Re: %MY (was What's MY.line?)
On Thu, Jul 11, 2002 at 04:43:34PM -0400, Melvin Smith wrote:
And side effects like I call you, you modify me invisibly seems
more like taking dangerous drugs than programming.
Yep, I warned you about calling that routine, now look what it did to
your brains.
Um, I shouldn't really mention Devel::LexAlias then, since with it you
can already write
caller(1).MY{'$y'} := caller(1).MY{'$x'};
as
lexalias(1, $y, upto(1, $x));
Where upto is would be a simple wrapper around my
Devel::Caller::caller_cv and Robin Houston's PadWalker::peek_sub
No, I'm not waiting till perl6 for the drugs to kick in...
--
Richard Clamp [EMAIL PROTECTED]
Re: What's MY.line?
Chip Salzenberg writes: Ouch. I gather, then, that nntp.perl.org does not house complete list archives, or else the discussion was not on p6-language ... ? It should have complete archives. It uses the same backend data as the html version on archive.develooper.com.
Re: What's MY.line?
At 5:46 AM +0100 7/11/02, [EMAIL PROTECTED] wrote: Dan Sugalski [EMAIL PROTECTED] writes: At 4:24 PM +0100 7/10/02, [EMAIL PROTECTED] wrote: Dan Sugalski [EMAIL PROTECTED] writes: At 9:50 PM -0400 7/9/02, Chip Salzenberg wrote: 3. Is C%MY intended to reflect the PAD? Yes. Hey! How's this for a scary thought: $continuation.the_pad What's that supposed to do, though? You want to alter the pad that gets put in place at the top of the pad list for a continuation? No problem. A bad idea, mind, but no problem... :) I was thinking it would get the pad of the block from which the continuation was taken. Oh, OK. That makes perfect sense, then, and if you want to write introspective code I can see it being really useful. I'll try and make sure you can do it. -- Dan --it's like this--- Dan Sugalski even samurai [EMAIL PROTECTED] have teddy bears and even teddy bears get drunk
Re: What's MY.line?
At 11:52 PM -0400 7/10/02, Chip Salzenberg wrote: According to Dan Sugalski: One pad per block, rather than per sub. Because, of course, all blocks are subs. Got it. Yep. (Well, modulo optimizations of course ;) The place where you'll run into problems in where you have multiple variables of the same name at the same level, which you can do in perl 5. That's more problematic, and I don't think we're going to allow that. -- Dan --it's like this--- Dan Sugalski even samurai [EMAIL PROTECTED] have teddy bears and even teddy bears get drunk
Re: What's MY.line?
According to Dave Mitchell:
Based on what I rememeber from the long threads about this,
Ouch. I gather, then, that nntp.perl.org does not house complete list
archives, or else the discussion was not on p6-language ... ?
sub import {
caller(1).MY{'foo'} = sub { ... };
}
Got it.
--
Chip Salzenberg - a.k.a. -[EMAIL PROTECTED]
It furthers one to have somewhere to go.
Re: What's MY.line?
According to Dan Sugalski: One pad per block, rather than per sub. Because, of course, all blocks are subs. Got it. -- Chip Salzenberg - a.k.a. -[EMAIL PROTECTED] It furthers one to have somewhere to go.
Re: What's MY.line?
On Thu, Jul 11, 2002 at 10:41:20AM -0400, Dan Sugalski wrote: The place where you'll run into problems in where you have multiple variables of the same name at the same level, which you can do in perl 5. can it? can you give an example? -- In England there is a special word which means the last sunshine of the summer. That word is spring.
Re: What's MY.line?
On Wed, Jul 10, 2002 at 11:57:02PM -0400, Chip Salzenberg wrote: According to Dave Mitchell: Based on what I rememeber from the long threads about this, Ouch. I gather, then, that nntp.perl.org does not house complete list archives, or else the discussion was not on p6-language ... ? don't know about nntp, but see for example, http:[EMAIL PROTECTED]/msg08203.html -- You live and learn (although usually you just live).
Re: What's MY.line?
At 7:18 PM +0100 7/11/02, Dave Mitchell wrote: On Thu, Jul 11, 2002 at 10:41:20AM -0400, Dan Sugalski wrote: The place where you'll run into problems in where you have multiple variables of the same name at the same level, which you can do in perl 5. can it? Yes. can you give an example? [localhost:~] dan% perl my $foo = 12; print $foo; my $foo = ho; print $foo; 12ho[localhost:~] dan% -- Dan --it's like this--- Dan Sugalski even samurai [EMAIL PROTECTED] have teddy bears and even teddy bears get drunk
Re: What's MY.line?
