#1138: Create a 'vivify' opcode
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Reporter: Austin_Hastings | Type: todo
Status: new | Priority: normal
Milestone: | Component: core
Version: 1.7.0 | Severity: medium
Keywords: | Lang:
Patch: | Platform:
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Comment(by pmichaud):
Several related points.
First, also take a look at TT #787, which deals with the issue of lvalues
in Parrot in general, and is very related to the above code pattern that
NQP/PCT generate.
Second, please-please-please note that we're generally deprecating the use
of string constants as class/PMC identifiers -- PCT's use of strings there
is really a fossil. If we introduce a vivify opcode, it needs to be {{{
vivify P, PC }}}.
Third, based on an improved understanding of the Perl 6 specification, NQP
and Rakudo will be able to eliminate the above pattern altogether for
lexical variables -- i.e., we can guarantee that lexicals will be
initialized to Undef at declaration time, and thus all lexical lookups
will be able to avoid the "vivify if null" sequence altogether. We'll
still need the vivify sequence for aggregate lookups (hashes/arrays), but
there we should also deal with the issue of lvalue vivification and value
assignment.
Hope this can spark some useful discussion.
Pm
--
Ticket URL: <https://trac.parrot.org/parrot/ticket/1138#comment:1>
Parrot <https://trac.parrot.org/parrot/>
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