www.aleph1.co.uk Git - yaffs-website/blob - 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_force_set"><b><code>Nan::ForceSet()</code></b></a>
  19   - <a href="#api_nan_get"><b><code>Nan::Get()</code></b></a>
  20   - <a href="#api_nan_get_property_attribute"><b><code>Nan::GetPropertyAttributes()</code></b></a>
  21   - <a href="#api_nan_has"><b><code>Nan::Has()</code></b></a>
  22   - <a href="#api_nan_delete"><b><code>Nan::Delete()</code></b></a>
  23   - <a href="#api_nan_get_property_names"><b><code>Nan::GetPropertyNames()</code></b></a>
  24   - <a href="#api_nan_get_own_property_names"><b><code>Nan::GetOwnPropertyNames()</code></b></a>
  25   - <a href="#api_nan_set_prototype"><b><code>Nan::SetPrototype()</code></b></a>
  26   - <a href="#api_nan_object_proto_to_string"><b><code>Nan::ObjectProtoToString()</code></b></a>
  27   - <a href="#api_nan_has_own_property"><b><code>Nan::HasOwnProperty()</code></b></a>
  28   - <a href="#api_nan_has_real_named_property"><b><code>Nan::HasRealNamedProperty()</code></b></a>
  29   - <a href="#api_nan_has_real_indexed_property"><b><code>Nan::HasRealIndexedProperty()</code></b></a>
  30   - <a href="#api_nan_has_real_named_callback_property"><b><code>Nan::HasRealNamedCallbackProperty()</code></b></a>
  31   - <a href="#api_nan_get_real_named_property_in_prototype_chain"><b><code>Nan::GetRealNamedPropertyInPrototypeChain()</code></b></a>
  32   - <a href="#api_nan_get_real_named_property"><b><code>Nan::GetRealNamedProperty()</code></b></a>
  33   - <a href="#api_nan_call_as_function"><b><code>Nan::CallAsFunction()</code></b></a>
  34   - <a href="#api_nan_call_as_constructor"><b><code>Nan::CallAsConstructor()</code></b></a>
  35   - <a href="#api_nan_get_source_line"><b><code>Nan::GetSourceLine()</code></b></a>
  36   - <a href="#api_nan_get_line_number"><b><code>Nan::GetLineNumber()</code></b></a>
  37   - <a href="#api_nan_get_start_column"><b><code>Nan::GetStartColumn()</code></b></a>
  38   - <a href="#api_nan_get_end_column"><b><code>Nan::GetEndColumn()</code></b></a>
  39   - <a href="#api_nan_clone_element_at"><b><code>Nan::CloneElementAt()</code></b></a>
  40   - <a href="#api_nan_has_private"><b><code>Nan::HasPrivate()</code></b></a>
  41   - <a href="#api_nan_get_private"><b><code>Nan::GetPrivate()</code></b></a>
  42   - <a href="#api_nan_set_private"><b><code>Nan::SetPrivate()</code></b></a>
  43   - <a href="#api_nan_delete_private"><b><code>Nan::DeletePrivate()</code></b></a>
  44   - <a href="#api_nan_make_maybe"><b><code>Nan::MakeMaybe()</code></b></a>
  45
  46 <a name="api_nan_maybe_local"></a>
  47 ### Nan::MaybeLocal
  48
  49 A `Nan::MaybeLocal<T>` is a wrapper around [`v8::Local<T>`](https://v8docs.nodesource.com/io.js-3.0/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.
  50
  51 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.
  52
  53 Definition:
  54
  55 ```c++
  56 template<typename T> class Nan::MaybeLocal {
  57  public:
  58   MaybeLocal();
  59
  60   template<typename S> MaybeLocal(v8::Local<S> that);
  61
  62   bool IsEmpty() const;
  63
  64   template<typename S> bool ToLocal(v8::Local<S> *out);
  65
  66   // Will crash if the MaybeLocal<> is empty.
  67   v8::Local<T> ToLocalChecked();
  68
  69   template<typename S> v8::Local<S> FromMaybe(v8::Local<S> default_value) const;
  70 };
  71 ```
  72
  73 See the documentation for [`v8::MaybeLocal`](https://v8docs.nodesource.com/io.js-3.0/d8/d7d/classv8_1_1_maybe_local.html) for further details.