On Thu, Jul 11, 2002 at 02:29:08PM -0400, Dan Sugalski wrote: At 7:18 PM +0100 7/11/02, Dave Mitchell wrote: On Thu, Jul 11, 2002 at 10:41:20AM -0400, Dan Sugalski wrote: The place where you'll run into problems in where you have multiple variables of the same name at the same level, which you can do in perl 5. can it? Yes. can you give an example? [localhost:~] dan% perl my $foo = 12; print $foo; my $foo = ho; print $foo; 12ho[localhost:~] dan% ah, I see what you mean. I hope that'll be a syntax error rather than just a warning in perl6. -- Strange women lying in ponds distributing swords is no basis for a system of government. Supreme executive power derives from a mandate from the masses, not from some farcical aquatic ceremony. Dennis - Monty Python and the Holy Grail.
Re: What's MY.line?
At 2:47 PM -0400 7/11/02, Chip Salzenberg wrote:
According to Dan Sugalski:
At 9:50 PM -0400 7/9/02, Chip Salzenberg wrote:
3a. If so, how can one distinguish among the e.g. many Cmy $foo
variables declared within the current function?
One pad per block, rather than per sub.
I just remembered why I thought that woundn't work: BEGIN is a block.
my $x = 1;
BEGIN { %MY::{'$y'} = \$x }
print $y;
So what do I need to make this aliasing work? C%OUTER::MY::?
Yup. Or caller, or something. I'm not sure what Larry's planning on
for the syntax.
--
Dan
--it's like this---
Dan Sugalski even samurai
[EMAIL PROTECTED] have teddy bears and even
teddy bears get drunk
Re: What's MY.line?
At 7:35 PM +0100 7/11/02, Dave Mitchell wrote: On Thu, Jul 11, 2002 at 02:29:08PM -0400, Dan Sugalski wrote: At 7:18 PM +0100 7/11/02, Dave Mitchell wrote: On Thu, Jul 11, 2002 at 10:41:20AM -0400, Dan Sugalski wrote: The place where you'll run into problems in where you have multiple variables of the same name at the same level, which you can do in perl 5. can it? Yes. can you give an example? [localhost:~] dan% perl my $foo = 12; print $foo; my $foo = ho; print $foo; 12ho[localhost:~] dan% ah, I see what you mean. I hope that'll be a syntax error rather than just a warning in perl6. Me too, since it makes pulling lexicals out by name rather tricky. Doable, but tricky. (And messy, and somewhat expensive) That's Larry's call, though. -- Dan --it's like this--- Dan Sugalski even samurai [EMAIL PROTECTED] have teddy bears and even teddy bears get drunk
Re: What's MY.line?
According to Dan Sugalski:
At 9:50 PM -0400 7/9/02, Chip Salzenberg wrote:
3a. If so, how can one distinguish among the e.g. many Cmy $foo
variables declared within the current function?
One pad per block, rather than per sub.
I just remembered why I thought that woundn't work: BEGIN is a block.
my $x = 1;
BEGIN { %MY::{'$y'} = \$x }
print $y;
So what do I need to make this aliasing work? C%OUTER::MY::?
--
Chip Salzenberg - a.k.a. -[EMAIL PROTECTED]
It furthers one to have somewhere to go.
Re: What's MY.line?
On Thu, Jul 11, 2002 at 02:29:08PM -0400, Dan Sugalski wrote: At 7:18 PM +0100 7/11/02, Dave Mitchell wrote: On Thu, Jul 11, 2002 at 10:41:20AM -0400, Dan Sugalski wrote: The place where you'll run into problems in where you have multiple variables of the same name at the same level, which you can do in perl 5. can it? Yes. can you give an example? [localhost:~] dan% perl my $foo = 12; print $foo; my $foo = ho; print $foo; 12ho[localhost:~] dan% Of course it's a -w warning now: my variable $foo masks earlier declaration in same scope at - line 3. and I can imagine it becoming a mandatory warning in later versions of perl5 (and/or perhaps in future they'll be a way to enable warnings relevant to migration to perl6). Tim.
Re: What's MY.line?
On Thursday 11 July 2002 11:47 am, Chip Salzenberg wrote:
According to Dan Sugalski:
At 9:50 PM -0400 7/9/02, Chip Salzenberg wrote:
3a. If so, how can one distinguish among the e.g. many Cmy $foo
variables declared within the current function?
