
:isa(CLASS CLASSVER)
Since version 0.57.
Declares a superclass that this class extends. At most one superclass is supported.
If the package providing the superclass does not exist, an attempt is made to load it by code equivalent
to
require CLASS ();
and thus it must either already exist, or be locatable via the usual @INC mechanisms.
The superclass may or may not itself be implemented by "Object::Pad", but if it is not then see
"SUBCLASSING CLASSIC PERL CLASSES" for further detail on the semantics of how this operates.
An optional version check can also be supplied; it performs the equivalent of
BaseClass->VERSION( $ver )
:does
:does(ROLE)
:does(ROLE ROLEVER)
Since version 0.57.
Composes a role into the class; optionally requiring a version check on the role package. This is a newer
form of the "implements" and "does" keywords and should be preferred for new code.
Multiple roles can be composed by using multiple ":does" attributes, one per role.
The package will be loaded in a similar way to how the ":isa" attribute is handled.
:repr(TYPE)
Sets the representation type for instances of this class. Must be one of the following values:
:repr(native)
The native representation. This is an opaque representation type whose contents are not specified. It
only works for classes whose entire inheritence hierarchy is built only from classes based on
"Object::Pad".
:repr(HASH)
The representation will be a blessed hash reference. The instance data will be stored in an array
referenced by a key called "Object::Pad/slots", which is fairly unlikely to clash with existing storage
on the instance. No other keys will be used; they are available for implementions and subclasses to use.
The exact format of the value stored here is not specified and may change between module versions, though
it can be relied on to be well-behaved as some kind of perl data structure for purposes of modules like
Data::Dumper or serialisation into things like "YAML" or "JSON".
This representation type may be useful when converting existing classes into using "Object::Pad" where
there may be existing subclasses of it that presume a blessed hash for their own use.
:repr(magic)
The representation will use MAGIC to apply the instance data in a way that is invisible at the Perl
level, and shouldn't get in the way of other things the instance is doing even in XS modules.
This representation type is the only one that will work for subclassing existing classes that do not use
blessed hashes.
:repr(autoselect), :repr(default)
Since version 0.23.
This representation will select one of the representations above depending on what is best for the
situation. Classes not derived from a non-"Object::Pad" base class will pick "native", and classes
derived from non-"Object::Pad" bases will pick either the "HASH" or "magic" forms depending on whether
the instance is a blessed hash reference or some other kind.
This achieves the best combination of DWIM while still allowing the common forms of hash reference to be
inspected by "Data::Dumper", etc. This is the default representation type, and does not have to be
specifically requested.
:strict(params)
Since version 0.43.
Can only be applied to classes that contain no "BUILD" blocks. If set, then the constructor will complain
about any unrecognised named arguments passed to it (i.e. names that do not correspond to the ":param" of
any defined field and left unconsumed by any "ADJUSTPARAMS" block).
Since "BUILD" blocks can inspect the arguments arbitrarily, the presence of any such block means the
constructor cannot determine which named arguments are not recognised.
This attribute is a temporary stepping-stone for compatibility with existing code. It is recommended to
enable this whenever possible, as a later version of this module will likely perform this behaviour
unconditionally whenever no "BUILD" blocks are present.
role
role Name :ATTRS... {
...
}
role Name :ATTRS...;
Since version 0.32.
Similar to "class", but provides a package that defines a new role. A role acts simliar to a class in
some respects, and differently in others.
Like a class, a role can have a version, and named methods.
role Name VERSION {
method a { ... }
method b { ... }
}
A role does not provide a constructor, and instances cannot directly be constructed. A role cannot extend
a class.
A role can declare that it requires methods of given names from any class that implements the role.
role Name {
requires METHOD;
}
A role can provide instance fields. These are visible to any "BUILD" blocks or methods provided by that
role.
Since version 0.33.
role Name {
has $field;
BUILD { $field = "a value" }
method field { return $field }
}
Since version 0.57 a role can declare that it provides another role:
role Name :does(OTHERROLE) { ... }
role Name :does(OTHERROLE OTHERVER) { ... }
This will include all of the methods from the included role. Effectively this means that applying the
"outer" role to a class will imply applying the other role as well.
The following role attributes are supported:
:compat(invokable)
Since version 0.35.
Enables a form of backward-compatibility behaviour useful for gradually upgrading existing code from
classical Perl inheritance or mixins into using roles.
