1 |
NAME |
2 |
Devel::FindRef - where is that reference to my scalar hiding? |
3 |
|
4 |
SYNOPSIS |
5 |
use Devel::FindRef; |
6 |
|
7 |
DESCRIPTION |
8 |
Tracking down reference problems (e.g. you expect some object to be |
9 |
destroyed, but there are still references to it that keep it alive). can |
10 |
be very hard, although perl keeps track of all values. |
11 |
|
12 |
The "track" function can hlep track down some of those refernces back to |
13 |
the variables containing them. |
14 |
|
15 |
For example, for this fragment: |
16 |
|
17 |
package Test; |
18 |
|
19 |
our $var = "hi\n"; |
20 |
my $x = \$var; |
21 |
our %hash = (ukukey => \$var); |
22 |
our $hash2 = {ukukey2 => \$var}; |
23 |
|
24 |
sub testsub { |
25 |
my $local = $hash2; |
26 |
print Devel::FindRef::track \$var; |
27 |
} |
28 |
|
29 |
testsub; |
30 |
|
31 |
The output is as follows (or similar to htis, in case I forget to update |
32 |
the manpage afetr some changes): |
33 |
|
34 |
SCALAR(0x676fa0) is |
35 |
referenced by REF(0x676fb0), which is |
36 |
in the lexical '$x' in CODE(0x676370), which is |
37 |
not found anywhere I looked :( |
38 |
referenced by REF(0x676360), which is |
39 |
in the member 'ukukey' of HASH(0x756660), which is |
40 |
in the global %Test::hash. |
41 |
in the global $Test::var. |
42 |
referenced by REF(0x6760e0), which is |
43 |
in the member 'ukukey2' of HASH(0x676f30), which is |
44 |
referenced by REF(0x77bcf0), which is |
45 |
in the lexical '$local' in CODE(0x77bcb0), which is |
46 |
in the global &Test::testsub. |
47 |
referenced by REF(0x77bc80), which is |
48 |
in the global $Test::hash2. |
49 |
|
50 |
It is a bit convoluted to read, but basically it says that the value |
51 |
stored in $var can be found: |
52 |
|
53 |
- in some variable $x whose origin is not known (I frankly have no idea |
54 |
why, hints accepted). |
55 |
- in the hash element with key "ukukey" in the hash stored in |
56 |
%Test::hash. |
57 |
- in the global variable named $Test::var. |
58 |
- in the hash element "ukukey2", in the hash in the my variable $local |
59 |
in the sub "Test::testsub" and also in the hash referenced by |
60 |
$Test::hash2. |
61 |
|
62 |
EXPORTS |
63 |
None. |
64 |
|
65 |
FUNCTIONS |
66 |
$string = Devel::FindRef::track $ref[, $depth] |
67 |
Track the perl value pointed to by $ref up to a depth of $depth |
68 |
and return a descriptive string. $ref can point at any perl |
69 |
value, be it anonymous sub, hash, array, scalar etc. |
70 |
|
71 |
This is the function you most often use. |
72 |
|
73 |
@references = Devel::FindRef::find $ref |
74 |
Return arrayrefs that contain [$message, $ref] pairs. The |
75 |
message describes what kind of reference was found and the $ref |
76 |
is the reference itself, which cna be omitted if "find" decided |
77 |
to end the search. |
78 |
|
79 |
The "track" function uses this to find references to the value |
80 |
you are interested in and recurses on the returned references. |
81 |
|
82 |
$ref = Devel::FindRef::ref2ptr $ptr |
83 |
Sometimes you know (from debugging output) the address of a perl |
84 |
scalar you are interested in. This function can be used to turn |
85 |
the address into a reference to that scalar. It is quite safe to |
86 |
call on valid addresses, but extremely dangerous to call on |
87 |
invalid ones. |
88 |
|
89 |
AUTHOR |
90 |
Marc Lehmann <pcg@goof.com>. |
91 |
|
92 |
BUGS |
93 |
Only code values, arrays, hashes, scalars and magic are being looked |
94 |
at. |
95 |
|
96 |
COPYRIGHT AND LICENSE |
97 |
Copyright (C) 2007 by Marc Lehmann. |
98 |
|
99 |
This library is free software; you can redistribute it and/or modify |
100 |
it under the same terms as Perl itself, either Perl version 5.8.8 |
101 |
or, at your option, any later version of Perl 5 you may have |
102 |
available. |
103 |
|