Re: Very[OT]:Technical query re: scratchpad lookups for my() vars

[Elizabeth Mattijsen <li...@dijkmat.nl>]

At 03:52 PM 3/14/01 -0800, Paul wrote:
But nothing about the structural/algorithmic mechanics. :<

 From the perlsub docs:

Variables declared with my are not part of any package and are therefore 
never fully qualified with the package name. In particular, you're not 
allowed to try to make a package variable (or other global) lexical:

     my $pack::var;      # ERROR!  Illegal syntax
     my $_;              # also illegal (currently)
In fact, a dynamic variable (also known as package or global variables) are 
still accessible using the fully qualified :: notation even while a lexical 
of the same name is also visible:

     package main;
     local $x = 10;
     my    $x = 20;
     print "$x and $::x\n";
That will print out 20 and 10.

There is _no_ stash of lexicals during execution, only during 
compilation.  I guess one of the reasons lexicals are faster.


Elizabeth Mattijsen

Re: Very[OT]:Technical query re: scratchpad lookups for my() vars

["Alexander Farber (EED)" <ee...@eed.ericsson.se>]

Paul wrote:
> None of this is critical for anything I'm doing right now, but I'm a
> detail hound. I want to *understand* it, so that in the future I can
> make intelligent decisions about what would be a "better" way to write
> any given algorithm, without just relying on popular wisdom and "urban
> legend". =o)

If you're a "detail hound", why don't you look into the perl source code?

Re: VeryOT: help needed

[Matt Sergeant <ma...@sergeant.org>]

On Thu, 15 Mar 2001, Jauder Ho wrote:

> Alright, it's crunch time (trying to help a coworker out) and I need
> to pick up some XML parsing with perl fast. So if anyone here has some
> good resources, they can point me at, it would be much appreciated.
> 
> The problem I am trying to solve is as follows: I have two XML files, one
> is encoded in UTF8 and the other is in ASCII7. I need to parse the ASCII7
> file first and if a tag exists in the UTF8 file replace the data in the
> ASCII7 file with the UTF8 info. Everything should then be output in a UTF8
> format.
> 
> Pointers to manipulating XML needed but I would take any additional help.
> Thanks.

There is actually a list for perl and xml, for what it's worth, where this
would be on topic... Anyway, I'm going to be totally unbiased here and
suggest you look at XML::XPath. I'm not 100% certain what you're trying to
achieve, but most things are pretty simple with XPath. Contact me offline
if you have further questions.

-- 
<Matt/>

    /||    ** Founder and CTO  **  **   http://axkit.com/     **
   //||    **  AxKit.com Ltd   **  ** XML Application Serving **
  // ||    ** http://axkit.org **  ** XSLT, XPathScript, XSP  **
 // \\| // ** mod_perl news and resources: http://take23.org  **
     \\//
     //\\
    //  \\

VeryOT: help needed

[Jauder Ho <ja...@carumba.com>]

Alright, it's crunch time (trying to help a coworker out) and I need to
pick up some XML parsing with perl fast. So if anyone here has some good
resources, they can point me at, it would be much appreciated.

The problem I am trying to solve is as follows: I have two XML files, one
is encoded in UTF8 and the other is in ASCII7. I need to parse the ASCII7
file first and if a tag exists in the UTF8 file replace the data in the
ASCII7 file with the UTF8 info. Everything should then be output in a UTF8
format.

Pointers to manipulating XML needed but I would take any additional help.
Thanks.

--Jauder

Re: Very[OT]:Technical query re: scratchpad lookups for my() vars

[Paul <yd...@yahoo.com>]

--- Elizabeth Mattijsen <li...@dijkmat.nl> wrote:
> At 03:52 PM 3/14/01 -0800, Paul wrote:
> But nothing about the structural/algorithmic mechanics. :<
> 
>  From the perlsub docs:
> 
> Variables declared with my are not part of any package and are
> therefore 
> never fully qualified with the package name. In particular, you're
> not 
> allowed to try to make a package variable (or other global) lexical:
> 
>      my $pack::var;      # ERROR!  Illegal syntax
>      my $_;              # also illegal (currently)
> In fact, a dynamic variable (also known as package or global
> variables) are 
> still accessible using the fully qualified :: notation even while a
> lexical 
> of the same name is also visible:
> 
>      package main;
>      local $x = 10;
>      my    $x = 20;
>      print "$x and $::x\n";
> That will print out 20 and 10.
> 
> There is _no_ stash of lexicals during execution, only during 
> compilation.  I guess one of the reasons lexicals are faster.
> 
> 
> Elizabeth Mattijsen

An excellent example, all known and understood.
What I can't find is this:

I know that my($x) puts x on this scope's scratchpad (and not in any
package space), but rather than a hash named main:: with a key named x
(which is, as I understand it, an oversimplification perhaps, but
basically what Perl does internally for $main::x), exactly *how* does
Perl "put" x into the scratchpad AV*? and once it's there, what did it
store? How does it know that entry is 'x'? is it just a reference to
the actual value?

None of this is critical for anything I'm doing right now, but I'm a
detail hound. I want to *understand* it, so that in the future I can
make intelligent decisions about what would be a "better" way to write
any given algorithm, without just relying on popular wisdom and "urban
legend". =o)

(That's why I said it was Very[OT], lol....)

Paul

__________________________________________________
Do You Yahoo!?
Yahoo! Auctions - Buy the things you want at great prices.
http://auctions.yahoo.com/