Re^4: Local for lexicals

I'm sorry; I know that I must be mis-using the terms, but it seems to me that what I'm looking for is not contrary to what one could expect of lexicals. Making a change in an inner scope that is ‘seen’ by an outer scope is what I mean by “dynamic scoping” (although I probably shouldn't), and that is, of course, no problem. Having changes to a variable within a scope undone at the end of that scope is just what scoping means—it seems to me that it has nothing to do with lexical vs. dynamic. Again, aside from magic that can be associated to copying,

{
    my $temp = $x; $x = $new;
    ...
    $x = $temp;
}
[download]

does what I want, obviously without subverting Perl in XS-y ways.

Is it really the case that setting aside a value to be restored at the end of scope is what is meant by “dynamic scoping”?

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Re^5: Local for lexicals by JavaFan (Canon) on Aug 10, 2009 at 16:22 UTC
Is it really the case that setting aside a value to be restored at the end of scope is what is meant by “dynamic scoping”? Yes. And package variables allow for dynamic scoping of their values. Lexical variables have lexical scoping. It's that simple. Perl gives you options. Want lexical scoping? Use lexical variables. Want dynamic scoping? Use package variables and local. What's the problem?	[reply]
Re^6: Local for lexicals by doom (Deacon) on Aug 10, 2009 at 21:26 UTC
Is it really the case that setting aside a value to be restored at the end of scope is what is meant by “dynamic scoping”? Yes. Well, sort of... what I would say is the key feature of "dynamic scoping" is that if you call some other sub it sees the current localized value of the variables. E.g. if you do this: `{ local $\="\t"; print_data( \@data ); }` [download] then any `print` statements buried down in the `print_data` sub will now have tabs automatically appended to them. With lexical scoping, if you say `my $some_variable = 1; { my $some_variable = 0; do_some_stuff(); }` [download] then inside the block you get a new variable that happens to have the same name as `$some_variable`, and you see that new variable only inside of the block you're looking at... you don't have to worry about there being any far-ranging effects inside of the sub `do_some_stuff`. Does that help?	[reply] [d/l] [select]
Re^7: Local for lexicals by LanX (Saint) on Aug 10, 2009 at 22:12 UTC
that's how the term is defined in the perldocs: dynamic scoping Dynamic scoping works over a dynamic scope, making variables visible throughout the rest of the block in which they are first used and in any subroutines that are called by the rest of the block. Dynamically scoped variables can have their values temporarily changed (and implicitly restored later) by a local operator. (Compare lexical scoping.) Used more loosely to mean how a subroutine that is in the middle of calling another subroutine "contains" that subroutine at run time. Cheers Rolf	[reply]
Re^6: Local for lexicals by JadeNB (Chaplain) on Aug 10, 2009 at 16:27 UTC
What's the problem? Wanna `local`ise lexicals! Wanna wanna wanna!	[reply] [d/l]