On Tue Jan 25 09:08:20 2011, masak wrote:
> <masak> there is at least a little code smell inherent in p6 dynamic
> variables, since these are not namespaced at all. it'd be nice to see
> a solution for namespacing dynamic variables.
> <TimToady> dynamic var is a lexical, not a global
> <TimToady> masak: I don't think dynamic variables are useful enough to
> warrant the baggage of namespacing
> <TimToady> dynamic hashes and common prefixes are probably good enough
> <masak> TimToady: maybe.
> <masak> TimToady: but I'd be wary every time I used both dynamicals
> and callbacks.
> <TimToady> esp if we allow :: in a dynamic name :)
> <masak> :D
> <masak> then I'm fine :)
> <TimToady> we can think about that
> <TimToady> might also be useful to target the final default to a
> package other than GLOBAL
> <TimToady> which makes it slightly less smelly, I suspect
> <TimToady> std: my $*FOO::BAR = 2;
> <p6eval> std 625303c: OUTPUT«ok 00:01 121m»
> <TimToady> heh
> <masak> rakudo: my $*FOO::BAR = 42; say $*FOO::BAR
> <p6eval> rakudo 723986: OUTPUT«Cannot modify readonly value in
> '&infix:<=>' at line 1 in main program body at line
> 22:/tmp/2PoIAPndlk»
> * masak submits rakudobug
> <TimToady> not clear that STD parsed it correctly though
> <masak> should it error out on FOO:: not being predeclared?
> <TimToady> there's definitely something wonky in the STD parse of that
> <TimToady> nevertheless it can probably be made to work someday
> <masak> TimToady: well, Rakudo parsed it too, since it got to runtime.
> <TimToady> package globals don't generally care about whether FOO::
> exists yet for normal variables
> <masak> ok.
> <TimToady> std: $FOO::bar = 42;
> <p6eval> std 625303c: OUTPUT«ok 00:01 120m»
> <masak> rakudo: module Foo {}; my $*Foo::bar = 42; say $*Foo::bar [18:06]
> <p6eval> rakudo 723986: OUTPUT«Cannot modify readonly value [...]
More recent feeling is that we don't want this feature:
http://irclog.perlgeek.de/perl6/2015-10-15#i_11381191
So I've made the compiler reject such things with an error:
$ perl6-m -e "my $*FOO::BAR"
===SORRY!=== Error while compiling -e
Dynamic variables cannot have package-like names, like $*FOO::BAR
at -e:1
------> my $*FOO::BAR<HERE><EOL>
Tests are in S02-names-vars/contextual.t. In the event we do decide we want
this syntax for something in the future, rejecting it outright now while we're
not sure nicely reserves it for then.
/jnthn