  74
  75 <a name="api_nan_maybe"></a>
  76 ### Nan::Maybe
  77
  78 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.
  79
  80 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.
  81
  82 Definition:
  83
  84 ```c++
  85 template<typename T> class Nan::Maybe {
  86  public:
  87   bool IsNothing() const;
  88   bool IsJust() const;
  89
  90   // Will crash if the Maybe<> is nothing.
  91   T FromJust();
  92
  93   T FromMaybe(const T& default_value);
  94
  95   bool operator==(const Maybe &other);
  96
  97   bool operator!=(const Maybe &other);
  98 };
  99 ```
 100
 101 See the documentation for [`v8::Maybe`](https://v8docs.nodesource.com/io.js-3.0/d9/d4b/classv8_1_1_maybe.html) for further details.
 102
 103 <a name="api_nan_nothing"></a>
 104 ### Nan::Nothing
 105
 106 Construct an empty `Nan::Maybe` type representing _nothing_.
 107
 108 ```c++
 109 template<typename T> Nan::Maybe<T> Nan::Nothing();
 110 ```
 111
 112 <a name="api_nan_just"></a>
 113 ### Nan::Just
 114
 115 Construct a `Nan::Maybe` type representing _just_ a value.
 116
 117 ```c++
 118 template<typename T> Nan::Maybe<T> Nan::Just(const T &t);
 119 ```
 120
 121 <a name="api_nan_call"></a>
 122 ### Nan::Call()
 123
 124 A helper method for calling [`v8::Function#Call()`](https://v8docs.nodesource.com/io.js-3.0/d5/d54/classv8_1_1_function.html#a468a89f737af0612db10132799c827c0) in a way compatible across supported versions of V8.
 125
 126 Signature:
 127
 128 ```c++
 129 Nan::MaybeLocal<v8::Value> Nan::Call(v8::Local<v8::Function> fun, v8::Local<v8::Object> recv, int argc, v8::Local<v8::Value> argv[]);
 130 ```
 131
 132
 133 <a name="api_nan_to_detail_string"></a>
 134 ### Nan::ToDetailString()
 135
 136 A helper method for calling [`v8::Value#ToDetailString()`](https://v8docs.nodesource.com/io.js-3.0/dc/d0a/classv8_1_1_value.html#a2f9770296dc2c8d274bc8cc0dca243e5) in a way compatible across supported versions of V8.
 137
 138 Signature:
 139
 140 ```c++
 141 Nan::MaybeLocal<v8::String> Nan::ToDetailString(v8::Local<v8::Value> val);
 142 ```
 143
 144
 145 <a name="api_nan_to_array_index"></a>
 146 ### Nan::ToArrayIndex()
 147
 148 A helper method for calling [`v8::Value#ToArrayIndex()`](https://v8docs.nodesource.com/io.js-3.0/dc/d0a/classv8_1_1_value.html#acc5bbef3c805ec458470c0fcd6f13493) in a way compatible across supported versions of V8.
 149
 150 Signature:
 151
 152 ```c++
 153 Nan::MaybeLocal<v8::Uint32> Nan::ToArrayIndex(v8::Local<v8::Value> val);
 154 ```
 155
 156
 157 <a name="api_nan_equals"></a>
 158 ### Nan::Equals()
 159
 160 A helper method for calling [`v8::Value#Equals()`](https://v8docs.nodesource.com/io.js-3.0/dc/d0a/classv8_1_1_value.html#a0d9616ab2de899d4e3047c30a10c9285) in a way compatible across supported versions of V8.
 161
 162 Signature:
 163
 164 ```c++
 165 Nan::Maybe<bool> Nan::Equals(v8::Local<v8::Value> a, v8::Local<v8::Value>(b));
 166 ```
 167
 168
 169 <a name="api_nan_new_instance"></a>
 170 ### Nan::NewInstance()
 171
 172 A helper method for calling [`v8::Function#NewInstance()`](https://v8docs.nodesource.com/io.js-3.0/d5/d54/classv8_1_1_function.html#a691b13f7a553069732cbacf5ac8c62ec) and [`v8::ObjectTemplate#NewInstance()`](https://v8docs.nodesource.com/io.js-3.0/db/d5f/classv8_1_1_object_template.html#ad605a7543cfbc5dab54cdb0883d14ae4) in a way compatible across supported versions of V8.