One pad per block, rather than per sub.
I just remembered why I thought that woundn't work: BEGIN is a block.
my $x = 1;
BEGIN { %MY::{'$y'} = \$x }
print $y;
Even worse, you should be able to modify lexicals even outside your scope.
sub violate_me {
caller(1).MY{'$y'} := caller(1).MY{'$x'};# hypothetical syntax
}
{
my $x = 1;
my $y; # Might be able to BEGIN { violate_me() } instead
violate_me();
print $y;
}
Ashley Winters
--
When you do the community's rewrite, try to remember most of us are idiots.
%MY (was What's MY.line?)
At 01:08 PM 7/11/2002 -0700, Ashley Winters wrote:
On Thursday 11 July 2002 11:47 am, Chip Salzenberg wrote:
According to Dan Sugalski:
At 9:50 PM -0400 7/9/02, Chip Salzenberg wrote:
3a. If so, how can one distinguish among the e.g. many Cmy $foo
variables declared within the current function?
One pad per block, rather than per sub.
I just remembered why I thought that woundn't work: BEGIN is a block.
my $x = 1;
BEGIN { %MY::{'$y'} = \$x }
print $y;
Even worse, you should be able to modify lexicals even outside your scope.
sub violate_me {
caller(1).MY{'$y'} := caller(1).MY{'$x'};# hypothetical syntax
}
{
my $x = 1;
my $y; # Might be able to BEGIN { violate_me() } instead
violate_me();
print $y;
}
This reminds me why I don't use Perl4 'local' anymore.
And now we have even uglier ways to write poor code. :)
The only real use I can see of %MY is debugging. If people are going
to take handles to pads and modify lexicals in closures, continuations
and routines from the outside, it probably means that the item needs to
be a class.
And side effects like I call you, you modify me invisibly seems
more like taking dangerous drugs than programming.
Yep, I warned you about calling that routine, now look what it did to
your brains.
-Melvin
Re: What's MY.line?
At 9:18 PM +0100 7/11/02, Tim Bunce wrote: On Thu, Jul 11, 2002 at 02:29:08PM -0400, Dan Sugalski wrote: At 7:18 PM +0100 7/11/02, Dave Mitchell wrote: On Thu, Jul 11, 2002 at 10:41:20AM -0400, Dan Sugalski wrote: The place where you'll run into problems in where you have multiple variables of the same name at the same level, which you can do in perl 5. can it? Yes. can you give an example? [localhost:~] dan% perl my $foo = 12; print $foo; my $foo = ho; print $foo; 12ho[localhost:~] dan% Of course it's a -w warning now: my variable $foo masks earlier declaration in same scope at - line 3. Yep, that's warned for as long as I can remember, though that isn't all that long, I suppose. Still, it's valid. Wonder how many people do that now, completely by accident... and I can imagine it becoming a mandatory warning in later versions of perl5 (and/or perhaps in future they'll be a way to enable warnings relevant to migration to perl6). I'd hope that it would be one of the things we wouldn't support in the perl 5 to perl 6 migration tool. Since it's likely always (or darned close to always) an error, I don't think it'll be a big problem. -- Dan --it's like this--- Dan Sugalski even samurai [EMAIL PROTECTED] have teddy bears and even teddy bears get drunk
Re: What's MY.line?
On Thu, Jul 11, 2002 at 03:18:27PM -0400, Dan Sugalski wrote:
At 7:35 PM +0100 7/11/02, Dave Mitchell wrote:
On Thu, Jul 11, 2002 at 02:29:08PM -0400, Dan Sugalski wrote:
At 7:18 PM +0100 7/11/02, Dave Mitchell wrote:
On Thu, Jul 11, 2002 at 10:41:20AM -0400, Dan Sugalski wrote:
The place where you'll run into problems in where you have multiple
variables of the same name at the same level, which you can do in
perl 5.
can it?
Yes.
can you give an example?
[localhost:~] dan% perl
my $foo = 12;
print $foo;
my $foo = ho;
print $foo;
12ho[localhost:~] dan%
ah, I see what you mean. I hope that'll be a syntax error rather than just
a warning in perl6.
Me too, since it makes pulling lexicals out by name rather tricky.
Doable, but tricky. (And messy, and somewhat expensive) That's
Larry's call, though.
Is there any specific case where you can't treat
{
my $foo = 12;
print $foo;
my $foo = ho;
print $foo;
}
as
{
my $foo = 12;
print $foo;
{
my $foo = ho;
print $foo;
}
}
(where my outer {}s may just be the scope represented by the beginning and end
of the file)
ie implicitly start a new block just before any duplicate my, which continues
until the point the current block ends.
