1 | """Generic (shallow and deep) copying operations. |
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2 | |
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3 | Interface summary: |
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4 | |
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5 | import copy |
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6 | |
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7 | x = copy.copy(y) # make a shallow copy of y |
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8 | x = copy.deepcopy(y) # make a deep copy of y |
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9 | |
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10 | For module specific errors, copy.Error is raised. |
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11 | |
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12 | The difference between shallow and deep copying is only relevant for |
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13 | compound objects (objects that contain other objects, like lists or |
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14 | class instances). |
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15 | |
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16 | - A shallow copy constructs a new compound object and then (to the |
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17 | extent possible) inserts *the same objects* into it that the |
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18 | original contains. |
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19 | |
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20 | - A deep copy constructs a new compound object and then, recursively, |
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21 | inserts *copies* into it of the objects found in the original. |
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22 | |
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23 | Two problems often exist with deep copy operations that don't exist |
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24 | with shallow copy operations: |
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25 | |
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26 | a) recursive objects (compound objects that, directly or indirectly, |
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27 | contain a reference to themselves) may cause a recursive loop |
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28 | |
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29 | b) because deep copy copies *everything* it may copy too much, e.g. |
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30 | administrative data structures that should be shared even between |
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31 | copies |
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32 | |
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33 | Python's deep copy operation avoids these problems by: |
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34 | |
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35 | a) keeping a table of objects already copied during the current |
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36 | copying pass |
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37 | |
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38 | b) letting user-defined classes override the copying operation or the |
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39 | set of components copied |
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40 | |
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41 | This version does not copy types like module, class, function, method, |
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42 | nor stack trace, stack frame, nor file, socket, window, nor array, nor |
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43 | any similar types. |
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44 | |
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45 | Classes can use the same interfaces to control copying that they use |
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46 | to control pickling: they can define methods called __getinitargs__(), |
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47 | __getstate__() and __setstate__(). See the documentation for module |
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48 | "pickle" for information on these methods. |
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49 | """ |
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50 | |
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51 | import types |
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52 | import weakref |
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53 | from copy_reg import dispatch_table |
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54 | |
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55 | class Error(Exception): |
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56 | pass |
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57 | error = Error # backward compatibility |
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58 | |
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59 | try: |
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60 | from org.python.core import PyStringMap |
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61 | except ImportError: |
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62 | PyStringMap = None |
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63 | |
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64 | __all__ = ["Error", "copy", "deepcopy"] |
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65 | |
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66 | def copy(x): |
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67 | """Shallow copy operation on arbitrary Python objects. |
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68 | |
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69 | See the module's __doc__ string for more info. |
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70 | """ |
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71 | |
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72 | cls = type(x) |
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73 | |
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74 | copier = _copy_dispatch.get(cls) |
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75 | if copier: |
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76 | return copier(x) |
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77 | |
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78 | copier = getattr(cls, "__copy__", None) |
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79 | if copier: |
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80 | return copier(x) |
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81 | |
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82 | reductor = dispatch_table.get(cls) |
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83 | if reductor: |
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84 | rv = reductor(x) |
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85 | else: |
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86 | reductor = getattr(x, "__reduce_ex__", None) |
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87 | if reductor: |
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88 | rv = reductor(2) |
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89 | else: |
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90 | reductor = getattr(x, "__reduce__", None) |
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91 | if reductor: |
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92 | rv = reductor() |
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93 | else: |
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94 | raise Error("un(shallow)copyable object of type %s" % cls) |
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95 | |
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96 | return _reconstruct(x, rv, 0) |
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97 | |
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98 | |
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99 | _copy_dispatch = d = {} |
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100 | |
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101 | def _copy_immutable(x): |
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102 | return x |
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103 | for t in (type(None), int, long, float, bool, str, tuple, |
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104 | frozenset, type, xrange, types.ClassType, |