 173
 174 Signature:
 175
 176 ```c++
 177 Nan::MaybeLocal<v8::Object> Nan::NewInstance(v8::Local<v8::Function> h);
 178 Nan::MaybeLocal<v8::Object> Nan::NewInstance(v8::Local<v8::Function> h, int argc, v8::Local<v8::Value> argv[]);
 179 Nan::MaybeLocal<v8::Object> Nan::NewInstance(v8::Local<v8::ObjectTemplate> h);
 180 ```
 181
 182
 183 <a name="api_nan_get_function"></a>
 184 ### Nan::GetFunction()
 185
 186 A helper method for calling [`v8::FunctionTemplate#GetFunction()`](https://v8docs.nodesource.com/io.js-3.0/d8/d83/classv8_1_1_function_template.html#a56d904662a86eca78da37d9bb0ed3705) in a way compatible across supported versions of V8.
 187
 188 Signature:
 189
 190 ```c++
 191 Nan::MaybeLocal<v8::Function> Nan::GetFunction(v8::Local<v8::FunctionTemplate> t);
 192 ```
 193
 194
 195 <a name="api_nan_set"></a>
 196 ### Nan::Set()
 197
 198 A helper method for calling [`v8::Object#Set()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#a67604ea3734f170c66026064ea808f20) in a way compatible across supported versions of V8.
 199
 200 Signature:
 201
 202 ```c++
 203 Nan::Maybe<bool> Nan::Set(v8::Local<v8::Object> obj,
 204                           v8::Local<v8::Value> key,
 205                           v8::Local<v8::Value> value)
 206 Nan::Maybe<bool> Nan::Set(v8::Local<v8::Object> obj,
 207                           uint32_t index,
 208                           v8::Local<v8::Value> value);
 209 ```
 210
 211
 212 <a name="api_nan_force_set"></a>
 213 ### Nan::ForceSet()
 214
 215 A helper method for calling [`v8::Object#ForceSet()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#a796b7b682896fb64bf1872747734e836) in a way compatible across supported versions of V8.
 216
 217 Signature:
 218
 219 ```c++
 220 Nan::Maybe<bool> Nan::ForceSet(v8::Local<v8::Object> obj,
 221                                v8::Local<v8::Value> key,
 222                                v8::Local<v8::Value> value,
 223                                v8::PropertyAttribute attribs = v8::None);
 224 ```
 225
 226
 227 <a name="api_nan_get"></a>
 228 ### Nan::Get()
 229
 230 A helper method for calling [`v8::Object#Get()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#a2565f03e736694f6b1e1cf22a0b4eac2) in a way compatible across supported versions of V8.
 231
 232 Signature:
 233
 234 ```c++
 235 Nan::MaybeLocal<v8::Value> Nan::Get(v8::Local<v8::Object> obj,
 236                                     v8::Local<v8::Value> key);
 237 Nan::MaybeLocal<v8::Value> Nan::Get(v8::Local<v8::Object> obj, uint32_t index);
 238 ```
 239
 240
 241 <a name="api_nan_get_property_attribute"></a>
 242 ### Nan::GetPropertyAttributes()
 243
 244 A helper method for calling [`v8::Object#GetPropertyAttributes()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#a9b898894da3d1db2714fd9325a54fe57) in a way compatible across supported versions of V8.
 245
 246 Signature:
 247
 248 ```c++
 249 Nan::Maybe<v8::PropertyAttribute> Nan::GetPropertyAttributes(
 250     v8::Local<v8::Object> obj,
 251     v8::Local<v8::Value> key);
 252 ```
 253
 254
 255 <a name="api_nan_has"></a>
 256 ### Nan::Has()
 257
 258 A helper method for calling [`v8::Object#Has()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#ab3c3d89ea7c2f9afd08965bd7299a41d) in a way compatible across supported versions of V8.
 259
 260 Signature:
 261
 262 ```c++
 263 Nan::Maybe<bool> Nan::Has(v8::Local<v8::Object> obj, v8::Local<v8::String> key);
 264 Nan::Maybe<bool> Nan::Has(v8::Local<v8::Object> obj, uint32_t index);
 265 ```
 266
 267
 268 <a name="api_nan_delete"></a>
 269 ### Nan::Delete()
 270
 271 A helper method for calling [`v8::Object#Delete()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#a2fa0f5a592582434ed1ceceff7d891ef) in a way compatible across supported versions of V8.
