[Mastering-perl] Perl Contexts & Symbol Tables and Typeglobs

[Florian Merges]

Hi again,


2007/1/3, brian d foy <brian.d.foy at gmail.com>:

>

> On 1/2/07, Florian Merges <fmerges at cpan.org> wrote:

> > Ch. Symbol Tables and Typeglobs

> > =========================

> >

> > Section: Package and lexical variables

> > --------------------------------------------------------

> >

> > $n and $global should be declared with 'our'

>

> I've never really been fond of our as a way to declare variables. It's

> useful to bring a package variable into play when a lexical of the

> same name is in scope, but otherwise is just a trick to get around use

> strict. If I really want to make something global, I prefer to list

> them all in 'use vars' :)




Yeah, of course, use vars would be more clean...

However, for those examples I'm specifically avoiding our() until

> later so I don't hit the reader with everything at once.

>

>

> > The first code example, instead of using the 'foreach' idiom, I would

> suggest:

>

> > print join "\n", keys %main::;

>

> I could do that, I guess, but it really doesn't add anything to the

> discussion. In the later example where I check the definedness on the

> var types for each identifier I would have to go back to foreach(), so

> I might as use it in the same way in the preceding examples.



I was thinking about showing more ways to do things, but yes, I took a look
again to the later examples and you're expanding the foreach


>

> >

> > Section: Package and lexical variables -> Full package specification

> >

> --------------------------------------------------------------------------------------------------

> >

> > Last example output should be:

> >

> > In the naked block, our $global is --> I'm the global version

> > In lexical, my $global is --> I'm in the lexical version

> > The package version is still --> I'm the global version

> > In lexical(): I'm the global version

> >

> > Section: The symbol table

> > --------------------------------------

> >

> > The first code example, instead of using the 'foreach' idiom, I would

> > suggest:

> >

> > print join "\n", keys %main::;

> >

> > Section: The symbol table -> Naming anonymous subroutines

> >

> -----------------------------------------------------------------------------------------

> >

> > ..., and then using that function to created two anonymous subroutines.

> >

> > ==> what?

> >

> >




I'm doing a full review picking chapters randomnly, printing them to paper,
and so, but, do you need a review of a specific chapter?, or more
information, examples for a non finished one?



> Kind regards,

> >

> > Florian

> >

> >

> >

> >

> >

> > _______________________________________________

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> >

> >

> >

>

>

> --

> brian d foy <brian.d.foy at gmail.com>

> http://www.pair.com/~comdog/

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>

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