The initial implementation of feature bits for faster access to
feature flags used a single U32 member in COP to store the bits, but
we're now up to 24 features, so rather than leaving this to the last
minute I've re-worked regen/feature.pl to allow multiple U32 fields.
As these only permit `any BLOCK LIST` and not the deferred-expression
form like `grep EXPR, LIST`, we create a whole new token type, BLKLSTOP,
to represent these. The parser then only accepts the block form and not
the expression form when parsing these.
I originally optimised populating cop_features for eval by storing
the hints mask in "feature/bits" and then fetching that when
re-populating the hints for eval.
But that has turned out to be too fragile, so iterate over the
possible feature keys and populate cop_features from that.
I could perhaps have avoided this cost by ensuring "feature/bits" was
set where else it was needed, but this code already iterates to build
the hints hash, iterating again doesn't increase the scale of the work
we're doing.
This updates the mode-line for most of our generated files so that
they include file type information so they will be properly syntax
highlighted on github.
This does not make any other functional changes to the files.
[Note: Commit message rewritten by Yves]
Adds a new experimental warning, feature, keywords and enough parsing to
implement basic classes with an empty `new` constructor method.
Inject a $self lexical into method bodies; populate it with the object instance, suitably shifted
Creates a new OP_METHSTART opcode to perform method setup
Define an aux flag to remark which stashes are classes
Basic implementation of fields.
Basic anonymous methods.
Per RFC 18, whenever `use feature 'module_true';` is enabled in a scope,
any file required with `require` has an implicit return value of true
and will not trigger the "did not return a true value" error condition.
This includes logic to use the OPf_SPECIAL flag for OP_RETURN listops to
indicate that the module_true feature is in effect when it executes.
This flag plays no role unless the OP_RETURN tail calls the pp_leaveeval
logic, so it doesn't affect normal sub returns.
PL_hints expands to PL_compiling.cop_hints. So there is no
point in doing
PL_curcop == &PL_compiling ? PL_hints : PL_curcop->cop_hints
as it resolves to doing:
PL_curcop->cop_hints
but with a comparison, which likely kills any speed advantage
the direct access might provide.
The old define is left around to validate that the two are the same
if needed.
Adds syntax `defer { BLOCK }` to create a deferred block; code that is
deferred until the scope exits. This syntax is guarded by
use feature 'defer';
Adds a new opcode, `OP_PUSHDEFER`, which is a LOGOP whose `op_other` field
gives the start of an optree to be deferred until scope exit. That op
pointer will be stored on the save stack and invoked as part of scope
unwind.
Included is support for `B::Deparse` to deparse the optree back into
syntax.
Adds a new infix operator named `isa`, with the semantics that
$x isa SomeClass
is true if and only if `$x` is a blessed object reference that is either
`SomeClass` directly, or includes the class somewhere in its @ISA
hierarchy. It is false without warning or error for non-references or
non-blessed references.
This operator respects `->isa` method overloading, and is intended to
replace boilerplate code such as
use Scalar::Util 'blessed';
blessed($x) and $x->isa("SomeClass")
Perform only a bit check instead of a much more expensive hash
lookup to test features.
For now I've just added a U32 to the cop structure to store the bits,
if we need more we could either add more bits directly, or make it a
pointer.
We don't have the immediate need for a pointer that warning do since
we don't dynamically add new features during compilation/runtime.
The changes to %^H are retained so that caller() can be used from perl
code to check the features enabled at a given caller's scope.
As proposed by RJBS.
The "5.24" feature bundle (and therefore C<< use v5.24 >>) now enable
postderef and postderef_qq.
I can't find any precedent for what to do with the relevant experimental::*
warnings category when an experimental feature graduates to acceptance. I
have elected to leave the category in place, so that code doing C<< no
warnings "experimental::postderef" >> will continue to work. This means that
C<< use warnings "experimental::postderef" >> is also accepted, but has no
effect.
Declarative syntax to unwrap argument list into lexical variables.
"sub foo ($a,$b) {...}" checks number of arguments and puts the
arguments into lexical variables. Signatures are not equivalent to the
existing idiom of "sub foo { my($a,$b) = @_; ... }". Signatures are only
available by enabling a non-default feature, and generate warnings about
being experimental. The syntactic clash with prototypes is managed by
disabling the short prototype syntax when signatures are enabled.
Otherwise CURRENT_FEATURE_BUNDLE will end up including any hints added
later that happen to use higher bits.
This was causing autobox to turn off all features, causing failures
for Dist::Zilla::PluginBundle::AVAR.
I’m not adding tests for this, as such tests would need constant
tweaking in future perl developement. What autobox is doing is
naughty and unsupported anyway.