 272
 273 Signature:
 274
 275 ```c++
 276 Nan::Maybe<bool> Nan::Delete(v8::Local<v8::Object> obj,
 277                              v8::Local<v8::String> key);
 278 Nan::Maybe<bool> Nan::Delete(v8::Local<v8::Object> obj, uint32_t index);
 279 ```
 280
 281
 282 <a name="api_nan_get_property_names"></a>
 283 ### Nan::GetPropertyNames()
 284
 285 A helper method for calling [`v8::Object#GetPropertyNames()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#aced885270cfd2c956367b5eedc7fbfe8) in a way compatible across supported versions of V8.
 286
 287 Signature:
 288
 289 ```c++
 290 Nan::MaybeLocal<v8::Array> Nan::GetPropertyNames(v8::Local<v8::Object> obj);
 291 ```
 292
 293
 294 <a name="api_nan_get_own_property_names"></a>
 295 ### Nan::GetOwnPropertyNames()
 296
 297 A helper method for calling [`v8::Object#GetOwnPropertyNames()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#a79a6e4d66049b9aa648ed4dfdb23e6eb) in a way compatible across supported versions of V8.
 298
 299 Signature:
 300
 301 ```c++
 302 Nan::MaybeLocal<v8::Array> Nan::GetOwnPropertyNames(v8::Local<v8::Object> obj);
 303 ```
 304
 305
 306 <a name="api_nan_set_prototype"></a>
 307 ### Nan::SetPrototype()
 308
 309 A helper method for calling [`v8::Object#SetPrototype()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#a442706b22fceda6e6d1f632122a9a9f4) in a way compatible across supported versions of V8.
 310
 311 Signature:
 312
 313 ```c++
 314 Nan::Maybe<bool> Nan::SetPrototype(v8::Local<v8::Object> obj,
 315                                    v8::Local<v8::Value> prototype);
 316 ```
 317
 318
 319 <a name="api_nan_object_proto_to_string"></a>
 320 ### Nan::ObjectProtoToString()
 321
 322 A helper method for calling [`v8::Object#ObjectProtoToString()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#ab7a92b4dcf822bef72f6c0ac6fea1f0b) in a way compatible across supported versions of V8.
 323
 324 Signature:
 325
 326 ```c++
 327 Nan::MaybeLocal<v8::String> Nan::ObjectProtoToString(v8::Local<v8::Object> obj);
 328 ```
 329
 330
 331 <a name="api_nan_has_own_property"></a>
 332 ### Nan::HasOwnProperty()
 333
 334 A helper method for calling [`v8::Object#HasOwnProperty()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#ab7b7245442ca6de1e1c145ea3fd653ff) in a way compatible across supported versions of V8.
 335
 336 Signature:
 337
 338 ```c++
 339 Nan::Maybe<bool> Nan::HasOwnProperty(v8::Local<v8::Object> obj,
 340                                      v8::Local<v8::String> key);
 341 ```
 342
 343
 344 <a name="api_nan_has_real_named_property"></a>
 345 ### Nan::HasRealNamedProperty()
 346
 347 A helper method for calling [`v8::Object#HasRealNamedProperty()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#ad8b80a59c9eb3c1e6c3cd6c84571f767) in a way compatible across supported versions of V8.
 348
 349 Signature:
 350
 351 ```c++
 352 Nan::Maybe<bool> Nan::HasRealNamedProperty(v8::Local<v8::Object> obj,
 353                                            v8::Local<v8::String> key);
 354 ```
 355
 356
 357 <a name="api_nan_has_real_indexed_property"></a>
 358 ### Nan::HasRealIndexedProperty()
 359
 360 A helper method for calling [`v8::Object#HasRealIndexedProperty()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#af94fc1135a5e74a2193fb72c3a1b9855) in a way compatible across supported versions of V8.
 361
 362 Signature:
 363
 364 ```c++
 365 Nan::Maybe<bool> Nan::HasRealIndexedProperty(v8::Local<v8::Object> obj,
 366                                              uint32_t index);
 367 ```
 368
 369
 370 <a name="api_nan_has_real_named_callback_property"></a>
 371 ### Nan::HasRealNamedCallbackProperty()
 372
 373 A helper method for calling [`v8::Object#HasRealNamedCallbackProperty()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#af743b7ea132b89f84d34d164d0668811) in a way compatible across supported versions of V8.
