Re^4: Sigils in Perl 6

And just to add something that is not explained at all in the synopsis, the idea of twigils is actually stolen straight from Ruby, which uses sigils to indicate strange scoping rather than data structure. A lovely idea, but using up sigils for that limits the extensibility of the mechanism, because there aren't that many ASCII symbols left to use in the sigil position that don't already mean something else. But by placing the scope indicator in the twigil position (that is, after a mandatory sigil), we can reserve the rest of the symbol keys on your keyboard to indicate future scopes that maybe haven't even been invented yet. Maybe someone will invent transaction scopes, for instance.

So I think of twigils as just another way of making Perl more like Perl. As with sigils, the primary purpose of twigils is to give you, the reader, a visual clue about what's going on in a bit of code without having to memorize every declaration surrounding this scope. The moment you see something like $?FOO you can know that it's a variable to the compiler but a constant to the compiled code, without having to memorize a list of special symbols, or use weird non-sigil conventions like __FOO__.

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Re^5: Sigils in Perl 6 by ysth (Canon) on May 15, 2007 at 19:01 UTC
So is ^ a perl5 twigil?	[reply]
Re^6: Sigils in Perl 6 by TimToady (Parson) on May 15, 2007 at 19:28 UTC
So is ^ a perl5 twigil? Heh, kinda, except it's almost completely wasted on producing variable names consisting of control characters. The ^ twigil in Perl 6 is rather more useful, I'd like to think. How many times have people been bitten by magical `$a` and `$b` in Perl 5? The ^ twigil fixes that, and more. A goodly many of Perl 6's features can be explained as simply trying to make Perl 5's FAQs into former FAQs.	[reply] [d/l] [select]
Re^7: Sigils in Perl 6 by ysth (Canon) on May 15, 2007 at 20:25 UTC
Now I'm wondering when someone will write a YAPE::Regex::Explain-like module for perl 6 nouns :)	[reply]
Re^7: Sigils in Perl 6 by blazar (Canon) on May 20, 2007 at 11:43 UTC
How many times have people been bitten by magical `$a` and `$b` in Perl 5? While I'm a strong advocate of "do not use `$a` and `$b` as general purpose variables" myself, and I feel like having written so in hundreds of posts... to answer your question literally: "probably fewer than those who have been warned not to!"	[reply] [d/l] [select]
Re^5: Sigils in Perl 6 by jplindstrom (Monsignor) on May 15, 2007 at 19:21 UTC
But by placing the scope indicator in the twigil position (that is, after a mandatory sigil), we can reserve the rest of the symbol keys on your keyboard to indicate future scopes that maybe haven't even been invented yet. Would that mean new twigils can be introduced by application programmers? So, e.g. Catalyst::Controller::BindLex could use this instead of attributes? /J	[reply]
Re^6: Sigils in Perl 6 by duff (Parson) on May 15, 2007 at 19:23 UTC
"All's fair if you predeclare" :-) duff	[reply]


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