Re: Quickcheck of context of index expressions
On Tue, Apr 26, 2005 at 03:33:44AM +0800, Autrijus Tang wrote: : Another quick check on expression context for indexed expressions. : Please sanity-check the return value of want() below: : : @x[0] = want(); # scalar context Good. : @x[want()] = $_; # scalar context : @x[want()] = @_; # scalar context Maybe unknown context, which defaults to list. : @x[0,] = want(); # list context : @x[want(),] = $_; # list context : @x[want(),] = @_; # list context : $_ = @x[want()]; # scalar context : @_ = @x[want()]; # list context No, I think they're all list context. Larry
Re: Quickcheck of context of index expressions
On Tue, Apr 26, 2005 at 03:56:37AM +0800, Autrijus Tang wrote:
: On Tue, Apr 26, 2005 at 03:33:44AM +0800, Autrijus Tang wrote:
: Another quick check on expression context for indexed expressions.
: Please sanity-check the return value of want() below:
:
: @x[0] = want(); # scalar context
: @x[want()] = $_;# scalar context
: @x[want()] = @_;# scalar context
: @x[0,] = want();# list context
: @x[want(),] = $_; # list context
: @x[want(),] = @_; # list context
: $_ = @x[want()];# scalar context
: @_ = @x[want()];# list context
:
: Oh, and under the S02 rules above (the index expression inherits
: outer context on RHS), Pugs currently does this:
:
: $_ = %x{ 1, 2 }
: --- reduces to ---
: $_ = %x{ [1, 2] }
: --- reduces to ---
: $_ = %x{ 1 2 }
:
: Which is, well, very surprising. Where did I get wrong?
I think S02 is probably wrong. It should be unknown/list context.
Sorry for the short answers, but I'm in Russia behind a flakey network
connection, which is probably going away entirely at any moment (the
network connection, not Russia.) I can clarify more next week when
I get back.
Larry
Re: Quickcheck of context of index expressions
On Fri, Apr 29, 2005 at 06:22:57AM -0700, Larry Wall wrote: : @x[want()] = $_; # scalar context : @x[want()] = @_; # scalar context Maybe unknown context, which defaults to list. I think allowing unknown LHS index expression to default to scalar context is a bit more useful here. Since we have: @x[0] = @y;# scalar @x[0,] = @y;# list This may be more intuitive: @x[idx()] = @y;# scalar @x[idx(),] = @y;# list Than this: @x[+idx()] = @y;# scalar @x[idx()] = @y;# list But I don't really feel strongly one way or another, as long as it is specced down. :) Thanks, /Autrijus/ pgpQVFZNKCIEY.pgp Description: PGP signature
Re: Quickcheck of context of index expressions
On Fri, Apr 29, 2005 at 06:22:57AM -0700, Larry Wall wrote: : @x[want()] = $_; # scalar context : @x[want()] = @_; # scalar context Maybe unknown context, which defaults to list. : @x[0,] = want(); # list context : @x[want(),] = $_; # list context : @x[want(),] = @_; # list context : $_ = @x[want()]; # scalar context : @_ = @x[want()]; # list context No, I think they're all list context. Okay. r2478 has them reverted to the original form, which inspects the declared return type of want() to see if it is a subtype of Scalar; if it is, then it is taken as scalar context; otherwise (or if multiple multisubs are possible), it defaults to list context. Thanks, /Autrijus/ pgp0HZ5CR3H7H.pgp Description: PGP signature
Re: Quickcheck of context of index expressions
On Tue, Apr 26, 2005 at 03:33:44AM +0800, Autrijus Tang wrote:
Another quick check on expression context for indexed expressions.
Please sanity-check the return value of want() below:
@x[0] = want(); # scalar context
@x[want()] = $_; # scalar context
@x[want()] = @_; # scalar context
@x[0,] = want(); # list context
@x[want(),] = $_; # list context
@x[want(),] = @_; # list context
$_ = @x[want()]; # scalar context
@_ = @x[want()]; # list context
Oh, and under the S02 rules above (the index expression inherits
outer context on RHS), Pugs currently does this:
$_ = %x{ 1, 2 }
--- reduces to ---
$_ = %x{ [1, 2] }
--- reduces to ---
$_ = %x{ 1 2 }
Which is, well, very surprising. Where did I get wrong?
Thanks,
/Autrijus/
pgpWPjfDiyNHu.pgp
Description: PGP signature
