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83 lines
2.6 KiB
83 lines
2.6 KiB
4 years ago
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# EscapableHandleScope
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The `Napi::EscapableHandleScope` class is used to manage the lifetime of object handles
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which are created through the use of node-addon-api. These handles
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keep an object alive in the heap in order to ensure that the objects
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are not collected by the garbage collector while native code is using them.
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A handle may be created when any new node-addon-api Value or one
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of its subclasses is created or returned.
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The `Napi::EscapableHandleScope` is a special type of `Napi::HandleScope`
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which allows a single handle to be "promoted" to an outer scope.
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For more details refer to the section titled
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[Object lifetime management](object_lifetime_management.md).
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## Methods
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### Constructor
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Creates a new escapable handle scope.
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```cpp
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Napi::EscapableHandleScope Napi::EscapableHandleScope::New(Napi:Env env);
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```
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- `[in] Env`: The environment in which to construct the `Napi::EscapableHandleScope` object.
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Returns a new `Napi::EscapableHandleScope`
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### Constructor
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Creates a new escapable handle scope.
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```cpp
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Napi::EscapableHandleScope Napi::EscapableHandleScope::New(napi_env env, napi_handle_scope scope);
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```
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- `[in] env`: napi_env in which the scope passed in was created.
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- `[in] scope`: pre-existing napi_handle_scope.
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Returns a new `Napi::EscapableHandleScope` instance which wraps the
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napi_escapable_handle_scope handle passed in. This can be used
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to mix usage of the C N-API and node-addon-api.
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operator EscapableHandleScope::napi_escapable_handle_scope
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```cpp
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operator Napi::EscapableHandleScope::napi_escapable_handle_scope() const
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```
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Returns the N-API napi_escapable_handle_scope wrapped by the `Napi::EscapableHandleScope` object.
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This can be used to mix usage of the C N-API and node-addon-api by allowing
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the class to be used be converted to a napi_escapable_handle_scope.
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### Destructor
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```cpp
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Napi::EscapableHandleScope::~EscapableHandleScope();
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```
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Deletes the `Napi::EscapableHandleScope` instance and allows any objects/handles created
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in the scope to be collected by the garbage collector. There is no
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guarantee as to when the gargbage collector will do this.
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### Escape
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```cpp
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napi::Value Napi::EscapableHandleScope::Escape(napi_value escapee);
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```
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- `[in] escapee`: Napi::Value or napi_env to promote to the outer scope
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Returns `Napi::Value` which can be used in the outer scope. This method can
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be called at most once on a given `Napi::EscapableHandleScope`. If it is called
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more than once an exception will be thrown.
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### Env
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```cpp
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Napi::Env Napi::EscapableHandleScope::Env() const;
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```
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Returns the `Napi::Env` associated with the `Napi::EscapableHandleScope`.
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