Re: Re: what does shift do?

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Re: Re: Re: what does shift do? by Juerd (Abbot) on May 19, 2002 at 20:48 UTC
`sub greet { my $name = shift; print "Hello, $name\n"; } greet('dev2000');` [download] In mod_perl, with Apache::Registry, your script is cached in a sub, and that sub gets the Apache object as its argument. You could of course write this: `$_[0]->send_http_header('text/plain'); $_[0]->print("mod_perl rules!\n");` [download] But it's easier to have a named variable for that, especially when you use other subs and your `@_` gets overwritten. Back to the point, your script: `my $r = shift; ...` [download] is wrapped in a sub so it can be cached: `package Some::URL::Based::Package::Name;use Apache qw(exit);sub handle +r { #line 1 script.pl my $r = shift; ... }` [download] And suddenly, it all makes sense. - Yes, I reinvent wheels. - Spam: Visit eurotraQ.	[reply] [d/l] [select]
Re(2): what does shift do? by dmmiller2k (Chaplain) on May 19, 2002 at 20:41 UTC
Because `$r` is being used as an object, by calling its `send_http_header()` and `print()` methods. Without the shift (I presume this is inside a subroutine), the object represented by the reference `$r` would never be referenced and the code would not work. P.S., without seeing the context in which your example lives, it I do not exactly know what kind of object `$r` is , but from its method names, I suspect it's one of the Http::XXX'en. dmm If you GIVE a man a fish you feed him for a day But, TEACH him to fish and you feed him for a lifetime	[reply] [d/l] [select]
Re: Re(2): what does shift do? by Juerd (Abbot) on May 19, 2002 at 20:52 UTC
P.S., without seeing the context in which your example lives, it I do not exactly know what kind of object $r is , but from its method names, I suspect it's one of the Http::XXX'en. The context is mod_perl, and probably Apache::Registry, which wraps scripts in subs for caching. - Yes, I reinvent wheels. - Spam: Visit eurotraQ.	[reply]