Square brackets [] are used to specify optional, positional parameters in Dart. readFile(String name, [String mode, String charset = ‘utf-8’]) { // … } For such declaration name is always required while mode and charset are optional.
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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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