Normally, methods of a role cannot be directly invoked and the role must be applied to an
Object::Pad-based class in order to be used. This however presents a problem when gradually upgrading
existing code that already uses techniques like roles, multiple inheritance or mixins when that code may
be split across multiple distributions, or for some other reason cannot be upgraded all at once. Methods
within a role that has the ":compat(invokable)" attribute applied to it may be directly invoked on any
object instance. This allows the creation of a role that can still provide code for existing classes
written in classical Perl that has not yet been rewritten to use "Object::Pad".
The tradeoff is that a ":compat(invokable)" role may not create field data using the "has" keyword.
Whatever behaviours the role wishes to perform must be provided only by calling other methods on $self,
or perhaps by making assumptions about the representation type of instances.
It should be stressed again: This option is only intended for gradual upgrade of existing classical Perl
code into using "Object::Pad". When all existing code is using "Object::Pad" then this attribute can be
removed from the role.
has
has $var;
has @var;
has %var;
has $var :ATTR ATTR...;
has $var = EXPR;
has $var { BLOCK };
Declares that the instances of the class or role have a member field of the given name. This member field
will be accessible as a lexical variable within any "method" declarations in the class.
Array and hash members are permitted and behave as expected; you do not need to store references to
anonymous arrays or hashes.
Member fields are private to a class or role. They are not visible to users of the class, nor inherited
by subclasses nor any class that a role is applied to. In order to provide access to them a class may
wish to use "method" to create an accessor, or use the attributes such as ":reader" to get one generated.
A scalar field may provide a expression that gives an initialisation value, which will be assigned into
the field of every instance during the constructor before the "BUILD" blocks are invoked. Since version
0.29 this expression does not have to be a compiletime constant, though it is evaluated exactly once, at
runtime, after the class definition has been parsed. It is not evaluated individually for every object
instance of that class. Since version 0.54 this is also permitted on array and hash fields.
Field Initialiser Blocks
Since version 0.54 a deferred statement block is also permitted, on any field variable type. This is an
experimental feature that permits code to be executed as part of the instance constructor, rather than
running just once when the class is set up. Code in a field initialisation block is roughly equivalent to
being placed in a "BUILD" or "ADJUST" block.
Control flow that attempts to leave a field initialiser block is not permitted. This includes any
"return" expression, any "next/last/redo" outside of a loop, with a dynamically-calculated label
expression, or with a label that it doesn't appear in. "goto" statements are also currently forbidden,
though known-safe ones may be permitted in future.
Loop control expressions that are known at compiletime to affect a loop that they appear within are
permitted.
has $field { foreach(@list) { next; } } # this is fine
has $field { LOOP: while(1) { last LOOP; } } # this is fine too
The following field attributes are supported:
:reader, :reader(NAME)
Since version 0.27.
Generates a reader method to return the current value of the field. If no name is given, the name of the
field is used. A single prefix character "_" will be removed if present.
has $field :reader;
# equivalent to
has $field; method field { return $field }
Since version 0.55 these are permitted on any field type, but prior versions only allowed them on scalar
fields. The reader method behaves identically to how a lexical variable would behave in the same context;
namely returning a list of values from an array or key/value pairs from a hash when in list context, or
the number of items or keys when in scalar context.
has @items :reader;
foreach my $item ( $obj->items ) { ... } # iterates the list of items
my $count = $obj->items; # yields count of items
:writer, :writer(NAME)
Since version 0.27.
Generates a writer method to set a new value of the field from its arguments. If no name is given, the
name of the field is used prefixed by "set_". A single prefix character "_" will be removed if present.
has $field :writer;
# equivalent to
has $field; method set_field { $field = shift; return $self }
Since version 0.28 a generated writer method will return the object invocant itself, allowing a chaining
style.
$obj->set_x("x")
->set_y("y")
->set_z("z");
Since version 0.55 these are permitted on any field type, but prior versions only allowed them on scalar
fields. On arrays or hashes, the writer method takes a list of values to be assigned into the field,
completely replacing any values previously there.
:mutator, :mutator(NAME)
Since version 0.27.
Generates an lvalue mutator method to return or set the value of the field. These are only permitted for
scalar fields. If no name is given, the name of the field is used. A single prefix character "_" will be
removed if present.
has $field :mutator;
# equivalent to
has $field; method field :lvalue { $field }
Since version 0.28 all of these generated accessor methods will include argument checking similar to that
used by subroutine signatures, to ensure the correct number of arguments are passed - usually zero, but
exactly one in the case of a ":writer" method.
