Larry Wall wrote: >Whatever the answer, it probably has to apply to > > my @a; > @a[0] = '1'; > @a[2] = '3'; > print exists $a[1]; > >as well as the explicit delete case. Are we going to pitch an exception for >writing beyond the end of an array? That seems a bit anti-Perlish. > >
What's the semantic difference between "exists but is undefined" and "does not exist"? IOW: my @a = (1,2,3); @a[1] = undef; print exists @a[1]; print @a[1]; versus: my @a = (1,2,3); delete @a[1]; print exists @a[1]; print @a[1]; If I try to store @a[1], it auto(re)vivifies, right? If I fetch @a[1], do I get an exception or just an undef? To force undef, do I use "err" or "//"? my $a1 = @a[1] err undef; my $a1 = @a[1] // undef; Does @a.k return different results? (0..2) vs (0,2) >: * how do you store nonexistence for native packed arrays > > > We've beaten this horse, or one that looks vanishingly like it, a bunch of times. 1. Implementation issue. Throw it to p6i. 2. For infrequent exceptions, create an exception-list. 3. For frequent exceptions, create a bitmap. 4. For exceptions in unbalanced data, create an escape value. >: Anyway, I want this behavior to die. Maybe we should get rid of >: .delete() on arrays, or maybe we should equate it with >: .splice($idx,1). > >Or maybe we support sparse arrays as one container type. > > Sure, but what's the default behavior? If I consume the endpoints of an array, using shift or pop, how is that different from consuming the middle? my @a = (1,2,3); shift @a; shift @a; print @a.indexof(3); # 0 or 2? Based on that, I'll argue that the default array mode is "contains a list," which means that array contents should act like lists. Delete something in the middle, and you have a shorter list, not a list with a hole in it. Harrays and Arrashes can be different types, or maybe can just be properties of the basic sigillated types. my @a = (1,2,3) is arrash; # sparse my %h = (1 => 'a', 2 => 'b') is harray; >I actually used a crowbar last week. It wasn't pretty, but it got >the job done. Well, okay, it got the job started...I still have a >hole in my living room wall, but my chief interest at the time was >to make sure my house wasn't going to burn down. That's about as >much abstraction as you could wish for in real life. > > Dude, you're scaring me. Should there be a license required for home ownership? =Austin
