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Mojo trait

StringableRaising

The StringableRaising trait describes a type that can be converted to a String.

Any type that conforms to Stringable or StringableRaising works with the built-in print() and str() functions.

The StringableRaising trait requires the type to define the __str__() method, which can raise an error. For example:

@value
struct Foo(StringableRaising):
    var s: String

    fn __str__(self) raises -> String:
        if self.s == "":
            raise Error("Empty String")
        return self.s
@value
struct Foo(StringableRaising):
    var s: String

    fn __str__(self) raises -> String:
        if self.s == "":
            raise Error("Empty String")
        return self.s

Now you can pass an instance of Foo to the str() function to get back a String:

fn main() raises:
    var foo = Foo("test")
    print(str(foo) == "test")
fn main() raises:
    var foo = Foo("test")
    print(str(foo) == "test")
True
True

Implemented traits​

AnyType, UnknownDestructibility

Methods​

__str__​

__str__(self: _Self) -> String

Get the string representation of the type.

Returns:

The string representation of the type.

Raises:

If there is an error when computing the string representation of the type.