Re: Order of execution of functions in list

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Re^2: Order of execution of functions in list by ikegami (Patriarch) on Sep 13, 2013 at 13:26 UTC
has no side-effects `$ perl -E'@a=qw( a b c ); say 0+@a; shift(@a); say 0+@a;' 3 2` [download] returns an rvalue `$ perl -E'$_=123; say; sub { sub { ++$_[0] }->(shift); }->($_); say;' 123 124` [download]	[reply] [d/l] [select]
Re^3: Order of execution of functions in list by LanX (Saint) on Sep 13, 2013 at 14:05 UTC
The problem with mobiles is that I can't check my code (at least ATM) And I don't understand the sideeffect code you posted. I'll reply this evening... Edit At second glance it seems that shift really returns lvalues... Strange Mea culpa!!! :( Cheers Rolf ( addicted to the Perl Programming Language)	[reply]
Re^3: Order of execution of functions in list by LanX (Saint) on Sep 13, 2013 at 17:02 UTC
> > returns an rvalue FWIW: I think this code is easier to understand and demonstrates your point `DB<194> sub tst { my $x=\(shift()); ++$$x } DB<195> $a=10 => 10 DB<196> tst $a => 11 DB<197> tst $a => 12 DB<198> $a => 12` [download] I get the same results using the equivalent `splice(@_,0,1)` That's not documented in the perldocs for shift or splice and I think it's due to the way Perl holds and replaces variables in @_, they just don't loose their aliasing magic when shifted. Maybe Perl avoids copying of the values for performance reasons. Interesting... But since it's not documented, I doubt that this is reliable behavior. Cheers Rolf ( addicted to the Perl Programming Language)	[reply] [d/l] [select]
Re^4: Order of execution of functions in list by ikegami (Patriarch) on Sep 16, 2013 at 02:08 UTC
But since it's not documented, I doubt that this is reliable behavior. It's an emergent behaviour; it's not by design.	[reply]
Re^5: Order of execution of functions in list ( \(shift @_ ) reference to alias \$_[0] references original ) by Anonymous Monk on Sep 16, 2013 at 03:12 UTC
Re^6: Order of execution of functions in list ( \(shift @_ ) reference to alias \$_[0] references original ) by ikegami (Patriarch) on Sep 20, 2013 at 18:25 UTC
Re^2: Order of execution of functions in list by vsespb (Chaplain) on Sep 13, 2013 at 13:06 UTC
has no side-effects shift() actually modifies @_, isn't it side-effect? if shift()s executed in different order, result will be different.	[reply]
Re^3: Order of execution of functions in list by LanX (Saint) on Sep 13, 2013 at 14:00 UTC
Imho a main effect cause its a builtin function. Do you expect `sub inc { return $_[0] + 1}` to cause ambiguity ? Ok ... Maybe better phrased "a well defined effect" my definition of side was to restricted. Cheers Rolf ( addicted to the Perl Programming Language)	[reply] [d/l]

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