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Re: Pre-RFC Deep constants

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Branislav Zahradník
March 9, 2023 19:43
Re: Pre-RFC Deep constants
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Few short assorted thoughts:

- write once behaviour will be great
   - referring to my earlier proposal for `not-exists` value - define
behaviour: constant not-existing value can be assigned once

- perl core imho needs to rework magic (I'd vote for function tables per SV
- where function table will be on par with packages / class literals)

- should there be an mechanism to turn it on/off in runtime?, eg
  my $var = { ... };
  foo ($var : const);
  $var->{bar} //= default value;
  return $bar;

- how it should behave when returning copy? clone / copy-on-write? eg:
  state $var :const = { ... };
  return $var : copy-on-write;

- can it be localized? If localized, should it still be "deep constant" ?

- how initialization with read-write data will behave?, eg:
  my $foo = { ... };
  my $bar : const = { foo => $foo };

- it will be also nice to be able to bound read-write to visibility of
symbol(s) (aka protected)
  - class may mark its instance as conditional read only
  - user may mark instance as fully read-only


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