BlindWatchMaker1 require

[dennis]

In these two snippets:

def runSingleStepSelection(goal as String, alphabet as String) as float
        require
            goal.length
            alphabet.length

def randomString(length as int, alphabet as String) as String
        require
            length > 0
            alphabet <> ''

are alphabet.length and alphabet <> '' equivalent?

[AlGonzalez]

Logically yes, but of course you would have to look at the IL code to know if it is implemented the same.

As for Cobra, if you look at the generated C# code, it tests this for the first one:

Code: Select all

if (!(0!=(alphabet.Length)))

and this for the second

Code: Select all

if (!(alphabet!=""))

[Charles]

When the type is non-nil ("String" instead of "String?"), they're equivalent boolean expressions and you can use either one.
I still haven't decided which one I like best.

If the type is nilable ("String?") then you would want to guard the .length access with "arg and arg.length" which is equivalent to saying "arg is not nil and arg.length".