Dart Constructor using Square brackets : Positional optional parameters. You can wrap one or more parameters in square brackets [ ] to make them as optional positional parameters.
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Named optional parameters You can call getHttpUrl with or without the third parameter. You must use the parameter name when calling the function. You can specify multiple named parameters for a function: getHttpUrl(String server, String path, {int port = 80, int numRetries = 3}) { // … } 21 Eyl 2020
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