node_modules/websocket/node_modules/nan/doc/maybe_types.md

   1 ## Maybe Types
   2
   3 The `Nan::MaybeLocal` and `Nan::Maybe` types are monads that encapsulate `v8::Local` handles that _may be empty_.
   4
   5 * **Maybe Types**
   6   - <a href="#api_nan_maybe_local"><b><code>Nan::MaybeLocal</code></b></a>
   7   - <a href="#api_nan_maybe"><b><code>Nan::Maybe</code></b></a>
   8   - <a href="#api_nan_nothing"><b><code>Nan::Nothing</code></b></a>
   9   - <a href="#api_nan_just"><b><code>Nan::Just</code></b></a>
  10 * **Maybe Helpers**
  11   - <a href="#api_nan_call"><b><code>Nan::Call()</code></b></a>
  12   - <a href="#api_nan_to_detail_string"><b><code>Nan::ToDetailString()</code></b></a>
  13   - <a href="#api_nan_to_array_index"><b><code>Nan::ToArrayIndex()</code></b></a>
  14   - <a href="#api_nan_equals"><b><code>Nan::Equals()</code></b></a>
  15   - <a href="#api_nan_new_instance"><b><code>Nan::NewInstance()</code></b></a>
  16   - <a href="#api_nan_get_function"><b><code>Nan::GetFunction()</code></b></a>
  17   - <a href="#api_nan_set"><b><code>Nan::Set()</code></b></a>
  18   - <a href="#api_nan_define_own_property"><b><code>Nan::DefineOwnProperty()</code></b></a>
  19   - <a href="#api_nan_force_set"><del><b><code>Nan::ForceSet()</code></b></del></a>
  20   - <a href="#api_nan_get"><b><code>Nan::Get()</code></b></a>
  21   - <a href="#api_nan_get_property_attribute"><b><code>Nan::GetPropertyAttributes()</code></b></a>
  22   - <a href="#api_nan_has"><b><code>Nan::Has()</code></b></a>
  23   - <a href="#api_nan_delete"><b><code>Nan::Delete()</code></b></a>
  24   - <a href="#api_nan_get_property_names"><b><code>Nan::GetPropertyNames()</code></b></a>
  25   - <a href="#api_nan_get_own_property_names"><b><code>Nan::GetOwnPropertyNames()</code></b></a>
  26   - <a href="#api_nan_set_prototype"><b><code>Nan::SetPrototype()</code></b></a>
  27   - <a href="#api_nan_object_proto_to_string"><b><code>Nan::ObjectProtoToString()</code></b></a>
  28   - <a href="#api_nan_has_own_property"><b><code>Nan::HasOwnProperty()</code></b></a>
  29   - <a href="#api_nan_has_real_named_property"><b><code>Nan::HasRealNamedProperty()</code></b></a>
  30   - <a href="#api_nan_has_real_indexed_property"><b><code>Nan::HasRealIndexedProperty()</code></b></a>
  31   - <a href="#api_nan_has_real_named_callback_property"><b><code>Nan::HasRealNamedCallbackProperty()</code></b></a>
  32   - <a href="#api_nan_get_real_named_property_in_prototype_chain"><b><code>Nan::GetRealNamedPropertyInPrototypeChain()</code></b></a>
  33   - <a href="#api_nan_get_real_named_property"><b><code>Nan::GetRealNamedProperty()</code></b></a>
  34   - <a href="#api_nan_call_as_function"><b><code>Nan::CallAsFunction()</code></b></a>
  35   - <a href="#api_nan_call_as_constructor"><b><code>Nan::CallAsConstructor()</code></b></a>
  36   - <a href="#api_nan_get_source_line"><b><code>Nan::GetSourceLine()</code></b></a>
  37   - <a href="#api_nan_get_line_number"><b><code>Nan::GetLineNumber()</code></b></a>
  38   - <a href="#api_nan_get_start_column"><b><code>Nan::GetStartColumn()</code></b></a>
  39   - <a href="#api_nan_get_end_column"><b><code>Nan::GetEndColumn()</code></b></a>
  40   - <a href="#api_nan_clone_element_at"><b><code>Nan::CloneElementAt()</code></b></a>
  41   - <a href="#api_nan_has_private"><b><code>Nan::HasPrivate()</code></b></a>
  42   - <a href="#api_nan_get_private"><b><code>Nan::GetPrivate()</code></b></a>
  43   - <a href="#api_nan_set_private"><b><code>Nan::SetPrivate()</code></b></a>
  44   - <a href="#api_nan_delete_private"><b><code>Nan::DeletePrivate()</code></b></a>
  45   - <a href="#api_nan_make_maybe"><b><code>Nan::MakeMaybe()</code></b></a>
  46
  47 <a name="api_nan_maybe_local"></a>
  48 ### Nan::MaybeLocal
  49
  50 A `Nan::MaybeLocal<T>` is a wrapper around [`v8::Local<T>`](https://v8docs.nodesource.com/node-8.11/de/deb/classv8_1_1_local.html) that enforces a check that determines whether the `v8::Local<T>` is empty before it can be used.
