Hi,
I would like to propose changing unicodescalar initializer to failable.
Currently, when you pass an invalid value to the UnicodeScalar initializer the
swift stdlib crashes the program by calling _precondition. This is bad if you
construct a unicode scalar from unknown input.
As a result. I would like to propose to mark the initializer as failable and
return nil in case of a failure.
Currently, in the code below, the stdlib crashes the program by calling
_precondition if codepoint is not a valid unicode.
var string = “"
let codepoint: UInt32 = 55357 // this is invalid
let ucode = UnicodeScalar(codepoint) // Program crashes at this point.
string.append(code)
After marking the initializer as failable, users can write code like this. And
the program will execute fine even codepoint is invalid.
var string = "" let codepoint: UInt32 = 55357 // this is invalid
let ucode = UnicodeScalar(codepoint)
if ucode != nil {
string.append(code!)
} else {
// do something else
}
As the initializer is now failable, it returns an optional, so optional
unchaining or forced unwrapping needs to be used. Alternatively, its also
possible to leave status quo and force the users to do input checks
before trying to construct a UnicodeScalar. But i feel having failable
initializer helps user to write more robust code.
-Xin _______________________________________________
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