Re: Not a bug?
On Mon, Jan 12, 2009 at 3:54 PM, Larry Wall wrote:
> On Mon, Jan 12, 2009 at 01:19:12PM -0800, Jon Lang wrote:
> : As well, isn't there a way to escape a character that would otherwise
> : be interpolated? If the intent were as you suppose, the original
> : could be rewritten as:
> :
> : $ perl6 -e 'my $foo = "foo";say "\{" ~ $foo ~ "}"'
>
> Sure, though in any case I'd probably prefer:
>
>$ perl6 -e 'my $foo = "foo"; say Qs/{$foo}/'
>
> : (Or would you need to escape the closing curly brace as well as the
> : opening one?)
>
> Not unless something outside of it all was attempting to count braces.
> But the P6 parser has sworn off all such activities for P6-derived
> code. Parsing something first as a string and then again as some
> other language is generally looked upon as a Bad Plan these days.
>
> Which is, of course, why "{" is a problem now. Perhaps use of nested
> double quotes deserves a warning.
>
masak++ was right, if you use single quotes it works properly. Here's how
you do it from a bash prompt:
$ ./perl6 -e 'my $foo = '\''foo'\''; say '\''{'\'' ~ $foo ~ '\''}'\'' '
{foo}
Notice the overly redundant single-quotes; in fact, all of those quotes are
single quotes.
-Jason "s1n" Switzer
Re: Not a bug?
On Mon, Jan 12, 2009 at 01:19:12PM -0800, Jon Lang wrote:
: As well, isn't there a way to escape a character that would otherwise
: be interpolated? If the intent were as you suppose, the original
: could be rewritten as:
:
: $ perl6 -e 'my $foo = "foo";say "\{" ~ $foo ~ "}"'
Sure, though in any case I'd probably prefer:
$ perl6 -e 'my $foo = "foo"; say Qs/{$foo}/'
: (Or would you need to escape the closing curly brace as well as the
: opening one?)
Not unless something outside of it all was attempting to count braces.
But the P6 parser has sworn off all such activities for P6-derived
code. Parsing something first as a string and then again as some
other language is generally looked upon as a Bad Plan these days.
Which is, of course, why "{" is a problem now. Perhaps use of nested
double quotes deserves a warning.
Larry
Re: Not a bug?
On Mon, Jan 12, 2009 at 1:08 PM, Larry Wall wrote:
> On Mon, Jan 12, 2009 at 03:43:47AM -0800, Jon Lang wrote:
> : On Mon, Jan 12, 2009 at 2:15 AM, Carl Mäsak wrote:
> : > Ovid (>):
> : >> $ perl6 -e 'my $foo = "foo";say "{" ~ $foo ~ "}"'
> : >> ~ foo ~
> : >
> : > Easy solution: only use double quotes when you want to interpolate. :)
> : >
> : > This is not really an option when running 'perl6 -e' under bash, though.
> :
> : $ perl6 -e 'my $foo = "foo";say q:qq({" ~ $foo ~ "})'
> :
> : ...or something to that effect.
>
> Assuming that's what was wanted. I figgered they want something more
> like:
>
>$ perl6 -e 'my $foo = "foo"; say q[{] ~ $foo ~ q[}];'
True enough. Either one of these would be more clear than the
original example in terms of user intent.
As well, isn't there a way to escape a character that would otherwise
be interpolated? If the intent were as you suppose, the original
could be rewritten as:
$ perl6 -e 'my $foo = "foo";say "\{" ~ $foo ~ "}"'
(Or would you need to escape the closing curly brace as well as the
opening one?)
--
Jonathan "Dataweaver" Lang
Re: Not a bug?
On Mon, Jan 12, 2009 at 03:43:47AM -0800, Jon Lang wrote:
: On Mon, Jan 12, 2009 at 2:15 AM, Carl Mäsak wrote:
: > Ovid (>):
: >> $ perl6 -e 'my $foo = "foo";say "{" ~ $foo ~ "}"'
: >> ~ foo ~
: >
: > Easy solution: only use double quotes when you want to interpolate. :)
: >
: > This is not really an option when running 'perl6 -e' under bash, though.
:
: $ perl6 -e 'my $foo = "foo";say q:qq({" ~ $foo ~ "})'
:
: ...or something to that effect.