 374
 375 Signature:
 376
 377 ```c++
 378 Nan::Maybe<bool> Nan::HasRealNamedCallbackProperty(
 379     v8::Local<v8::Object> obj,
 380     v8::Local<v8::String> key);
 381 ```
 382
 383
 384 <a name="api_nan_get_real_named_property_in_prototype_chain"></a>
 385 ### Nan::GetRealNamedPropertyInPrototypeChain()
 386
 387 A helper method for calling [`v8::Object#GetRealNamedPropertyInPrototypeChain()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#a8700b1862e6b4783716964ba4d5e6172) in a way compatible across supported versions of V8.
 388
 389 Signature:
 390
 391 ```c++
 392 Nan::MaybeLocal<v8::Value> Nan::GetRealNamedPropertyInPrototypeChain(
 393     v8::Local<v8::Object> obj,
 394     v8::Local<v8::String> key);
 395 ```
 396
 397
 398 <a name="api_nan_get_real_named_property"></a>
 399 ### Nan::GetRealNamedProperty()
 400
 401 A helper method for calling [`v8::Object#GetRealNamedProperty()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#a84471a824576a5994fdd0ffcbf99ccc0) in a way compatible across supported versions of V8.
 402
 403 Signature:
 404
 405 ```c++
 406 Nan::MaybeLocal<v8::Value> Nan::GetRealNamedProperty(v8::Local<v8::Object> obj,
 407                                                      v8::Local<v8::String> key);
 408 ```
 409
 410
 411 <a name="api_nan_call_as_function"></a>
 412 ### Nan::CallAsFunction()
 413
 414 A helper method for calling [`v8::Object#CallAsFunction()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#a9ef18be634e79b4f0cdffa1667a29f58) in a way compatible across supported versions of V8.
 415
 416 Signature:
 417
 418 ```c++
 419 Nan::MaybeLocal<v8::Value> Nan::CallAsFunction(v8::Local<v8::Object> obj,
 420                                                v8::Local<v8::Object> recv,
 421                                                int argc,
 422                                                v8::Local<v8::Value> argv[]);
 423 ```
 424
 425
 426 <a name="api_nan_call_as_constructor"></a>
 427 ### Nan::CallAsConstructor()
 428
 429 A helper method for calling [`v8::Object#CallAsConstructor()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#a50d571de50d0b0dfb28795619d07a01b) in a way compatible across supported versions of V8.
 430
 431 Signature:
 432
 433 ```c++
 434 Nan::MaybeLocal<v8::Value> Nan::CallAsConstructor(v8::Local<v8::Object> obj,
 435                                                   int argc,
 436                                                   v8::Local<v8::Value> argv[]);
 437 ```
 438
 439
 440 <a name="api_nan_get_source_line"></a>
 441 ### Nan::GetSourceLine()
 442
 443 A helper method for calling [`v8::Message#GetSourceLine()`](https://v8docs.nodesource.com/io.js-3.0/d9/d28/classv8_1_1_message.html#a849f7a6c41549d83d8159825efccd23a) in a way compatible across supported versions of V8.
 444
 445 Signature:
 446
 447 ```c++
 448 Nan::MaybeLocal<v8::String> Nan::GetSourceLine(v8::Local<v8::Message> msg);
 449 ```
 450
 451
 452 <a name="api_nan_get_line_number"></a>
 453 ### Nan::GetLineNumber()
 454
 455 A helper method for calling [`v8::Message#GetLineNumber()`](https://v8docs.nodesource.com/io.js-3.0/d9/d28/classv8_1_1_message.html#adbe46c10a88a6565f2732a2d2adf99b9) in a way compatible across supported versions of V8.
 456
 457 Signature:
 458
 459 ```c++
 460 Nan::Maybe<int> Nan::GetLineNumber(v8::Local<v8::Message> msg);
 461 ```
 462
 463
 464 <a name="api_nan_get_start_column"></a>
 465 ### Nan::GetStartColumn()
 466
 467 A helper method for calling [`v8::Message#GetStartColumn()`](https://v8docs.nodesource.com/io.js-3.0/d9/d28/classv8_1_1_message.html#a60ede616ba3822d712e44c7a74487ba6) in a way compatible across supported versions of V8.
