Promise object¶

This object represents the eventual outcome of an asynchronous operation and its return data.

A promise can be in one of the following state:

Pending - The asynchronous operation is still in progress
Success - The asynchronous operation concluded with success
Failed - The asynchronous operation concluded with error or failure

Once a Promise has been resolved to either “Success” or “Failed”, its state is sealed along with its associated data or error message

Characteristics¶

Properties¶

Propriedade	Tipo	Descrição

Methods¶

Método	Descrição
promise:thenDo(successCallback)	Set a continuation callback function that will be called when the Promise resolves to success. Arguments: successCallback - A function that will be called when the Promise resolves to success. The first argument of the callback function will receive the associated success data. Remarks: If the Promise is already in a success state, the successCallback will be called as soon as possible Return: A new Promise object that will be resolved asynchronously with the execution of the successCallback. Example: local promise = Firecast.asyncOpenUserNDB("name"); promise:thenDo( function(node) -- This function will be called when the Promise is resolved -- successfully. The first argument, "node", contains the -- Promise success data, which in this case is an opened -- nodeDatabse end);
promise:thenDo(successCallback, failureCallback)	Set continuation callback functions that will be called when the Promise resolves to success or failure. Arguments: successCallback - A function that will be called if the Promise resolves to success. The first argument of the callback function will receive the associated success data failureCallback - A function that will be called if the Promise resolves to failure. The first argument of the callback function will receive the error message. Remarks: This will monitor the Promise for both success and failure states at the same time If the Promise is already in a success state, the successCallback will be called as soon as possible. If the Promise is already in a failure state, the failureCallback will be called as soon as possible If the “successCallback” is called, “failureCallback” will never be called and vice versa. Return: A new Promise object that will be resolved asynchronously with the execution of either the successCallback or failureCallback Example: local promise = Firecast.asyncOpenUserNDB("name"); promise:thenDo( function(node) -- This function will be called when/if the * -- Promise is resolved successfully. The first argument, -- "node", contains the Promise success data, -- which in this case is an opened nodeDatabase end, function(errorMsg) -- This function will be called when/if the * -- Promise is resolved to failure. The first argument, -- "errorMsg", contains the associated error message, -- which in this case is the message explaining why -- it was not possible to open the nodeDatabase end);
promise:onError(failureCallback)	Set a continuation callback function that will be called when the Promise resolves to failure. Arguments: failureCallback - A function that will be called if the Promise resolves to failure. The first argument of the callback function will receive the error message. Remarks: If the Promise is already in a failure state, the failureCallback will be called as soon as possible Return: A new Promise object that will be resolved asynchronously with the execution of failureCallback Example: local promise = Firecast.asyncOpenUserNDB("name"); promise:onError( function(errorMsg) -- This function will be called when/if the -- Promise is resolved to failure. The first argument, -- "errorMsg", contains the associated error message, -- which in this case is the message explaining why -- it was not possible to open the nodeDatabase end);

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