77 lines
2.6 KiB
Markdown
77 lines
2.6 KiB
Markdown
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## Nan::Callback
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`Nan::Callback` makes it easier to use `v8::Function` handles as callbacks. A class that wraps a `v8::Function` handle, protecting it from garbage collection and making it particularly useful for storage and use across asynchronous execution.
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- <a href="#api_nan_callback"><b><code>Nan::Callback</code></b></a>
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<a name="api_nan_callback"></a>
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### Nan::Callback
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```c++
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class Callback {
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public:
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Callback();
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explicit Callback(const v8::Local<v8::Function> &fn);
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~Callback();
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bool operator==(const Callback &other) const;
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bool operator!=(const Callback &other) const;
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v8::Local<v8::Function> operator*() const;
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MaybeLocal<v8::Value> operator()(AsyncResource* async_resource,
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v8::Local<v8::Object> target,
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int argc = 0,
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v8::Local<v8::Value> argv[] = 0) const;
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MaybeLocal<v8::Value> operator()(AsyncResource* async_resource,
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int argc = 0,
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v8::Local<v8::Value> argv[] = 0) const;
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void SetFunction(const v8::Local<v8::Function> &fn);
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v8::Local<v8::Function> GetFunction() const;
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bool IsEmpty() const;
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void Reset(const v8::Local<v8::Function> &fn);
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void Reset();
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MaybeLocal<v8::Value> Call(v8::Local<v8::Object> target,
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int argc,
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v8::Local<v8::Value> argv[],
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AsyncResource* async_resource) const;
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MaybeLocal<v8::Value> Call(int argc,
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v8::Local<v8::Value> argv[],
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AsyncResource* async_resource) const;
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// Deprecated versions. Use the versions that accept an async_resource instead
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// as they run the callback in the correct async context as specified by the
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// resource. If you want to call a synchronous JS function (i.e. on a
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// non-empty JS stack), you can use Nan::Call instead.
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v8::Local<v8::Value> operator()(v8::Local<v8::Object> target,
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int argc = 0,
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v8::Local<v8::Value> argv[] = 0) const;
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v8::Local<v8::Value> operator()(int argc = 0,
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v8::Local<v8::Value> argv[] = 0) const;
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v8::Local<v8::Value> Call(v8::Local<v8::Object> target,
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int argc,
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v8::Local<v8::Value> argv[]) const;
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v8::Local<v8::Value> Call(int argc, v8::Local<v8::Value> argv[]) const;
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};
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```
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Example usage:
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```c++
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v8::Local<v8::Function> function;
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Nan::Callback callback(function);
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callback.Call(0, 0);
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```
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