Assuming that's what was wanted. I figgered they want something more
like:
$ perl6 -e 'my $foo = "foo"; say q[{] ~ $foo ~ q[}];'
Larry
Re: Not a bug?
HaloO,
Tim Bunce wrote:
On Sun, Jan 11, 2009 at 04:41:12PM -0800, Ovid wrote:
I really don't think this is a bug, but it did confuse the heck out of me at
first. This *is* expected behavior due to how {} is interpolated in strings,
yes?
$ perl6 -e 'my $foo = "foo";say "<" ~ $foo ~ ">"'
$ perl6 -e 'my $foo = "foo";say "{" ~ $foo ~ "}"'
~ foo ~
I presume string interpolation is, er, "set-up", at compile-time.
So it only happened here because "{" ~ $foo ~ "}" was rewritten to
"{$foo}" at compile-time. And if "{" and "}" were replaced with
variables, for example, then the interpolation wouldn't have happened.
Right?
The point is that the code that is interpolated is just the
string " ~ $foo ~ " which is interpolated when the closure runs.
That is there are two nested interpolations! Note that you can't
use "{" to initialize a variable because it either ends in a syntax
error or as in the given example swallows some code into a string.
This works as you intent:
my $left = '{';
my $right = '}';
my $foo = "foo"; # no danger with interpolation
say $left ~ $foo ~ $right;
That is in the example from Ovid there are *no* concatenations!
Regards, TSa.
--
"The unavoidable price of reliability is simplicity" -- C.A.R. Hoare
"Simplicity does not precede complexity, but follows it." -- A.J. Perlis
1 + 2 + 3 + 4 + ... = -1/12 -- Srinivasa Ramanujan
Re: Not a bug?
On Sun, Jan 11, 2009 at 04:41:12PM -0800, Ovid wrote:
> I really don't think this is a bug, but it did confuse the heck out of me at
> first. This *is* expected behavior due to how {} is interpolated in strings,
> yes?
>
> $ perl6 -e 'my $foo = "foo";say "<" ~ $foo ~ ">"'
>
> $ perl6 -e 'my $foo = "foo";say "{" ~ $foo ~ "}"'
>~ foo ~
I presume string interpolation is, er, "set-up", at compile-time.
So it only happened here because "{" ~ $foo ~ "}" was rewritten to
"{$foo}" at compile-time. And if "{" and "}" were replaced with
variables, for example, then the interpolation wouldn't have happened.
Right?
Tim.
Re: Not a bug?
On Mon, Jan 12, 2009 at 2:15 AM, Carl Mäsak wrote:
> Ovid (>):
>> $ perl6 -e 'my $foo = "foo";say "{" ~ $foo ~ "}"'
>> ~ foo ~
>
> Easy solution: only use double quotes when you want to interpolate. :)
>
> This is not really an option when running 'perl6 -e' under bash, though.
$ perl6 -e 'my $foo = "foo";say q:qq({" ~ $foo ~ "})'
...or something to that effect.
--
Jonathan "Dataweaver" Lang
Re: Not a bug?
Ovid (>):
> $ perl6 -e 'my $foo = "foo";say "{" ~ $foo ~ "}"'
> ~ foo ~
Easy solution: only use double quotes when you want to interpolate. :)
This is not really an option when running 'perl6 -e' under bash, though.
// Carl
Re: Not a bug?
On Sun, Jan 11, 2009 at 04:41:12PM -0800, Ovid wrote:
: I really don't think this is a bug, but it did confuse the heck out of me at
first. This *is* expected behavior due to how {} is interpolated in strings,
yes?
:
: $ perl6 -e 'my $foo = "foo";say "<" ~ $foo ~ ">"'
:
: $ perl6 -e 'my $foo = "foo";say "{" ~ $foo ~ "}"'
:~ foo ~
Yep, that's working right. Or at least, working as designed... :)
Larry
Not a bug?
I really don't think this is a bug, but it did confuse the heck out of me at
first. This *is* expected behavior due to how {} is interpolated in strings,
yes?
$ perl6 -e 'my $foo = "foo";say "<" ~ $foo ~ ">"'
$ perl6 -e 'my $foo = "foo";say "{" ~ $foo ~ "}"'
~ foo ~
Cheers,
Ovid
--
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