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105 | types.BuiltinFunctionType, type(Ellipsis), |
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106 | types.FunctionType, weakref.ref): |
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107 | d[t] = _copy_immutable |
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108 | for name in ("ComplexType", "UnicodeType", "CodeType"): |
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109 | t = getattr(types, name, None) |
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110 | if t is not None: |
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111 | d[t] = _copy_immutable |
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112 | |
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113 | def _copy_with_constructor(x): |
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114 | return type(x)(x) |
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115 | for t in (list, dict, set): |
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116 | d[t] = _copy_with_constructor |
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117 | |
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118 | def _copy_with_copy_method(x): |
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119 | return x.copy() |
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120 | if PyStringMap is not None: |
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121 | d[PyStringMap] = _copy_with_copy_method |
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122 | |
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123 | def _copy_inst(x): |
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124 | if hasattr(x, '__copy__'): |
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125 | return x.__copy__() |
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126 | if hasattr(x, '__getinitargs__'): |
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127 | args = x.__getinitargs__() |
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128 | y = x.__class__(*args) |
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129 | else: |
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130 | y = _EmptyClass() |
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131 | y.__class__ = x.__class__ |
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132 | if hasattr(x, '__getstate__'): |
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133 | state = x.__getstate__() |
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134 | else: |
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135 | state = x.__dict__ |
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136 | if hasattr(y, '__setstate__'): |
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137 | y.__setstate__(state) |
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138 | else: |
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139 | y.__dict__.update(state) |
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140 | return y |
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141 | d[types.InstanceType] = _copy_inst |
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142 | |
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143 | del d |
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144 | |
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145 | def deepcopy(x, memo=None, _nil=[]): |
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146 | """Deep copy operation on arbitrary Python objects. |
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147 | |
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148 | See the module's __doc__ string for more info. |
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149 | """ |
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150 | |
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151 | if memo is None: |
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152 | memo = {} |
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153 | |
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154 | d = id(x) |
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155 | y = memo.get(d, _nil) |
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156 | if y is not _nil: |
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157 | return y |
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158 | |
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159 | cls = type(x) |
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160 | |
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161 | copier = _deepcopy_dispatch.get(cls) |
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162 | if copier: |
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163 | y = copier(x, memo) |
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164 | else: |
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165 | try: |
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166 | issc = issubclass(cls, type) |
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167 | except TypeError: # cls is not a class (old Boost; see SF #502085) |
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168 | issc = 0 |
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169 | if issc: |
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170 | y = _deepcopy_atomic(x, memo) |
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171 | else: |
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172 | copier = getattr(x, "__deepcopy__", None) |
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173 | if copier: |
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174 | y = copier(memo) |
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175 | else: |
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176 | reductor = dispatch_table.get(cls) |
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177 | if reductor: |
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178 | rv = reductor(x) |
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179 | else: |
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180 | reductor = getattr(x, "__reduce_ex__", None) |
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181 | if reductor: |
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182 | rv = reductor(2) |
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183 | else: |
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184 | reductor = getattr(x, "__reduce__", None) |
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185 | if reductor: |
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186 | rv = reductor() |
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187 | else: |
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188 | raise Error( |
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189 | "un(deep)copyable object of type %s" % cls) |
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190 | y = _reconstruct(x, rv, 1, memo) |
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191 | |
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192 | memo[d] = y |
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193 | _keep_alive(x, memo) # Make sure x lives at least as long as d |
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194 | return y |
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195 | |
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196 | _deepcopy_dispatch = d = {} |
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197 | |
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198 | def _deepcopy_atomic(x, memo): |
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199 | return x |
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200 | d[type(None)] = _deepcopy_atomic |
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201 | d[type(Ellipsis)] = _deepcopy_atomic |
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202 | d[int] = _deepcopy_atomic |
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203 | d[long] = _deepcopy_atomic |
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204 | d[float] = _deepcopy_atomic |
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205 | d[bool] = _deepcopy_atomic |
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206 | try: |
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207 | d[complex] = _deepcopy_atomic |
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208 | except NameError: |
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209 | pass |
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210 | d[str] = _deepcopy_atomic |
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211 | try: |
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212 | d[unicode] = _deepcopy_atomic |
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213 | except NameError: |
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214 | pass |