:accessor, :accessor(NAME)
Since version 0.53.
Generates a combined reader-writer accessor method to set or return the value of the field. These are
only permitted for scalar fields. If no name is given, the name of the field is used. A prefix character
"_" will be removed if present.
This method takes either zero or one additional arguments. If an argument is passed, the value of the
field is set from this argument (even if it is "undef"). If no argument is passed (i.e. "scalar @_" is
false) then the field is not modified. In either case, the value of the field is then returned.
has $field :accessor;
# equivalent to
has $field;
method field {
$field = shift if @_;
return $field;
}
:weak
Since version 0.44.
Generated code which sets the value of this field will weaken it if it contains a reference. This applies
to within the constructor if ":param" is given, and to a ":writer" accessor method. Note that this only
applies to automatically generated code; not normal code written in regular method bodies. If you assign
into the field variable you must remember to call "Scalar::Util::weaken" yourself.
:param, :param(NAME)
Since version 0.41.
Sets this field to be initialised automatically in the generated constructor. This is only permitted on
scalar fields. If no name is given, the name of the field is used. A single prefix character "_" will be
removed if present.
Any field that has ":param" but does not have a default initialisation expression or block becomes a
required argument to the constructor. Attempting to invoke the constructor without a named argument for
this will throw an exception. In order to make a parameter optional, make sure to give it a default
expression - even if that expression is "undef":
has $x :param; # this is required
has $z :param = undef; # this is optional
Any field that has a ":param" and an initialisation block will only run the code in the block if required
by the constructor. If a named parameter is passed to the constructor for this field, then its code block
will not be executed.
Values for fields are assigned by the constructor before any "BUILD" blocks are invoked.
method
method NAME {
...
}
method NAME (SIGNATURE) {
...
}
method NAME :ATTRS... {
...
}
method NAME;
Declares a new named method. This behaves similarly to the "sub" keyword, except that within the body of
the method all of the member fields are also accessible. In addition, the method body will have a lexical
called $self which contains the invocant object directly; it will already have been shifted from the @_
array.
If the method has no body and is given simply as a name, this declares a required method for a role. Such
a method must be provided by any class that implements the role. It will be a compiletime error to
combine the role with a class that does not provide this.
The "signatures" feature is automatically enabled for method declarations. In this case the signature
does not have to account for the invocant instance; that is handled directly.
method m ($one, $two) {
say "$self invokes method on one=$one two=$two";
}
...
$obj->m(1, 2);
A list of attributes may be supplied as for "sub". The most useful of these is ":lvalue", allowing easy
creation of read-write accessors for fields (but see also the ":reader", ":writer" and ":mutator" field
attributes).
class Counter {
has $count;
method count :lvalue { $count }
}
my $c = Counter->new;
$c->count++;
Every method automatically gets the ":method" attribute applied, which suppresses warnings about
ambiguous calls resolved to core functions if the name of a method matches a core function.
The following additional attributes are recognised by "Object::Pad" directly:
:override
Since version 0.29.
Marks that this method expects to override another of the same name from a superclass. It is an error at
compiletime if the superclass does not provide such a method.
method (lexical)
method $var { ... }
method $var :ATTRS... (SIGNATURE) { ... }
Since version 0.59.
Declares a new lexical method. Lexical methods are not visible via the package namespace, but instead are
stored directly in a lexical variable (with the same scoping rules as regular "my" variables). These can
be invoked by subsequent method code in the same block by using "$self->$var(...)" method call syntax.
class WithPrivate {
has $var;
# Lexical methods can still see instance fields as normal
method $inc_var { $var++; say "Var was incremented"; }
method $dec_var { $var--; say "Var was decremented"; }
method bump {
$self->$inc_var;
say "In the middle";
$self->$dec_var;
}
}
my $obj = WithPrivate->new;
$obj->bump;
# Neither $inc_var nor $dec_var are visible here
This effectively provides the ability to define private methods, as they are inaccessible from outside
the block that defines the class. In addition, there is no chance of a name collision because lexical
variables in different scopes are independent, even if they share the same name. This is particularly
useful in roles, to create internal helper methods without letting those methods be visible to callers,
or risking their names colliding with other named methods defined on the consuming class.
BUILD
BUILD {
...
}
BUILD (SIGNATURE) {
...
}
Since version 0.27.
Declares the builder block for this component class. A builder block may use subroutine signature syntax,
as for methods, to assist in unpacking its arguments. A build block is not a subroutine and thus is not
permitted to use subroutine attributes (for example ":lvalue").