 468
 469 Signature:
 470
 471 ```c++
 472 Nan::Maybe<int> Nan::GetStartColumn(v8::Local<v8::Message> msg);
 473 ```
 474
 475
 476 <a name="api_nan_get_end_column"></a>
 477 ### Nan::GetEndColumn()
 478
 479 A helper method for calling [`v8::Message#GetEndColumn()`](https://v8docs.nodesource.com/io.js-3.0/d9/d28/classv8_1_1_message.html#aaa004cf19e529da980bc19fcb76d93be) in a way compatible across supported versions of V8.
 480
 481 Signature:
 482
 483 ```c++
 484 Nan::Maybe<int> Nan::GetEndColumn(v8::Local<v8::Message> msg);
 485 ```
 486
 487
 488 <a name="api_nan_clone_element_at"></a>
 489 ### Nan::CloneElementAt()
 490
 491 A helper method for calling [`v8::Array#CloneElementAt()`](https://v8docs.nodesource.com/io.js-3.0/d3/d32/classv8_1_1_array.html#a1d3a878d4c1c7cae974dd50a1639245e) in a way compatible across supported versions of V8.
 492
 493 Signature:
 494
 495 ```c++
 496 Nan::MaybeLocal<v8::Object> Nan::CloneElementAt(v8::Local<v8::Array> array, uint32_t index);
 497 ```
 498
 499 <a name="api_nan_has_private"></a>
 500 ### Nan::HasPrivate()
 501
 502 A helper method for calling [`v8::Object#HasPrivate()`](https://v8docs.nodesource.com/node-7.2/db/d85/classv8_1_1_object.html#af68a0b98066cfdeb8f943e98a40ba08d) in a way compatible across supported versions of V8.
 503
 504 Signature:
 505
 506 ```c++
 507 Nan::Maybe<bool> Nan::HasPrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key);
 508 ```
 509
 510 <a name="api_nan_get_private"></a>
 511 ### Nan::GetPrivate()
 512
 513 A helper method for calling [`v8::Object#GetPrivate()`](https://v8docs.nodesource.com/node-7.2/db/d85/classv8_1_1_object.html#a169f2da506acbec34deadd9149a1925a) in a way compatible across supported versions of V8.
 514
 515 Signature:
 516
 517 ```c++
 518 Nan::MaybeLocal<v8::Value> Nan::GetPrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key);
 519 ```
 520
 521 <a name="api_nan_set_private"></a>
 522 ### Nan::SetPrivate()
 523
 524 A helper method for calling [`v8::Object#SetPrivate()`](https://v8docs.nodesource.com/node-7.2/db/d85/classv8_1_1_object.html#ace1769b0f3b86bfe9fda1010916360ee) in a way compatible across supported versions of V8.
 525
 526 Signature:
 527
 528 ```c++
 529 Nan::Maybe<bool> Nan::SetPrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key, v8::Local<v8::Value> value);
 530 ```
 531
 532 <a name="api_nan_delete_private"></a>
 533 ### Nan::DeletePrivate()
 534
 535 A helper method for calling [`v8::Object#DeletePrivate()`](https://v8docs.nodesource.com/node-7.2/db/d85/classv8_1_1_object.html#a138bb32a304f3982be02ad499693b8fd) in a way compatible across supported versions of V8.
 536
 537 Signature:
 538
 539 ```c++
 540 Nan::Maybe<bool> Nan::DeletePrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key);
 541 ```
 542
 543 <a name="api_nan_make_maybe"></a>
 544 ### Nan::MakeMaybe()
 545
 546 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.
 547
 548 Synopsis:
 549
 550 ```c++
 551   MaybeLocal<v8::Number> someNumber = MakeMaybe(New<v8::Number>(3.141592654));
 552   MaybeLocal<v8::String> someString = MakeMaybe(New<v8::String>("probably"));
 553 ```
 554
 555 Signature:
 556
 557 ```c++
 558 template <typename T, template <typename> class MaybeMaybe>
 559 Nan::MaybeLocal<T> Nan::MakeMaybe(MaybeMaybe<T> v);
 560 ```