From: [EMAIL PROTECTED]
To: David L. Nicol [EMAIL PROTECTED]
Sent: Friday, June 08, 2001 8:01 PM
Subject: Re: Properties and stricture and capabilities
On Thu, Jun 07, 2001 at 08:24:33PM -0500, David L. Nicol wrote:
That would prevent further shoving of anything onto the symbol table
without
On Thu, Jun 07, 2001 at 08:24:33PM -0500, David L. Nicol wrote:
Symbol table manipulation will work as long as your mucking about
doesn't alter the strict class's signature. ie. you can shove a code
ref onto the symbol table as long as a stub for that method was
defined at compile time.
Ok, I've realized a few things.
1) There's two sorts of type-checking going on here. Compile-time and
run-time.
2) Run-time type checking is fairly easy and imposes few limitations. In
fact, you can even do it now through ad hockery.
3) Compile-time type checking is a bit harder. Any
On Wed, Jun 06, 2001 at 10:28:41AM -0400, John Porter wrote:
Michael G Schwern wrote:
It will have to go for strict classes. @ISA will have to be locked.
strict classes?
strongly typed class?
Can a man make up gibberish in peace? ;)
Basically, any class which wants to be type-checked at
On Wed, Jun 06, 2001 at 07:06:49PM -0700, Dave Storrs wrote:
But if we did, how could we hope to get a good new Star Trek
series? :
You're still hoping for a new, good Star Trek series??? You must be a
Cubs fan.
--
Michael G. Schwern [EMAIL PROTECTED]
On Wed, Jun 06, 2001 at 01:37:23AM -0500, Me wrote:
BD languages
What's BD?
Bondage and Discipline, scum! You're not a good enough programmer to
be trusted not to make mistakes! Now drop and give me fifty!
--
Michael G. Schwern [EMAIL PROTECTED]http://www.pobox.com/~schwern/
Michael G Schwern wrote:
Basically, any class which wants to be type-checked at compile time.
I think the meaning of that is still not clear,
given what strong typing usually means.
--
John Porter
Michael G Schwern wrote:
you can even do it now through ad hockery.
Or odd hackery.
:-)
--
John Porter
This is similar to the solution they use in Java. You have an interface,
which is compile time checked. Then, when you load a class at runtime, you
check at load time that it satisfies the interface. You either get an
exception right then, or you're fine.
Daniel
Michael G Schwern wrote:
On Wed, Jun 06, 2001 at 01:37:23AM -0500, Me wrote:
Larry's MMV on that ;-)
Man I really need to get up to speed with these
acronyms. I know YMMV, is MMV a distant
cousin perhaps?
Same idea, except it's Larry's Milage in question, rather than Yours.
dha
--
David H. Adler - [EMAIL
Michael G Schwern wrote:
Symbol table manipulation will work as long as your mucking about
doesn't alter the strict class's signature. ie. you can shove a code
ref onto the symbol table as long as a stub for that method was
defined at compile time.
a read-only hash of any kind makes it
And, if this is so, then isn't it impossible to have useful
stricture about variable properties, because any given
reference to a property might be instead a value property
unknown to the compiler?
Yes.
So:
You can't have (variable or value) property stricture.
Do
Daniel S. Wilkerson [EMAIL PROTECTED] writes:
Michael G Schwern wrote:
No subroutine refs. No dynamic inheritance. No autoloading. No
dynamic method calls. No symbol table manipulation. No eval. No
automatic method generation. (That's off the top of my head).
You don't loose all
Michael G Schwern [EMAIL PROTECTED] writes:
Consider the following... Foo is a poster-child for a strict class.
Everything is predeclared and typed. Its entire hierarchy is rock
solid. Someone uses Foo in their script and calls Foo-bar. They
also use Bar, a module you installed a long time
Michael G Schwern wrote:
It will have to go for strict classes. @ISA will have to be locked.
strict classes?
my $meth = foo;
$obj-$meth(); # $obj-foo();
This definately can't work if $obj is of a class which is strongly
typed.
strongly typed class?