Note that a "BUILD" block is a named phaser block and not a method. Attempts to create a method named
"BUILD" (i.e. with syntax "method BUILD {...}") will fail with a compiletime error, to avoid this
confusion.
ADJUST
ADJUST {
...
}
Since version 0.43.
Declares an adjust block for this component class. This block of code runs within the constructor, after
any "BUILD" blocks and automatic field value assignment. It can make any final adjustments to the
instance (such as initialising fields from calculated values). No additional parameters are passed.
An adjust block is not a subroutine and thus is not permitted to use subroutine attributes. Note that an
"ADJUST" block is a named phaser block and not a method; it does not use the "sub" or "method" keyword.
ADJUSTPARAMS
ADJUSTPARAMS ( $params ) { # on perl 5.26 onwards
...
}
ADJUSTPARAMS {
my $params = shift;
...
}
Since version 0.51.
Declares an adjust block for this component class that receives the parameters hash reference. This block
of code runs within the constructor at the same time as "ADJUST" blocks, but receives in addition a
reference to the hash containing the current constructor parameters. This hash will not contain any
constructor parameters already consumed by ":param" declarations on any fields, but only the leftovers
once those are processed.
The code in the block should "delete" from this hash any parameters it wishes to consume. Once all the
"ADJUSTPARAMS" blocks have run, any remaining keys in the hash will be considered errors, subject to the
":strict(params)" check.
requires
requires NAME;
Declares that this role requires a method of the given name from any class that implements it. It is an
error at compiletime if the implementing class does not provide such a method.
This form of declaring a required method is now vaguely discouraged, in favour of the bodyless "method"
form described above.
CREPT FEATURES
While not strictly part of being an object system, this module has nevertheless gained a number of
behaviours by feature creep, as they have been found useful.
Implied Pragmata
In order to encourage users to write clean, modern code, the body of the "class" block acts as if the
following pragmata are in effect:
use strict;
use warnings;
no indirect ':fatal'; # or no feature 'indirect' on perl 5.32 onwards
use feature 'signatures';
This list may be extended in subsequent versions to add further restrictions and should not be considered
exhaustive.
Further additions will only be ones that remove "discouraged" or deprecated language features with the
overall goal of enforcing a more clean modern style within the body. As long as you write code that is in
a clean, modern style (and I fully accept that this wording is vague and subjective) you should not find
any new restrictions to be majorly problematic. Either the code will continue to run unaffected, or you
may have to make some small alterations to bring it into a conforming style.
Yield True
A "class" statement or block will yield a true boolean value. This means that it can be used directly
inside a .pm file, avoiding the need to explicitly yield a true value from the end of it.
SUBCLASSING CLASSIC PERL CLASSES
There are a number of details specific to the case of deriving an "Object::Pad" class from an existing
classic Perl class that is not implemented using "Object::Pad".
Storage of Instance Data
Instances will pick either the ":repr(HASH)" or ":repr(magic)" storage type.
Object State During Methods Invoked By Superclass Constructor
It is common in classic Perl OO style to invoke methods on $self during the constructor. This is
supported here since "Object::Pad" version 0.19. Note however that any methods invoked by the superclass
constructor may not see the object in a fully consistent state. (This fact is not specific to using
"Object::Pad" and would happen in classic Perl OO as well). The field initialisers will have been invoked
but the "BUILD" blocks will not.
For example; in the following
package ClassicPerlBaseClass {
sub new {
my $self = bless {}, shift;
say "Value seen by superconstructor is ", $self->get_value;
return $self;
}
sub get_value { return "A" }
}
class DerivedClass :isa(ClassicPerlBaseClass) {
has $_value = "B";
BUILD {
$_value = "C";
}
method get_value { return $_value }
}
my $obj = DerivedClass->new;
say "Value seen by user is ", $obj->get_value;
Until the "ClassicPerlBaseClass::new" superconstructor has returned the "BUILD" block will not have been
invoked. The $_value field will still exist, but its value will be "B" during the superconstructor. After
the superconstructor, the "BUILD" blocks are invoked before the completed object is returned to the user.
The result will therefore be:
Value seen by superconstructor is B
Value seen by user is C
STYLE SUGGESTIONS
While in no way required, the following suggestions of code style should be noted in order to establish a
set of best practices, and encourage consistency of code which uses this module.
