Rust is a powerful systems-level language that has advanced many of the core programming concepts that have been around for decades in languages like C. Rust provides match statements in which programmers can create concise syntactic handling of complex conditional situations.<\/p>\n
A scrutinee is an expression that is matched in Rust Rust match statements use a scrutinee which is the subject of conditional consideration. In other words, the scrutinee is the variable by which Rust match statements are realized. Let’s consider an example:<\/p>\n Here we see the variable The Rust language offers an Rusts If-Let statement destructures (i.e.\u00a0unpacks<\/em>) the tuple For more information on how scrutinees are used in the Rust language, the following resources will be helpful:<\/p>\nmatch<\/code> and if-let<\/code> statements such that logical handling is possible based on a variable’s value. The use of scrutinees in match<\/code> statements is clear, though the if-let<\/code> statements can require a bit more consideration to fully grasp. Below are examples of each with some explanation and identification of the scrutinee in either case.<\/p>\nScrutinees in Match Statements<\/h2>\n
fn main(){\r\n\r\n \/\/ Defines a variable \"day\"\r\n let day = 5;\r\n\r\n \/\/ \"day\" becomes the scrutinee of the match statement\r\n match day {\r\n\r\n \/\/ Take action based on scrutinee (day) value\r\n 1 => println!(\"Monday\"),\r\n 2 => println!(\"Tuesday\"),\r\n 3 => println!(\"Wednesday\"),\r\n 4 => println!(\"Thursday\"),\r\n 5 => println!(\"Friday\"),\r\n 6 => println!(\"Saturday\"),\r\n 7 => println!(\"Sunday\"),\r\n _ => println!(\"Must be Fribsday!\"),\r\n }\r\n}<\/pre>\nday<\/code> become the scrutinee<\/strong> of the match statement. Based on the value of day<\/code>, the match statement will print out the value accordingly. Since Rust match statements are exhaustive<\/em>, we have included the _<\/code> case at the end.<\/p>\nScrutinees in If-Let Statements<\/h2>\n
if-let<\/code> conditional syntax that can greatly simplify conditional statements in some cases. Particularly, it lessens the amount of code for matching certain structures. These statements can be used to restructure objects as well. Consider the following:<\/p>\nfn main() {\r\n\r\n \/\/ Defines a tuple of options\r\n let choice = (\"one\", \"other\");\r\n\r\n \/\/ Prints a statement conditional on the first value\r\n \/\/ of the options be equal to \"one\" while destructuring\r\n \/\/ the tuple to make available the second value, assigned\r\n \/\/ to the variable b.\r\n if let (\"one\", b) = choice {\r\n println!(\"One is not like the {}\", b);\r\n }else{\r\n println!(\"The other is not like one\");\r\n }\r\n \r\n}<\/pre>\nchoice<\/code> allowing access to the values of the individual elements. The if<\/code> part of this statement checks if the first value of the choice<\/code> variable (the\u00a0scrutinee<\/em>) is equal to one<\/code> and, if so, handles that case in the first block where the second element of the choice<\/code> tuple, other<\/code>, is made available as the variable b<\/code>. The else<\/code> portion of this block handles the only other case \u2014 one<\/code>\u00a0not<\/em> being the first element.<\/p>\nResources<\/h2>\n