Nicholas Clark
--
Even better than the real thing:http://nms-cgi.sourceforge.net/
Re: What's MY.line?
On Thu, Jul 11, 2002 at 10:37:27PM +0100, Nicholas Clark wrote:
Is there any specific case where you can't treat
{
my $foo = 12;
print $foo;
my $foo = ho;
print $foo;
}
as
{
my $foo = 12;
print $foo;
{
my $foo = ho;
print $foo;
}
}
Well, it B*gg*rs up %MY::
The currently planned semantics are:
{
my $x;
exists %MY::{'$x'}; # true;
}
and
{
my $x;
{
exists %MY::{'$x'}; # false
}
}
so consider:
{
my $x;
my $dup;
my $dup;
exists %MY::{'$x'}; # true?
}
which invisibly becomes
{
my $x;
my $dup;
{
my $dup;
exists %MY::{'$x'}; # false?
}
}
--
But Sidley Park is already a picture, and a most amiable picture too.
The slopes are green and gentle. The trees are companionably grouped at
intervals that show them to advantage. The rill is a serpentine ribbon
unwound from the lake peaceably contained by meadows on which the right
amount of sheep are tastefully arranged. Lady Croom - Arcadia
Re: What's MY.line?
At 11:45 PM +0100 7/11/02, Dave Mitchell wrote:
On Thu, Jul 11, 2002 at 10:37:27PM +0100, Nicholas Clark wrote:
Is there any specific case where you can't treat
{
my $foo = 12;
print $foo;
my $foo = ho;
print $foo;
}
as
{
my $foo = 12;
print $foo;
{
my $foo = ho;
print $foo;
}
}
Well, it B*gg*rs up %MY::
True, but if we're only worrying about it for perl 5 code being
translated, it's not a big deal since it won't be using %MY.
--
Dan
--it's like this---
Dan Sugalski even samurai
[EMAIL PROTECTED] have teddy bears and even
teddy bears get drunk
Re: %MY (was What's MY.line?)
At 4:43 PM -0400 7/11/02, Melvin Smith wrote: The only real use I can see of %MY is debugging. If people are going to take handles to pads and modify lexicals in closures, continuations and routines from the outside, it probably means that the item needs to be a class. Yeah, I'm expecting it to be used mainly for introspective things. It's also useful, at compile time, for changing the caller's environment, but that's not what we're worried about, I expect. -- Dan --it's like this--- Dan Sugalski even samurai [EMAIL PROTECTED] have teddy bears and even teddy bears get drunk
What's MY.line?
In (re?)examining the Apocalypses, I've found something that confuses me a
bit. A2 refers to CMY as a pseudopackage and says:
__LINE__ becomes MY.line
__FILE__MY.file
There is also Apocalypsal reference to C%MY as a name for the current
lexical symbol table.
First:
1. Is there any technical connection between CMY and C%MY?
I don't think there has to be. (Though I suppose you could
play entertaining tricks by manipulating C%MY{MY}.)
With regard to CMY:
2. What are line and file? Properties? Class variables?
(Probably not class variables since CMY is not called a class.)
And with regard to C%MY: Each function in Perl 5 has a single PAD that
could correspond to C%MY, except that PAD entries are indexed by a
combination of name and statement range. So:
3. Is C%MY intended to reflect the PAD?
3a. If so, how can one distinguish among the e.g. many Cmy $foo
variables declared within the current function?
3b. If not, how are lexical adjustments to C%MY unwound? Or are
they? If they're not, I can actually see the idea that could be
part of the base utility of C%MY.
3b1. But if they're not unwound, then the changes that *are* unwound
don't live in C%MY! For example:
if foo() { my $x = 1; print $x }
if bar() { my $x = 2; print $x }
The comings and goings of C$x in this code can't be
represented in C%MY (unless answer #3 above is yes,
in which case this branch of questions is void).
Larry? Damian? Allison? (Chief? McCloud?)
--
Chip Salzenberg - a.k.a. -[EMAIL PROTECTED]
It furthers one to have somewhere to go.
Re: What's MY.line?
On Tue, Jul 09, 2002 at 09:50:26PM -0400, Chip Salzenberg wrote:
Based on what I rememeber from the long threads about this,
3. Is C%MY intended to reflect the PAD?
loosely speaking yes.