  51
  52 If an API method returns a `Nan::MaybeLocal`, the API method can potentially fail either because an exception is thrown, or because an exception is pending, e.g. because a previous API call threw an exception that hasn't been caught yet, or because a `v8::TerminateExecution` exception was thrown. In that case, an empty `Nan::MaybeLocal` is returned.
  53
  54 Definition:
  55
  56 ```c++
  57 template<typename T> class Nan::MaybeLocal {
  58  public:
  59   MaybeLocal();
  60
  61   template<typename S> MaybeLocal(v8::Local<S> that);
  62
  63   bool IsEmpty() const;
  64
  65   template<typename S> bool ToLocal(v8::Local<S> *out);
  66
  67   // Will crash if the MaybeLocal<> is empty.
  68   v8::Local<T> ToLocalChecked();
  69
  70   template<typename S> v8::Local<S> FromMaybe(v8::Local<S> default_value) const;
  71 };
  72 ```
  73
  74 See the documentation for [`v8::MaybeLocal`](https://v8docs.nodesource.com/node-8.11/d8/d7d/classv8_1_1_maybe_local.html) for further details.
  75
  76 <a name="api_nan_maybe"></a>
  77 ### Nan::Maybe
  78
  79 A simple `Nan::Maybe` type, representing an object which may or may not have a value, see https://hackage.haskell.org/package/base/docs/Data-Maybe.html.
  80
  81 If an API method returns a `Nan::Maybe<>`, the API method can potentially fail either because an exception is thrown, or because an exception is pending, e.g. because a previous API call threw an exception that hasn't been caught yet, or because a `v8::TerminateExecution` exception was thrown. In that case, a "Nothing" value is returned.
  82
  83 Definition:
  84
  85 ```c++
  86 template<typename T> class Nan::Maybe {
  87  public:
  88   bool IsNothing() const;
  89   bool IsJust() const;
  90
  91   // Will crash if the Maybe<> is nothing.
  92   T FromJust();
  93
  94   T FromMaybe(const T& default_value);
  95
  96   bool operator==(const Maybe &other);
  97
  98   bool operator!=(const Maybe &other);
  99 };
 100 ```
 101
 102 See the documentation for [`v8::Maybe`](https://v8docs.nodesource.com/node-8.11/d9/d4b/classv8_1_1_maybe.html) for further details.
 103
 104 <a name="api_nan_nothing"></a>
 105 ### Nan::Nothing
 106
 107 Construct an empty `Nan::Maybe` type representing _nothing_.
 108
 109 ```c++
 110 template<typename T> Nan::Maybe<T> Nan::Nothing();
 111 ```
 112
 113 <a name="api_nan_just"></a>
 114 ### Nan::Just
 115
 116 Construct a `Nan::Maybe` type representing _just_ a value.
 117
 118 ```c++
 119 template<typename T> Nan::Maybe<T> Nan::Just(const T &t);
 120 ```
 121
 122 <a name="api_nan_call"></a>
 123 ### Nan::Call()
 124
 125 A helper method for calling a synchronous [`v8::Function#Call()`](https://v8docs.nodesource.com/node-8.11/d5/d54/classv8_1_1_function.html#a9c3d0e4e13ddd7721fce238aa5b94a11) in a way compatible across supported versions of V8.
