Correct enum incantation?
Hello,
I've been reading over an interesting Answer on StackOverflow by wamba:
https://stackoverflow.com/a/67324175/7270649
I started trying to explore enums on my own and quickly realized that
method calls on enums are different from simple key/value pairs. For enums,
calling a `.key` or `.value` or `.kv` method won't work. Instead one must
use something like `.^enum_values` or `.^enum_value_list`.
Can someone explain how `.^enum_values` or `.^enum_value_list` came to be
the **correct** incantation for enums, and why there is no equivalent
`.^enum_keys` or `.^enum_key_list` commands? Thank you, Bill.
> # In the Raku REPL (wamba's enum example 'Month')
> enum Month (jan => 1, |);
Map.new((apr => 4, aug => 8, dec => 12, feb => 2, jan => 1, jul => 7, jun
=> 6, mar => 3, may => 5, nov => 11, oct => 10, sep => 9))
>
> Month.^enum_values
{apr => 4, aug => 8, dec => 12, feb => 2, jan => 1, jul => 7, jun => 6, mar
=> 3, may => 5, nov => 11, oct => 10, sep => 9}
> Month.^enum_value_list
(jan feb mar apr may jun jul aug sep oct nov dec)
>
> Month.^enum_keys
No such method 'enum_keys' for invocant of type
'Perl6::Metamodel::EnumHOW'
in block at line 4
> Month.^enum_key_list
No such method 'enum_key_list' for invocant of type
'Perl6::Metamodel::EnumHOW'
in block at line 1
>
> #Random keyword attempts:
> Month.key
Invocant of method 'key' must be an object instance of type 'Mu', not a
type object of type 'Month'. Did you forget a '.new'?
in block at line 1
> Month>>.key
Invocant of method 'key' must be an object instance of type 'Mu', not a
type object of type 'Month'. Did you forget a '.new'?
in block at line 1
> Month.keys
()
> Month>>.keys
(())
Re: Correct enum incantation?
Thank you Fernando! (still on Rakudo 2020.10 here). On Wed, May 5, 2021 at 10:24 AM Fernando Santagata < nando.santag...@gmail.com> wrote: > On Wed, May 5, 2021 at 6:00 PM William Michels via perl6-users < > perl6-us...@perl.org> wrote: > >> Hello, >> >> I've been reading over an interesting Answer on StackOverflow by wamba: >> >> https://stackoverflow.com/a/67324175/7270649 >> >> I started trying to explore enums on my own and quickly realized that >> method calls on enums are different from simple key/value pairs. For enums, >> calling a `.key` or `.value` or `.kv` method won't work. Instead one must >> use something like `.^enum_values` or `.^enum_value_list`. >> > > Probably you need the new and shiny compiler ;) > > > $*RAKU.compiler.version > v2021.04 > > Month.keys > (oct dec aug jun mar apr feb nov jul may sep jan) > > Month.values > (11 6 9 2 5 7 3 12 8 4 10 1) > > .say for Month.kv > nov > 11 > jul > 7 > sep > 9 > jan > 1 > oct > 10 > mar > 3 > jun > 6 > apr > 4 > aug > 8 > dec > 12 > feb > 2 > may > 5 > -- > Fernando Santagata >
Re: Correct enum incantation?
On Wed, May 5, 2021 at 6:00 PM William Michels via perl6-users < perl6-us...@perl.org> wrote: > Hello, > > I've been reading over an interesting Answer on StackOverflow by wamba: > > https://stackoverflow.com/a/67324175/7270649 > > I started trying to explore enums on my own and quickly realized that > method calls on enums are different from simple key/value pairs. For enums, > calling a `.key` or `.value` or `.kv` method won't work. Instead one must > use something like `.^enum_values` or `.^enum_value_list`. > Probably you need the new and shiny compiler ;) > $*RAKU.compiler.version v2021.04 > Month.keys (oct dec aug jun mar apr feb nov jul may sep jan) > Month.values (11 6 9 2 5 7 3 12 8 4 10 1) > .say for Month.kv nov 11 jul 7 sep 9 jan 1 oct 10 mar 3 jun 6 apr 4 aug 8 dec 12 feb 2 may 5 -- Fernando Santagata