3a. If so, how can one distinguish among the e.g. many Cmy $foo
variables declared within the current function?
It was decreed that %MY only sees stuff in the inner-most lexical scope
(so the Perl6 version of a pad is 'bigger' than what %MY sees):
{
my $x = 1;
{
exists %MY::{'$x'}; # false
print %MY::{'$x'}; # undef
print $x; # 1
%MY{'$x'} = 2;
print %MY::{'$x'}; # 2
print $x; # 2
{
exists %MY::{'$x'}; # false
print %MY::{'$x'}; # undef
print $x; # 2
}
}
exists %MY::{'$x'}; # true
print %MY::{'$x'}; # 1
print $x; # 1
}
3b. If not, how are lexical adjustments to C%MY unwound? Or are
they? If they're not, I can actually see the idea that could be
part of the base utility of C%MY.
I think the main intent of %MY:: is to allow import() to lexically affect
the caller, ie
sub import {
caller(1).MY{'foo'} = sub { ... };
}
(for some vague handwaving interpretation of caller() and MY)
Dave.
--
My get-up-and-go just got up and went.
Re: What's MY.line?
At 9:50 PM -0400 7/9/02, Chip Salzenberg wrote: 3. Is C%MY intended to reflect the PAD? Yes. 3a. If so, how can one distinguish among the e.g. many Cmy $foo variables declared within the current function? One pad per block, rather than per sub. -- Dan --it's like this--- Dan Sugalski even samurai [EMAIL PROTECTED] have teddy bears and even teddy bears get drunk
Re: What's MY.line?
At 04:24 PM 7/10/2002 +0100, [EMAIL PROTECTED] wrote:
Dan Sugalski [EMAIL PROTECTED] writes:
At 9:50 PM -0400 7/9/02, Chip Salzenberg wrote:
3. Is C%MY intended to reflect the PAD?
Yes.
Hey! How's this for a scary thought:
$continuation.the_pad
I'll get my coat.
Hah, good try!
I think this would be easy for Parrot. A continuation object will
have all of its context encapsulated already, including the lexical pad
stack.
Assuming the existence of this mystical beast, it could work like:
%continuation.the_pad{'$foo'}
-Melvin
Re: What's MY.line?
Chip Salzenberg wrote in perl.perl6.language : In (re?)examining the Apocalypses, I've found something that confuses me a bit. A2 refers to CMY as a pseudopackage and says: __LINE__ becomes MY.line __FILE__MY.file [...] With regard to CMY: 2. What are line and file? Properties? Class variables? (Probably not class variables since CMY is not called a class.) That's the implementation problem ;-) In perl 5, __LINE__, __FILE__ and __PACKAGE__ are replaced at compile-time (in fact, at tokenizing-time) by the appropriate constants. The question is : to which kind of bytecode MY.file (etc.) get compiled ? -- Rafael Garcia-Suarez : http://use.perl.org/~rafael/
Re: What's MY.line?
At 4:24 PM +0100 7/10/02, [EMAIL PROTECTED] wrote: Dan Sugalski [EMAIL PROTECTED] writes: At 9:50 PM -0400 7/9/02, Chip Salzenberg wrote: 3. Is C%MY intended to reflect the PAD? Yes. Hey! How's this for a scary thought: $continuation.the_pad What's that supposed to do, though? You want to alter the pad that gets put in place at the top of the pad list for a continuation? No problem. A bad idea, mind, but no problem... :) -- Dan --it's like this--- Dan Sugalski even samurai [EMAIL PROTECTED] have teddy bears and even teddy bears get drunk
Re: What's MY.line?
At 10:12 PM + 7/10/02, Rafael Garcia-Suarez wrote: Chip Salzenberg wrote in perl.perl6.language : In (re?)examining the Apocalypses, I've found something that confuses me a bit. A2 refers to CMY as a pseudopackage and says: __LINE__ becomes MY.line __FILE__MY.file [...] With regard to CMY: 2. What are line and file? Properties? Class variables? (Probably not class variables since CMY is not called a class.) That's the implementation problem ;-) In perl 5, __LINE__, __FILE__ and __PACKAGE__ are replaced at compile-time (in fact, at tokenizing-time) by the appropriate constants. The question is : to which kind of bytecode MY.file (etc.) get compiled ? Well, unless they're accessible symbollically, there's no difference between __LINE__ and MY.line. Just string constants to compare against... -- Dan --it's like this--- Dan Sugalski even samurai [EMAIL PROTECTED] have teddy bears and even teddy bears get drunk