 126
 127 For asynchronous callbacks, use Nan::Callback::Call along with an AsyncResource.
 128
 129 Signature:
 130
 131 ```c++
 132 Nan::MaybeLocal<v8::Value> Nan::Call(v8::Local<v8::Function> fun, v8::Local<v8::Object> recv, int argc, v8::Local<v8::Value> argv[]);
 133 Nan::MaybeLocal<v8::Value> Nan::Call(const Nan::Callback& callback, v8::Local<v8::Object> recv,
 134  int argc, v8::Local<v8::Value> argv[]);
 135 Nan::MaybeLocal<v8::Value> Nan::Call(const Nan::Callback& callback, int argc, v8::Local<v8::Value> argv[]);
 136 ```
 137
 138
 139 <a name="api_nan_to_detail_string"></a>
 140 ### Nan::ToDetailString()
 141
 142 A helper method for calling [`v8::Value#ToDetailString()`](https://v8docs.nodesource.com/node-8.11/dc/d0a/classv8_1_1_value.html#a2f9770296dc2c8d274bc8cc0dca243e5) in a way compatible across supported versions of V8.
 143
 144 Signature:
 145
 146 ```c++
 147 Nan::MaybeLocal<v8::String> Nan::ToDetailString(v8::Local<v8::Value> val);
 148 ```
 149
 150
 151 <a name="api_nan_to_array_index"></a>
 152 ### Nan::ToArrayIndex()
 153
 154 A helper method for calling [`v8::Value#ToArrayIndex()`](https://v8docs.nodesource.com/node-8.11/dc/d0a/classv8_1_1_value.html#acc5bbef3c805ec458470c0fcd6f13493) in a way compatible across supported versions of V8.
 155
 156 Signature:
 157
 158 ```c++
 159 Nan::MaybeLocal<v8::Uint32> Nan::ToArrayIndex(v8::Local<v8::Value> val);
 160 ```
 161
 162
 163 <a name="api_nan_equals"></a>
 164 ### Nan::Equals()
 165
 166 A helper method for calling [`v8::Value#Equals()`](https://v8docs.nodesource.com/node-8.11/dc/d0a/classv8_1_1_value.html#a08fba1d776a59bbf6864b25f9152c64b) in a way compatible across supported versions of V8.
 167
 168 Signature:
 169
 170 ```c++
 171 Nan::Maybe<bool> Nan::Equals(v8::Local<v8::Value> a, v8::Local<v8::Value>(b));
 172 ```
 173
 174
 175 <a name="api_nan_new_instance"></a>
 176 ### Nan::NewInstance()
 177
 178 A helper method for calling [`v8::Function#NewInstance()`](https://v8docs.nodesource.com/node-8.11/d5/d54/classv8_1_1_function.html#ae477558b10c14b76ed00e8dbab44ce5b) and [`v8::ObjectTemplate#NewInstance()`](https://v8docs.nodesource.com/node-8.11/db/d5f/classv8_1_1_object_template.html#ad605a7543cfbc5dab54cdb0883d14ae4) in a way compatible across supported versions of V8.
 179
 180 Signature:
 181
 182 ```c++
 183 Nan::MaybeLocal<v8::Object> Nan::NewInstance(v8::Local<v8::Function> h);
 184 Nan::MaybeLocal<v8::Object> Nan::NewInstance(v8::Local<v8::Function> h, int argc, v8::Local<v8::Value> argv[]);
 185 Nan::MaybeLocal<v8::Object> Nan::NewInstance(v8::Local<v8::ObjectTemplate> h);
 186 ```
 187
 188
 189 <a name="api_nan_get_function"></a>
 190 ### Nan::GetFunction()
 191
 192 A helper method for calling [`v8::FunctionTemplate#GetFunction()`](https://v8docs.nodesource.com/node-8.11/d8/d83/classv8_1_1_function_template.html#a56d904662a86eca78da37d9bb0ed3705) in a way compatible across supported versions of V8.
 193
 194 Signature:
 195
 196 ```c++
 197 Nan::MaybeLocal<v8::Function> Nan::GetFunction(v8::Local<v8::FunctionTemplate> t);
 198 ```
 199
 200
 201 <a name="api_nan_set"></a>
 202 ### Nan::Set()
 203
 204 A helper method for calling [`v8::Object#Set()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a67604ea3734f170c66026064ea808f20) in a way compatible across supported versions of V8.