$VERSION declaration
While it would be nice for CPAN and other toolchain modules to parse the embedded version declarations in
"class" statements, the current state at time of writing (June 2020) is that none of them actually do. As
such, it will still be necessary to make a once-per-file $VERSION declaration in syntax those modules can
parse.
Further note that these modules will also not parse the "class" declaration, so you will have to
duplicate this with a "package" declaration as well as a "class" keyword. This does involve repeating the
package name, so is slightly undesirable.
It is hoped that eventually upstream toolchain modules will be adapted to accept the "class" syntax as
being sufficient to declare a package and set its version.
See also
• <https://github.com/Perl-Toolchain-Gang/Module-Metadata/issues/33>
File Layout
Begin the file with a "use Object::Pad" line; ideally including a minimum-required version. This should
be followed by the toplevel "package" and "class" declarations for the file. As it is at toplevel there
is no need to use the block notation; it can be a unit class.
There is no need to "use strict" or apply other usual pragmata; these will be implied by the "class"
keyword.
use Object::Pad 0.16;
package My::Classname 1.23;
class My::Classname;
# other use statements
# has, methods, etc.. can go here
Field Names
Field names should follow similar rules to regular lexical variables in code - lowercase, name components
separated by underscores. For tiny examples such as "dumb record" structures this may be sufficient.
class Tag {
has $name :mutator;
has $value :mutator;
}
In larger examples with lots of non-trivial method bodies, it can get confusing to remember where the
field variables come from (because we no longer have the "$self->{ ... }" visual clue). In these cases it
is suggested to prefix the field names with a leading underscore, to make them more visually distinct.
class Spudger {
has $_grapefruit;
...
method mangle {
$_grapefruit->peel; # The leading underscore reminds us this is a field
}
}
WITH OTHER MODULES
Syntax::Keyword::Dynamically
A cross-module integration test asserts that "dynamically" works correctly on object instance fields:
use Object::Pad;
use Syntax::Keyword::Dynamically;
class Container {
has $value = 1;
method example {
dynamically $value = 2;
,..
# value is restored to 1 on return from this method
}
}
Future::AsyncAwait
As of Future::AsyncAwait version 0.38 and Object::Pad version 0.15, both modules now use
XS::Parse::Sublike to parse blocks of code. Because of this the two modules can operate together and
allow class methods to be written as async subs which await expressions:
use Future::AsyncAwait;
use Object::Pad;
class Example
{
async method perform ($block)
{
say "$self is performing code";
await $block->();
say "code finished";
}
}
These three modules combine; there is additionally a cross-module test to ensure that object instance
fields can be "dynamically" set during a suspended "async method".
DESIGN TODOs
The following points are details about the design of pad field-based object systems in general:
• Is multiple inheritence actually required, if role composition is implemented including giving roles
the ability to use private fields?
• Consider the visibility of superclass fields to subclasses. Do subclasses even need to be able to see
their superclass's fields, or are accessor methods always appropriate?
Concrete example: The "$self->{split_at}" access that Tickit::Widget::HSplit makes of its parent
class Tickit::Widget::LinearSplit.
IMPLEMENTATION TODOs
These points are more about this particular module's implementation:
• Consider multiple inheritence of subclassing, if that is still considered useful after adding roles.
• Work out why "no indirect" doesn't appear to work properly before perl 5.20.
• Work out why we don't get a "Subroutine new redefined at ..." warning if we
sub new { ... }
• The "local" modifier does not work on field variables, because they appear to be regular lexicals to
the parser at that point. A workaround is to use Syntax::Keyword::Dynamically instead:
use Syntax::Keyword::Dynamically;
has $loglevel;
method quietly {
dynamically $loglevel = LOG_ERROR;
...
}
FEEDBACK
The following resources are useful forms of providing feedback, especially in the form of reports of what
you find good or bad about the module, requests for new features, questions on best practice, etc...
• The RT queue at <https://rt.cpan.org/Dist/Display.html?Name=Object-Pad>.
• The "#cor" IRC channel on "irc.perl.org".
SPONSORS
With thanks to the following sponsors, who have helped me be able to spend time working on this module
and other perl features.
• Oetiker+Partner AG <https://www.oetiker.ch/en/>
• Deriv <http://deriv.com>
• Perl-Verein Schweiz <https://www.perl-workshop.ch/>
Additional details may be found at <https://github.com/Ovid/Cor/wiki/Sponsors>.
AUTHOR
Paul Evans <leonerd@leonerd.org.uk>
perl v5.34.0 2022-02-18 Object::Pad(3pm)