Re: "temp" vs "my"
[email protected] (Brad Gilbert) Wed, 3 Oct 2018 19:19:04 -0500
| Newsgroups | perl.perl6.language |
|---|---|
| Message-ID | <CAD2L-T3H+-Ct8aLn7CX4v0KPNtCaZr4BCSmB6Dr5cQ0X=DhEpg@mail.gmail.com> |
Note that OUTER::<$v> only goes up one level.
So to go up two levels OUTER::OUTER::<$v>
There is also OUTERS::<$v> which will go up as many levels as it needs
to find the variable
{
my $a =3D 1;
my $b =3D 2;
{
my $a =3D 3;
{
say OUTER::<$a>; # 3
say OUTER::OUTER::<$a>; # 1
say OUTERS::<$a>; # 3 # only one level
say OUTERS::<$b>; # 2 # two levels
}
}
}
On Wed, Oct 3, 2018 at 10:31 AM yary <[email protected]> wrote:
>
> Thanks! Knew I'd seen the concept of OUTER but couldn't remember the keyw=
ord.
>
> -y
>
> On Wed, Oct 3, 2018 at 5:51 AM, Timo Paulssen <[email protected]> wrote:
>>
>> you can refer to the outer $v as OUTER::('$v'), that ought to help :)
>>
>> On 03/10/2018 08:10, yary wrote:
>>
>> Reading and playing with https://docs.perl6.org/routine/temp
>>
>> There's an example showing how temp is "dynamic" - that any jump outside=
a block restores the value. All well and good.
>>
>> Then I thought, what if I want a lexical temporary value- then use "my"-=
and this is all well and good:
>>
>> my $v =3D "original";
>> {
>> my $v =3D "new one";
>> start {
>> say "[PROMISE] Value before block is left: `$v`";
>> sleep 1;
>> say "[PROMISE] Block was left while we slept; value is still `$v=
`";
>> }
>> sleep =C2=BD;
>> say "About to leave the block; value is `$v`";
>> }
>> say "Left the block; value is now `$v`";
>> sleep 2;
>>
>> Then I thought, well, what if I want to initialize the inner $v with the=
outer $v.
>>
>> my $v =3D "original";
>> {
>> my $v =3D $v; # "SORRY! Cannot use variable $v in declaration to ini=
tialize itself"
>> say "inner value is $v";
>> $v=3D "new one";
>> ...
>>
>> Gentle reader, how would you succinctly solve this contrived example? An=
ything you like better than this?
>>
>> my $v =3D "original";
>> given $v -> $v is copy {
>> say "inner value is $v"; # "original", good
>> $v=3D "new one";
>> ....
>>
>> -y
>
>