 205
 206 Signature:
 207
 208 ```c++
 209 Nan::Maybe<bool> Nan::Set(v8::Local<v8::Object> obj,
 210                           v8::Local<v8::Value> key,
 211                           v8::Local<v8::Value> value)
 212 Nan::Maybe<bool> Nan::Set(v8::Local<v8::Object> obj,
 213                           uint32_t index,
 214                           v8::Local<v8::Value> value);
 215 ```
 216
 217
 218 <a name="api_nan_define_own_property"></a>
 219 ### Nan::DefineOwnProperty()
 220
 221 A helper method for calling [`v8::Object#DefineOwnProperty()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a6f76b2ed605cb8f9185b92de0033a820) in a way compatible across supported versions of V8.
 222
 223 Signature:
 224
 225 ```c++
 226 Nan::Maybe<bool> Nan::DefineOwnProperty(v8::Local<v8::Object> obj,
 227                                         v8::Local<v8::String> key,
 228                                         v8::Local<v8::Value> value,
 229                                         v8::PropertyAttribute attribs = v8::None);
 230 ```
 231
 232
 233 <a name="api_nan_force_set"></a>
 234 ### <del>Nan::ForceSet()</del>
 235
 236 Deprecated, use <a href="#api_nan_define_own_property"><code>Nan::DefineOwnProperty()</code></a>.
 237
 238 <del>A helper method for calling [`v8::Object#ForceSet()`](https://v8docs.nodesource.com/node-0.12/db/d85/classv8_1_1_object.html#acfbdfd7427b516ebdb5c47c4df5ed96c) in a way compatible across supported versions of V8.</del>
 239
 240 Signature:
 241
 242 ```c++
 243 NAN_DEPRECATED Nan::Maybe<bool> Nan::ForceSet(v8::Local<v8::Object> obj,
 244                                               v8::Local<v8::Value> key,
 245                                               v8::Local<v8::Value> value,
 246                                               v8::PropertyAttribute attribs = v8::None);
 247 ```
 248
 249
 250 <a name="api_nan_get"></a>
 251 ### Nan::Get()
 252
 253 A helper method for calling [`v8::Object#Get()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a2565f03e736694f6b1e1cf22a0b4eac2) in a way compatible across supported versions of V8.
 254
 255 Signature:
 256
 257 ```c++
 258 Nan::MaybeLocal<v8::Value> Nan::Get(v8::Local<v8::Object> obj,
 259                                     v8::Local<v8::Value> key);
 260 Nan::MaybeLocal<v8::Value> Nan::Get(v8::Local<v8::Object> obj, uint32_t index);
 261 ```
 262
 263
 264 <a name="api_nan_get_property_attribute"></a>
 265 ### Nan::GetPropertyAttributes()
 266
 267 A helper method for calling [`v8::Object#GetPropertyAttributes()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a9b898894da3d1db2714fd9325a54fe57) in a way compatible across supported versions of V8.
 268
 269 Signature:
 270
 271 ```c++
 272 Nan::Maybe<v8::PropertyAttribute> Nan::GetPropertyAttributes(
 273     v8::Local<v8::Object> obj,
 274     v8::Local<v8::Value> key);
 275 ```
 276
 277
 278 <a name="api_nan_has"></a>
 279 ### Nan::Has()
 280
 281 A helper method for calling [`v8::Object#Has()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#ab3c3d89ea7c2f9afd08965bd7299a41d) in a way compatible across supported versions of V8.
 282
 283 Signature:
 284
 285 ```c++
 286 Nan::Maybe<bool> Nan::Has(v8::Local<v8::Object> obj, v8::Local<v8::String> key);
 287 Nan::Maybe<bool> Nan::Has(v8::Local<v8::Object> obj, uint32_t index);
 288 ```
 289
 290
 291 <a name="api_nan_delete"></a>
 292 ### Nan::Delete()
 293
 294 A helper method for calling [`v8::Object#Delete()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a48e4a19b2cedff867eecc73ddb7d377f) in a way compatible across supported versions of V8.
