passing $_ to my function

arc_of_descent has asked for the wisdom of the Perl Monks concerning the following question:

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Re: passing $_ to my function by broquaint (Abbot) on Sep 30, 2002 at 12:14 UTC
Check if you've got any arguments otherwise default to `$_` e.g `sub def_arg { my $arg = @_ ? shift : $_; print "got: $arg\n"; } $_ = "bar"; def_arg("foo"); def_arg(); __output__ got: foo got: bar` [download] HTH `_________ broquaint`	[reply] [d/l]
Re: passing $_ to my function by moxliukas (Curate) on Sep 30, 2002 at 12:03 UTC
Maybe something along the lines like: `sub my_sub { my $argument = shift \|\| $_; # do things with $argument }` [download] Be warned: I am not a Perl guru though	[reply] [d/l]
Re: Re: passing $_ to my function by davorg (Chancellor) on Sep 30, 2002 at 12:15 UTC
That breaks if you pass an argument that evaluates as false. I'd do something like this: `sub my_sub { my $arg = @_ ? shift : $_; # do stuff }` [download] -- <http://www.dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l]
Re: passing $_ to my function by arc_of_descent (Hermit) on Sep 30, 2002 at 12:47 UTC
Thanx, I got what i wanted. Guess i have to read more about lexical scoping. I had no idea $_ would permeate through the function! -- arc_of_descent	[reply]
Re^2: passing $_ to my function by Aristotle (Chancellor) on Sep 30, 2002 at 13:04 UTC
Actually, this is dynamical scoping (local et al), not lexical (my et al). Makeshifts last the longest.	[reply]
Re: passing $_ to my function by robartes (Priest) on Sep 30, 2002 at 12:13 UTC
You could try using the & form of a subroutine call: `for (keys %online_users) { if (policy_is_expired($_)) { &logoff_user; } }` [download] This form passes @_ to the sub if no arguments are given.	[reply] [d/l]
Re^2: passing $_ to my function by Aristotle (Chancellor) on Sep 30, 2002 at 13:03 UTC
No, that won't work. You're passing `@_`, which is not the same as `$_`. Makeshifts last the longest.	[reply]
Re: passing $_ to my function by blm (Hermit) on Sep 30, 2002 at 14:06 UTC
I usually use `sub my_sub { my ($arg1, $arg2) = @_; ... }` [download] in my functions. So the equivalent of these would be: `sub my_sub { my ($arg1, $arg2) = @_ ? @_ : $_; ... }` [download] Is this reasonable? --blm-- If you don't like this post can you please /msg me	[reply] [d/l] [select]
Re: passing $_ to my function by nutshell (Beadle) on Sep 30, 2002 at 20:17 UTC
Tell me, please, what's wrong with simply using: `for my $i (keys %online_users) { if (policy_is_expired($i)) { logoff_user($i); } }` [download] Or just continuing to use $_? Implanting a work-around is just adding unneeded code.	[reply] [d/l]
Re x 2: passing $_ to my function by Sweeper (Pilgrim) on Oct 01, 2002 at 05:43 UTC
Implanting a work-around is just adding unneeded code. In addition, it is a waste of CPU time (cf Nicholas Clark's talk in Munich) Update: this talk is available at http://www.ccl4.org/~nick/P/Fast_Enough.	[reply]


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