This can still work
[strict typing]
Not a negative, but realize that many people find it
of less value than the annoyances it brings with it
(myself included)
Michael, I don't know which is more impressive; the
fact that use of a strictly typed language implies that
a copy of you would land on the poor
Me wrote:
[strict typing]
Not a negative, but realize that many people find it
of less value than the annoyances it brings with it
(myself included)
Michael, I don't know which is more impressive; the
fact that use of a strictly typed language implies that
a copy of you would
Me wrote:
I.Found your notion of a sealed off namespace
intriguing. I have no idea what it meant just yet;
I'm going to go read and think about it now.
I'll pitch some syntax:
# prevent modification to %reflexive:: like so:
package reflexive is closed;
# allow it
Me wrote:
Question 1:
Afaict, even with use strict at its most strict, perl 6
can't (in practice) complain, at compile time, if
$foo.Foun
refers to an undeclared Foun.
Right?
it is already detectable. from perldoc perlref:
Perl will raise an exception if you
Afaict, even with use strict at its most strict, perl 6
can't (in practice) complain, at compile time, if
$foo.Foun
refers to an undeclared Foun.
it is already detectable. from perldoc perlref:
Perhaps for perl 5, but, aiui, Damian confirmed
that my thinking about
On Tue, 5 Jun 2001, Michael G Schwern wrote:
On Tue, Jun 05, 2001 at 01:34:35PM -0700, Daniel S. Wilkerson wrote:
I cannot imagine running an enterprise critical application
As a complete digression, can we please strike the term enterprise
from the English lexicon? Completely
On Mon, Jun 04, 2001 at 06:49:28PM -0500, Me wrote:
Afaict, even with use strict at its most strict, perl 6
can't (in practice) complain, at compile time, if
$foo.Foun
refers to an undeclared Foun.
Right?
Should there be a strict mode that warns if a
method name matches
On Tue, 5 Jun 2001 [EMAIL PROTECTED] wrote:
So I'd say no, Perl can't know at compile-time if your method is
declared or not. Only in certain restricted cases, such as if you
don't inherit from anything, or if *all* your parent classes are
declared strictly.
(By 'strictly', I
I would like to suggest that this is one of the major advantages that Java
has over Perl. Getting things to work quickly in Perl is great. I like
that very much about Perl. But in the end, I'm most concerned that my code
is correct. Having the compiler check everything it can possibly check
Perl has strong typing; it just has a different notion of
what a type is. The types in Perl are SCALAR, ARRAY,
HASH, CODE, and a few others. Watch:
% perl -e 'sub foo(\@){} foo %h'
Type of arg 1 to main::foo must be array (not hash deref) at -e line 1, at EOF
Execution of -e aborted due to
On Tue, Jun 05, 2001 at 11:51:53AM -0400, John Porter wrote:
Perl has strong typing; it just has a different notion of
what a type is. The types in Perl are SCALAR, ARRAY,
HASH, CODE, and a few others. Watch:
% perl -e 'sub foo(\@){} foo %h'
Type of arg 1 to main::foo must be array (not
On Tue, Jun 05, 2001 at 08:24:31AM -0700, Daniel S. Wilkerson wrote:
But in the end, I'm most concerned that my code is correct. Having
the compiler check everything it can possibly check for me is really
a requirement for that. Compile time type checking of method
signatures is really
Michael G Schwern wrote:
Prototypes don't work on methods. And I wouldn't hold them up as
being anything but a mediocre hack. Its not really type checking.
It's not just prototypes.
% perl -e '$r=\%h; print @$r'
Not an ARRAY reference at -e line 1.
Of course, that's a run-time check, but
On Tue, Jun 05, 2001 at 07:33:55AM -0700, Dave Storrs wrote:
(By 'strictly', I think you mean 'all methods (etc) are declared
explicitly in code, not generated by AUTOLOAD, etc'. If I'm not
understanding you correctly, please correct me.)
Yeah, pretty much. I put together a
On Tue, Jun 05, 2001 at 12:46:52PM -0400, John Porter wrote:
Michael G Schwern wrote:
Prototypes don't work on methods. And I wouldn't hold them up as
being anything but a mediocre hack. Its not really type checking.
It's not just prototypes.
% perl -e '$r=\%h; print @$r'
Not an
At 07:29 PM 6/5/01 +0100, Michael G Schwern wrote:
Consider the following... Foo is a poster-child for a strict class.