 295
 296 Signature:
 297
 298 ```c++
 299 Nan::Maybe<bool> Nan::Delete(v8::Local<v8::Object> obj,
 300                              v8::Local<v8::String> key);
 301 Nan::Maybe<bool> Nan::Delete(v8::Local<v8::Object> obj, uint32_t index);
 302 ```
 303
 304
 305 <a name="api_nan_get_property_names"></a>
 306 ### Nan::GetPropertyNames()
 307
 308 A helper method for calling [`v8::Object#GetPropertyNames()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#aced885270cfd2c956367b5eedc7fbfe8) in a way compatible across supported versions of V8.
 309
 310 Signature:
 311
 312 ```c++
 313 Nan::MaybeLocal<v8::Array> Nan::GetPropertyNames(v8::Local<v8::Object> obj);
 314 ```
 315
 316
 317 <a name="api_nan_get_own_property_names"></a>
 318 ### Nan::GetOwnPropertyNames()
 319
 320 A helper method for calling [`v8::Object#GetOwnPropertyNames()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a79a6e4d66049b9aa648ed4dfdb23e6eb) in a way compatible across supported versions of V8.
 321
 322 Signature:
 323
 324 ```c++
 325 Nan::MaybeLocal<v8::Array> Nan::GetOwnPropertyNames(v8::Local<v8::Object> obj);
 326 ```
 327
 328
 329 <a name="api_nan_set_prototype"></a>
 330 ### Nan::SetPrototype()
 331
 332 A helper method for calling [`v8::Object#SetPrototype()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a442706b22fceda6e6d1f632122a9a9f4) in a way compatible across supported versions of V8.
 333
 334 Signature:
 335
 336 ```c++
 337 Nan::Maybe<bool> Nan::SetPrototype(v8::Local<v8::Object> obj,
 338                                    v8::Local<v8::Value> prototype);
 339 ```
 340
 341
 342 <a name="api_nan_object_proto_to_string"></a>
 343 ### Nan::ObjectProtoToString()
 344
 345 A helper method for calling [`v8::Object#ObjectProtoToString()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#ab7a92b4dcf822bef72f6c0ac6fea1f0b) in a way compatible across supported versions of V8.
 346
 347 Signature:
 348
 349 ```c++
 350 Nan::MaybeLocal<v8::String> Nan::ObjectProtoToString(v8::Local<v8::Object> obj);
 351 ```
 352
 353
 354 <a name="api_nan_has_own_property"></a>
 355 ### Nan::HasOwnProperty()
 356
 357 A helper method for calling [`v8::Object#HasOwnProperty()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#ab7b7245442ca6de1e1c145ea3fd653ff) in a way compatible across supported versions of V8.
 358
 359 Signature:
 360
 361 ```c++
 362 Nan::Maybe<bool> Nan::HasOwnProperty(v8::Local<v8::Object> obj,
 363                                      v8::Local<v8::String> key);
 364 ```
 365
 366
 367 <a name="api_nan_has_real_named_property"></a>
 368 ### Nan::HasRealNamedProperty()
 369
 370 A helper method for calling [`v8::Object#HasRealNamedProperty()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#ad8b80a59c9eb3c1e6c3cd6c84571f767) in a way compatible across supported versions of V8.
 371
 372 Signature:
 373
 374 ```c++
 375 Nan::Maybe<bool> Nan::HasRealNamedProperty(v8::Local<v8::Object> obj,
 376                                            v8::Local<v8::String> key);
 377 ```
 378
 379
 380 <a name="api_nan_has_real_indexed_property"></a>
 381 ### Nan::HasRealIndexedProperty()
 382
 383 A helper method for calling [`v8::Object#HasRealIndexedProperty()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#af94fc1135a5e74a2193fb72c3a1b9855) in a way compatible across supported versions of V8.
 384
 385 Signature:
 386
 387 ```c++
 388 Nan::Maybe<bool> Nan::HasRealIndexedProperty(v8::Local<v8::Object> obj,
 389                                              uint32_t index);
 390 ```
 391
 392
 393 <a name="api_nan_has_real_named_callback_property"></a>
 394 ### Nan::HasRealNamedCallbackProperty()
 395
 396 A helper method for calling [`v8::Object#HasRealNamedCallbackProperty()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#af743b7ea132b89f84d34d164d0668811) in a way compatible across supported versions of V8.