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215 | try: |
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216 | d[types.CodeType] = _deepcopy_atomic |
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217 | except AttributeError: |
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218 | pass |
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219 | d[type] = _deepcopy_atomic |
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220 | d[xrange] = _deepcopy_atomic |
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221 | d[types.ClassType] = _deepcopy_atomic |
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222 | d[types.BuiltinFunctionType] = _deepcopy_atomic |
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223 | d[types.FunctionType] = _deepcopy_atomic |
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224 | d[weakref.ref] = _deepcopy_atomic |
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225 | |
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226 | def _deepcopy_list(x, memo): |
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227 | y = [] |
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228 | memo[id(x)] = y |
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229 | for a in x: |
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230 | y.append(deepcopy(a, memo)) |
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231 | return y |
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232 | d[list] = _deepcopy_list |
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233 | |
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234 | def _deepcopy_tuple(x, memo): |
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235 | y = [] |
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236 | for a in x: |
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237 | y.append(deepcopy(a, memo)) |
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238 | d = id(x) |
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239 | try: |
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240 | return memo[d] |
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241 | except KeyError: |
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242 | pass |
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243 | for i in range(len(x)): |
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244 | if x[i] is not y[i]: |
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245 | y = tuple(y) |
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246 | break |
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247 | else: |
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248 | y = x |
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249 | memo[d] = y |
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250 | return y |
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251 | d[tuple] = _deepcopy_tuple |
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252 | |
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253 | def _deepcopy_dict(x, memo): |
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254 | y = {} |
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255 | memo[id(x)] = y |
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256 | for key, value in x.iteritems(): |
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257 | y[deepcopy(key, memo)] = deepcopy(value, memo) |
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258 | return y |
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259 | d[dict] = _deepcopy_dict |
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260 | if PyStringMap is not None: |
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261 | d[PyStringMap] = _deepcopy_dict |
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262 | |
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263 | def _deepcopy_method(x, memo): # Copy instance methods |
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264 | return type(x)(x.im_func, deepcopy(x.im_self, memo), x.im_class) |
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265 | _deepcopy_dispatch[types.MethodType] = _deepcopy_method |
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266 | |
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267 | def _keep_alive(x, memo): |
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268 | """Keeps a reference to the object x in the memo. |
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269 | |
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270 | Because we remember objects by their id, we have |
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271 | to assure that possibly temporary objects are kept |
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272 | alive by referencing them. |
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273 | We store a reference at the id of the memo, which should |
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274 | normally not be used unless someone tries to deepcopy |
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275 | the memo itself... |
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276 | """ |
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277 | try: |
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278 | memo[id(memo)].append(x) |
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279 | except KeyError: |
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280 | # aha, this is the first one :-) |
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281 | memo[id(memo)]=[x] |
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282 | |
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283 | def _deepcopy_inst(x, memo): |
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284 | if hasattr(x, '__deepcopy__'): |
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285 | return x.__deepcopy__(memo) |
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286 | if hasattr(x, '__getinitargs__'): |
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287 | args = x.__getinitargs__() |
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288 | args = deepcopy(args, memo) |
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289 | y = x.__class__(*args) |
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290 | else: |
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291 | y = _EmptyClass() |
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292 | y.__class__ = x.__class__ |
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293 | memo[id(x)] = y |
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294 | if hasattr(x, '__getstate__'): |
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295 | state = x.__getstate__() |
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296 | else: |
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297 | state = x.__dict__ |
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298 | state = deepcopy(state, memo) |
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299 | if hasattr(y, '__setstate__'): |
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300 | y.__setstate__(state) |
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301 | else: |
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302 | y.__dict__.update(state) |
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303 | return y |
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304 | d[types.InstanceType] = _deepcopy_inst |
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305 | |
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306 | def _reconstruct(x, info, deep, memo=None): |
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307 | if isinstance(info, str): |
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308 | return x |
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309 | assert isinstance(info, tuple) |
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310 | if memo is None: |
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311 | memo = {} |
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312 | n = len(info) |
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313 | assert n in (2, 3, 4, 5) |
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314 | callable, args = info[:2] |
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315 | if n > 2: |
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316 | state = info[2] |
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317 | else: |
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318 | state = None |
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319 | if n > 3: |
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320 | listiter = info[3] |
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321 | else: |
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322 | listiter = None |
