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Array-Referenzen werden zu Hashreferenzen
DB<50> @arr=(0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15)
DB<69> x \{@arr}
0 SCALAR(0x91a4a94)
-> HASH(0x91a198c)
0 => 1
10 => 11
12 => 13
14 => 15
2 => 3
4 => 5
6 => 7
8 => 9
DB<70> x \@arr # this way it works as expected
0 ARRAY(0x919d7e4)
0 0
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
10 10
11 11
12 12
13 13
14 14
15 15
DB<71> x {@arr}
DB<66> $cpy= \{@arr[10..12]}
DB<67> x $cpy
0 SCALAR(0x91a29cc)
-> HASH(0x91a2b70)
10 => 11
12 => undef
DB<68> x $cpy->[0]
Not an ARRAY reference at (eval 89)[/usr/local/lib/perl5/5.6.0/perl5db.pl:1510] line 2, <IN> line 72.
How are slices implemented? Full-blown arrays created as (shallow)
copies of the specified section of the original array, or just a
pointer to the original array, plus two indizes?
DB<75> $deepobj=[30,40,50,60]
DB<76>
main::(./tv_gui_regrtest.pl:61): print "ALL TESTS SUCCESFUL.\n";
DB<76>
ALL TESTS SUCCESFUL.
Debugged program terminated. Use q to quit or R to restart,
use O inhibit_exit to avoid stopping after program termination,
h q, h R or h O to get additional info.
DB<76> x $deepobj
0 ARRAY(0x91a6bac)
0 30
1 40
2 50
3 60
DB<77> push @arr, $deepobj
DB<78> push @arr, 42
DB<79> push @arr, 43
DB<80> x @arr
0 0
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 ARRAY(0x91a6bac)
0 30
1 40
2 50
3 60
17 42
18 43
DB<82> x @cpy2=@arr[13..17]
0 13
1 14
2 15
3 ARRAY(0x91a6bac)
0 30
1 40
2 50
3 60
4 42
DB<83> x push @$cpy2[2],70
Type of arg 1 to push must be array (not array slice) at (eval 104)[/usr/local/lib/perl5/5.6.0/perl5db.pl:1510] line 2, at EOF
DB<84> x push @{$cpy2[2]},70
0 1
DB<85> x @cpy2
0 13
1 14
2 15
3 ARRAY(0x91a6bac)
0 30
1 40
2 50
3 60
4 42
DB<86> x push @{$cpy2[3]},70
0 5
DB<87> x @cpy2
0 13
1 14
2 15
3 ARRAY(0x91a6bac)
0 30
1 40
2 50
3 60
4 70
4 42
DB<88> x @arr
0 0
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 ARRAY(0x91a6bac)
0 30
1 40
2 50
3 60
4 70
17 42
18 43
DB<89>
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Apparently "iterators" over arrays as established by e.g. "foreach"
are not part of the array itself:
DB<89> @arr2=(0,1,2)
DB<91> for $it1 (@arr2) { for $it2 (@arr2) { print "$it1 $it2 "; }}
0 0 0 1 0 2 1 0 1 1 1 2 2 0 2 1 2 2
Is there a way to create and increment such iterators manually, or are
they an integrated part of the "foreach" magic?
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how do you obtain a reference to a hash returned by a function call?
e.g.:
this gives me the hash returned by "map":
DB<126> x map { ($_=>1) } 6,8,3,4,2
0 6
1 1
2 8
3 1
4 3
5 1
6 4
7 1
8 2
9 1
same here (why doesn't this create a reference to the hash?)
DB<127> x { map { ($_=>1) } 6,8,3,4,2 }
0 6
1 1
2 8
3 1
4 3
5 1
6 4
7 1
8 2
9 1
but this gives me a reference to a reference to the hash!
DB<128> x \{ map { ($_=>1) } 6,8,3,4,2 }
0 REF(0x84dfb90)
-> HASH(0x84dc22c)
2 => 1
3 => 1
4 => 1
6 => 1
8 => 1
And this doesn't work either:
DB<129> x \ map { ($_=>1) } 6,8,3,4,2
0 SCALAR(0x84e0a98)
-> 6
1 SCALAR(0x84dc250)
-> 1
2 SCALAR(0x84e4254)
-> 8
3 SCALAR(0x84de0cc)
-> 1
4 SCALAR(0x84e0b64)
-> 3
5 SCALAR(0x84e0d7c)
-> 1
6 SCALAR(0x84e0a74)
-> 4
7 SCALAR(0x84e4278)
-> 1
8 SCALAR(0x84dc004)
-> 2
9 SCALAR(0x84de1a4)
-> 1
DB<130>
it only works as expected when I create a temporary variable:
DB<130> x %res=map { ($_=>1) } 6,8,3,4,2; \%res
0 HASH(0x84e0c54)
2 => 1
3 => 1
4 => 1
6 => 1
8 => 1
DB<131>
aaaah...
DB<141> x +{ map {$_+3} 6,8,3,4,2,5 }
0 HASH(0x84e0cb4)
5 => 8
6 => 7
9 => 11
DB<142>
(see "man perlref"/"making references"/3.)
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