 397
 398 Signature:
 399
 400 ```c++
 401 Nan::Maybe<bool> Nan::HasRealNamedCallbackProperty(
 402     v8::Local<v8::Object> obj,
 403     v8::Local<v8::String> key);
 404 ```
 405
 406
 407 <a name="api_nan_get_real_named_property_in_prototype_chain"></a>
 408 ### Nan::GetRealNamedPropertyInPrototypeChain()
 409
 410 A helper method for calling [`v8::Object#GetRealNamedPropertyInPrototypeChain()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a8700b1862e6b4783716964ba4d5e6172) in a way compatible across supported versions of V8.
 411
 412 Signature:
 413
 414 ```c++
 415 Nan::MaybeLocal<v8::Value> Nan::GetRealNamedPropertyInPrototypeChain(
 416     v8::Local<v8::Object> obj,
 417     v8::Local<v8::String> key);
 418 ```
 419
 420
 421 <a name="api_nan_get_real_named_property"></a>
 422 ### Nan::GetRealNamedProperty()
 423
 424 A helper method for calling [`v8::Object#GetRealNamedProperty()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a84471a824576a5994fdd0ffcbf99ccc0) in a way compatible across supported versions of V8.
 425
 426 Signature:
 427
 428 ```c++
 429 Nan::MaybeLocal<v8::Value> Nan::GetRealNamedProperty(v8::Local<v8::Object> obj,
 430                                                      v8::Local<v8::String> key);
 431 ```
 432
 433
 434 <a name="api_nan_call_as_function"></a>
 435 ### Nan::CallAsFunction()
 436
 437 A helper method for calling [`v8::Object#CallAsFunction()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#ad3ffc36f3dfc3592ce2a96bc047ee2cd) in a way compatible across supported versions of V8.
 438
 439 Signature:
 440
 441 ```c++
 442 Nan::MaybeLocal<v8::Value> Nan::CallAsFunction(v8::Local<v8::Object> obj,
 443                                                v8::Local<v8::Object> recv,
 444                                                int argc,
 445                                                v8::Local<v8::Value> argv[]);
 446 ```
 447
 448
 449 <a name="api_nan_call_as_constructor"></a>
 450 ### Nan::CallAsConstructor()
 451
 452 A helper method for calling [`v8::Object#CallAsConstructor()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a50d571de50d0b0dfb28795619d07a01b) in a way compatible across supported versions of V8.
 453
 454 Signature:
 455
 456 ```c++
 457 Nan::MaybeLocal<v8::Value> Nan::CallAsConstructor(v8::Local<v8::Object> obj,
 458                                                   int argc,
 459                                                   v8::Local<v8::Value> argv[]);
 460 ```
 461
 462
 463 <a name="api_nan_get_source_line"></a>
 464 ### Nan::GetSourceLine()
 465
 466 A helper method for calling [`v8::Message#GetSourceLine()`](https://v8docs.nodesource.com/node-8.11/d9/d28/classv8_1_1_message.html#a849f7a6c41549d83d8159825efccd23a) in a way compatible across supported versions of V8.
 467
 468 Signature:
 469
 470 ```c++
 471 Nan::MaybeLocal<v8::String> Nan::GetSourceLine(v8::Local<v8::Message> msg);
 472 ```
 473
 474
 475 <a name="api_nan_get_line_number"></a>
 476 ### Nan::GetLineNumber()
 477
 478 A helper method for calling [`v8::Message#GetLineNumber()`](https://v8docs.nodesource.com/node-8.11/d9/d28/classv8_1_1_message.html#adbe46c10a88a6565f2732a2d2adf99b9) in a way compatible across supported versions of V8.
 479
 480 Signature:
 481
 482 ```c++
 483 Nan::Maybe<int> Nan::GetLineNumber(v8::Local<v8::Message> msg);
 484 ```
 485
 486
 487 <a name="api_nan_get_start_column"></a>
 488 ### Nan::GetStartColumn()
 489
 490 A helper method for calling [`v8::Message#GetStartColumn()`](https://v8docs.nodesource.com/node-8.11/d9/d28/classv8_1_1_message.html#a60ede616ba3822d712e44c7a74487ba6) in a way compatible across supported versions of V8.