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323 | if n > 4: |
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324 | dictiter = info[4] |
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325 | else: |
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326 | dictiter = None |
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327 | if deep: |
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328 | args = deepcopy(args, memo) |
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329 | y = callable(*args) |
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330 | memo[id(x)] = y |
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331 | |
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332 | if state is not None: |
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333 | if deep: |
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334 | state = deepcopy(state, memo) |
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335 | if hasattr(y, '__setstate__'): |
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336 | y.__setstate__(state) |
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337 | else: |
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338 | if isinstance(state, tuple) and len(state) == 2: |
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339 | state, slotstate = state |
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340 | else: |
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341 | slotstate = None |
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342 | if state is not None: |
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343 | y.__dict__.update(state) |
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344 | if slotstate is not None: |
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345 | for key, value in slotstate.iteritems(): |
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346 | setattr(y, key, value) |
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347 | |
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348 | if listiter is not None: |
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349 | for item in listiter: |
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350 | if deep: |
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351 | item = deepcopy(item, memo) |
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352 | y.append(item) |
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353 | if dictiter is not None: |
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354 | for key, value in dictiter: |
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355 | if deep: |
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356 | key = deepcopy(key, memo) |
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357 | value = deepcopy(value, memo) |
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358 | y[key] = value |
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359 | return y |
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360 | |
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361 | del d |
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362 | |
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363 | del types |
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364 | |
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365 | # Helper for instance creation without calling __init__ |
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366 | class _EmptyClass: |
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367 | pass |
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368 | |
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369 | def _test(): |
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370 | l = [None, 1, 2L, 3.14, 'xyzzy', (1, 2L), [3.14, 'abc'], |
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371 | {'abc': 'ABC'}, (), [], {}] |
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372 | l1 = copy(l) |
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373 | print l1==l |
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374 | l1 = map(copy, l) |
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375 | print l1==l |
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376 | l1 = deepcopy(l) |
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377 | print l1==l |
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378 | class C: |
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379 | def __init__(self, arg=None): |
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380 | self.a = 1 |
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381 | self.arg = arg |
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382 | if __name__ == '__main__': |
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383 | import sys |
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384 | file = sys.argv[0] |
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385 | else: |
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386 | file = __file__ |
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387 | self.fp = open(file) |
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388 | self.fp.close() |
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389 | def __getstate__(self): |
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390 | return {'a': self.a, 'arg': self.arg} |
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391 | def __setstate__(self, state): |
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392 | for key, value in state.iteritems(): |
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393 | setattr(self, key, value) |
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394 | def __deepcopy__(self, memo=None): |
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395 | new = self.__class__(deepcopy(self.arg, memo)) |
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396 | new.a = self.a |
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397 | return new |
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398 | c = C('argument sketch') |
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399 | l.append(c) |
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400 | l2 = copy(l) |
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401 | print l == l2 |
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402 | print l |
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403 | print l2 |
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404 | l2 = deepcopy(l) |
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405 | print l == l2 |
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406 | print l |
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407 | print l2 |
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408 | l.append({l[1]: l, 'xyz': l[2]}) |
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409 | l3 = copy(l) |
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410 | import repr |
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411 | print map(repr.repr, l) |
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412 | print map(repr.repr, l1) |
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413 | print map(repr.repr, l2) |
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414 | print map(repr.repr, l3) |
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415 | l3 = deepcopy(l) |
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416 | import repr |
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417 | print map(repr.repr, l) |
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418 | print map(repr.repr, l1) |
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419 | print map(repr.repr, l2) |
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420 | print map(repr.repr, l3) |
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421 | class odict(dict): |
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422 | def __init__(self, d = {}): |
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423 | self.a = 99 |
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424 | dict.__init__(self, d) |
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425 | def __setitem__(self, k, i): |
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426 | dict.__setitem__(self, k, i) |
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427 | self.a |
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428 | o = odict({"A" : "B"}) |
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429 | x = deepcopy(o) |
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430 | print(o, x) |
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431 | |
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432 | if __name__ == '__main__': |
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433 | _test() |
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