Everything is predeclared and typed. Its entire hierarchy is rock
solid. Someone uses Foo in their script and calls Foo-bar. They
also use Bar, a module you installed a long
Michael G Schwern wrote:
% perl -e '$r=\%h; print @$r'
Not an ARRAY reference at -e line 1.
This isn't type-checking (semantical arguments /dev/null),
Heed your own redirection, eh?
its more like basic syntax.
No, it's not. If it were, then it would be caught at
compile time.
You
On Tue, Jun 05, 2001 at 02:42:01PM -0400, John Porter wrote:
You don't want to try holding up prototypes and dereference checks to
Java's typing system and try to claim its in the same league, or even
the same sport.
As I said before, it boils down to the fact that perl's notion of a
From: Michael G Schwern [mailto:[EMAIL PROTECTED]]
Before anyone gets the wrong idea, I don't think the solution is a
drastic scaling back in Perl's flexibility. I just don't know what
the solution is yet. Maybe it should be possible for a class to
completely seal off its namespace to the
I can't imagine any way in which one can consider Perl typing to be strong.
When you know the type of a variable, you are supposed to have confidence that
when you see a statement
a - lexically locally (without looking around elsewhere) and
b - at compile time
you know exactly what the statement
On Tue, Jun 05, 2001 at 02:37:11PM -0500, Garrett Goebel wrote:
Before anyone gets the wrong idea, I don't think the solution is a
drastic scaling back in Perl's flexibility. I just don't know what
the solution is yet. Maybe it should be possible for a class to
completely seal off its
On Tue, Jun 05, 2001 at 01:05:45PM -0700, Daniel S. Wilkerson wrote:
2 - You can't make a user defined type, like classes in Java, that
are compile time checked.
Well, you can sort of: Attribute::Types. But that's not what John is
talking about.
--
Michael G. Schwern [EMAIL PROTECTED]
Michael G Schwern wrote:
On Tue, Jun 05, 2001 at 08:24:31AM -0700, Daniel S. Wilkerson wrote:
But in the end, I'm most concerned that my code is correct. Having
the compiler check everything it can possibly check for me is really
a requirement for that. Compile time type checking of
Michael G Schwern [mailto:[EMAIL PROTECTED]] wrote:
Of course, there's problems of order of definition. What happens if
Bar.pm is loaded before Foo? Dunno.
simple sematics can be defined. If we see a declaration:
package Foo is encapulated;
then we throw an error if the namespace, Foo,
Daniel S. Wilkerson wrote:
I can't imagine any way in which one can consider Perl typing to be strong.
When you know the type of a variable, you are supposed to have confidence
that when you see a statement
a - lexically locally (without looking around elsewhere) and
b - at compile time
you
I would like to see some sort of use really_strict pragma which would
disable at compile time the kinds of things you mentioned:
Yes, the point is to make this possible, not required. I thought Perl was
supposed to make hard things possible. This is easy in Java and its not
even possible in
Daniel S. Wilkerson wrote:
Michael G Schwern wrote:
Type checking is nice, but its just one class of error-checking.
Doesn't do squat for basic logic errors, for example.
No, it does.
I think you're missing what ought to be an obvious point:
No amount of (sane) typing will allow your
If you call a method in Java, you can see right there which method you are
calling. You can then lexically follow the inheritance tree and find out exactly
what code really is called, what its signature is, and what it returns. Nothing
dynamic is involved.
One might ask for other featues, but
On Tue, Jun 05, 2001 at 01:42:38PM -0700, Daniel S. Wilkerson wrote:
Someone please tell me what automatic method generation is exactly.
Its the generation of large numbers of similar methods which would
otherwise be really tedious to write out by hand, such as accessor
methods. Without this,
On Tue, Jun 05, 2001 at 01:42:38PM -0700, Daniel S. Wilkerson wrote:
Someone please tell me what automatic method generation is exactly.
package Foo;
sub AUTOLOAD {
my $method = $AUTOLOAD;
eval sub $method { warn qq/Please do not call this method again.\n/ }
goto $method;
}
--
I
Thank you, that's what I thought it might be. This can be done at compile time with a
two-stage
compilation. The first one writes the code that the second compiles. Then the
checking can be
done during the second stage.