 491
 492 Signature:
 493
 494 ```c++
 495 Nan::Maybe<int> Nan::GetStartColumn(v8::Local<v8::Message> msg);
 496 ```
 497
 498
 499 <a name="api_nan_get_end_column"></a>
 500 ### Nan::GetEndColumn()
 501
 502 A helper method for calling [`v8::Message#GetEndColumn()`](https://v8docs.nodesource.com/node-8.11/d9/d28/classv8_1_1_message.html#aaa004cf19e529da980bc19fcb76d93be) in a way compatible across supported versions of V8.
 503
 504 Signature:
 505
 506 ```c++
 507 Nan::Maybe<int> Nan::GetEndColumn(v8::Local<v8::Message> msg);
 508 ```
 509
 510
 511 <a name="api_nan_clone_element_at"></a>
 512 ### Nan::CloneElementAt()
 513
 514 A helper method for calling [`v8::Array#CloneElementAt()`](https://v8docs.nodesource.com/node-4.8/d3/d32/classv8_1_1_array.html#a1d3a878d4c1c7cae974dd50a1639245e) in a way compatible across supported versions of V8.
 515
 516 Signature:
 517
 518 ```c++
 519 Nan::MaybeLocal<v8::Object> Nan::CloneElementAt(v8::Local<v8::Array> array, uint32_t index);
 520 ```
 521
 522 <a name="api_nan_has_private"></a>
 523 ### Nan::HasPrivate()
 524
 525 A helper method for calling [`v8::Object#HasPrivate()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#af68a0b98066cfdeb8f943e98a40ba08d) in a way compatible across supported versions of V8.
 526
 527 Signature:
 528
 529 ```c++
 530 Nan::Maybe<bool> Nan::HasPrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key);
 531 ```
 532
 533 <a name="api_nan_get_private"></a>
 534 ### Nan::GetPrivate()
 535
 536 A helper method for calling [`v8::Object#GetPrivate()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a169f2da506acbec34deadd9149a1925a) in a way compatible across supported versions of V8.
 537
 538 Signature:
 539
 540 ```c++
 541 Nan::MaybeLocal<v8::Value> Nan::GetPrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key);
 542 ```
 543
 544 <a name="api_nan_set_private"></a>
 545 ### Nan::SetPrivate()
 546
 547 A helper method for calling [`v8::Object#SetPrivate()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#ace1769b0f3b86bfe9fda1010916360ee) in a way compatible across supported versions of V8.
 548
 549 Signature:
 550
 551 ```c++
 552 Nan::Maybe<bool> Nan::SetPrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key, v8::Local<v8::Value> value);
 553 ```
 554
 555 <a name="api_nan_delete_private"></a>
 556 ### Nan::DeletePrivate()
 557
 558 A helper method for calling [`v8::Object#DeletePrivate()`](https://v8docs.nodesource.com/node-8.11/db/d85/classv8_1_1_object.html#a138bb32a304f3982be02ad499693b8fd) in a way compatible across supported versions of V8.
 559
 560 Signature:
 561
 562 ```c++
 563 Nan::Maybe<bool> Nan::DeletePrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key);
 564 ```
 565
 566 <a name="api_nan_make_maybe"></a>
 567 ### Nan::MakeMaybe()
 568
 569 Wraps a `v8::Local<>` in a `Nan::MaybeLocal<>`. When called with a `Nan::MaybeLocal<>` it just returns its argument. This is useful in generic template code that builds on NAN.
 570
 571 Synopsis:
 572
 573 ```c++
 574   MaybeLocal<v8::Number> someNumber = MakeMaybe(New<v8::Number>(3.141592654));
 575   MaybeLocal<v8::String> someString = MakeMaybe(New<v8::String>("probably"));
 576 ```
 577
 578 Signature:
 579
 580 ```c++
 581 template <typename T, template <typename> class MaybeMaybe>
 582 Nan::MaybeLocal<T> Nan::MakeMaybe(MaybeMaybe<T> v);
 583 ```