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