Re^2: map syntax error -- weird

[hdb]

in reply to Re: map syntax error -- weird
in thread map syntax error -- weird

Why does this work? (same result as your proposals)

my %opt;
my @vals = qw(title artist album);
my @opts = map { "$_"."=s" => \$opt{$_} } @vals;
print @opts;

UPDATE: Guess: Because there is some statement in there that needs to be executed rather than a static string only?

[BrowserUk]

Guess: Because there is some statement in there that needs to be executed rather than a static string only?

Indeed.

[LanX]

> Why does this work? (same result as your proposals)

There is no clear rule to distinguish between code-block and hash-ref!!!

The parser uses DWIM heuristics to guess if it looks more like a hash-ref or not. (Furthermore "w/o look-ahead")

So in complicated cases you need to give hints for what you mean.

This ambiguity should be one reason why Perl6 switched from {} to <> to indicate hashes.

> UPDATE: Guess: Because there is some statement in there that needs to be executed rather than a static string only?

well it's a perfect hash-ref!

  DB<112> $hr={ "$_"."=s" => \$opt{$_} }
 => { "=s" => \undef }

But I think the used heuristic must be quite simple, something like

  (bareword || variable) (comma || fatcomma) (expr)

So "$_"."=s" is already to complex to fit this rule of thumb.