Type conversion functions

These functions convert values of one type into another type, if possible. All of these functions take a single argument of arbitrary type, and return the result of the type corresponding to the name of the function.

bool(x)

Converts its argument into a boolean value.

• If x is already a boolean, then it returns the argument as-is.

• If x is numeric, then the result is false when x is 0, and true for all other values of x.

• If x is string, then the function will check whether that string can be found within YarnProject.trueValues or YarnProject.falseValues sets. If yes, then it will return the true / false value respectively. Otherwise, an error will be thrown.

number(x)

Converts its argument x into a numeric value.

• If x is boolean, then it returns 1 for true and 0 for false.

• If x is numeric, then it is returned unmodified.

• If x is string, then the function attempts to parse that string as a number. A runtime exception will be raised if x does not have a valid format for a number. The following formats are recognized:

  • integer: "-3", "214"

  • decimal: "0.745", "3.14159", ".1", "-3."

  • scientific: "2e5", "3.11e-05"

  • hexadecimal: "0xDEAD", "0x7F"

string(x)

Converts its argument x into a string value.

• If x is boolean, returns strings "true" or "false".

• If x is numeric, converts it into a string representation using the standard Dart’s .toString() method, which attempts to produce the shortest string that can represent the number x. In particular,

  • if x is integer-valued, returns its decimal representation without a decimal point;

  • if x is a double in the range 1e-6 to 1e21, returns its decimal representation with a decimal point;

  • for all other doubles, returns x written in the scientific (exponential) format.

• If x is a string, then it is returned as-is.