Daniel
Michael G Schwern wrote:
On Tue, Jun 05, 2001 at 01:42:38PM
I apologize. I royally screwed up my original post.
I had meant to ask two minor specific yes/no answer
type questions about properties and stricture, that
were mutually unrelated. Instead I asked one major
open ended one.
In the hope that I haven't completely blown any
chance of getting
At 02:39 PM 6/5/2001 -0700, Daniel S. Wilkerson wrote:
Thank you, that's what I thought it might be. This can be done at compile
time with a two-stage
compilation. The first one writes the code that the second
compiles. Then the checking can be
done during the second stage.
Not when the
Daniel S. Wilkerson wrote:
It is doubtful we shall have compilers that can tell you for example,
that you used the wrong algorithm.
Right. I think that's what Schwern was getting at, when he said
Type checking is nice, but its just one class of error-checking.
By preventing lots of
On Tue, Jun 05, 2001 at 01:34:35PM -0700, Daniel S. Wilkerson wrote:
I cannot imagine running an enterprise critical application
As a complete digression, can we please strike the term enterprise
from the English lexicon? Completely redundant and drives me up the
wall. Almost as bad as
On Tue, Jun 05, 2001 at 02:39:33PM -0700, Daniel S. Wilkerson wrote:
Thank you, that's what I thought it might be. This can be done at
compile time with a two-stage compilation. The first one writes the
code that the second compiles. Then the checking can be done during
the second stage.
John Porter wrote:
Daniel S. Wilkerson wrote:
It is doubtful we shall have compilers that can tell you for example,
that you used the wrong algorithm.
Right. I think that's what Schwern was getting at, when he said
Type checking is nice, but its just one class of error-checking.
On Tue, Jun 05, 2001 at 05:49:30PM -0400, John Porter wrote:
By preventing lots of little gotchas, you free the mind to pay attention
to what it is doing rather than the most minute details of how to do
it. This is a quite powerful effect.
Interesting you should mention this.
It is,
On Tue, Jun 05, 2001 at 03:29:02PM -0700, Daniel S. Wilkerson wrote:
It would be interesting for someone to measure that, however I doubt that it
is so.
Oh, and look at what just showed up in my mailbox!
- Forwarded message from Tony Bowden [EMAIL PROTECTED] -
I think we should start
On Tue, Jun 05, 2001 at 04:38:24PM -0500, Me wrote:
Question 1:
Afaict, even with use strict at its most strict, perl 6
can't (in practice) complain, at compile time, if
$foo.Foun
refers to an undeclared Foun.
Right?
Can't you hear the low roar from the strong-typing
On Tue, Jun 05, 2001 at 11:14:29PM +0100, Michael G Schwern wrote:
my $meth = foo;
$obj-$meth(); # $obj-foo();
I'm probably using the wrong terms.
This definately can't work if $obj is of a class which is strongly
typed.
You would do that in Java by using reflection. There's
Question 1:
Afaict, even with use strict at its most strict, perl 6
can't (in practice) complain, at compile time, if
$foo.Foun
refers to an undeclared Foun.
It could certainly warn you, but it can't object fatally since there's
always the
Question 2:
Afaict, even with use strict at its most strict, perl 6
can't (in practice) complain, at compile time, if
$foo.Foun
refers to an undeclared Foun.
It could certainly warn you
Consider the code:
my $foo = 1 is Found;
On Tue, Jun 05, 2001 at 04:38:24PM -0500, Me wrote:
Question 1:
Afaict, even with use strict at its most strict, perl 6
can't (in practice) complain, at compile time, if
$foo.Foun
refers to an undeclared Foun.
Right?
Can't you hear the low roar from the
Consider the code:
my $foo = 1 is Found;
bar($foo);
sub bar { my $baz = shift; if ($baz.Found) { ...} }
Does the value of $baz have the Found property?
Yes.
If so, does the compiler know that?
No. Because it only has the property at
Consider the code:
my $foo = 1 is Found;
bar($foo);
sub bar { my $baz = shift; if ($baz.Found) { ...} }
Does the value of $baz have the Found property?
Yes.
If so, does the compiler know that?
No. Because it only has the property
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