std.locale

[Sean Kelly]

Georg Wrede wrote:
> Sean Kelly wrote:
>> == Quote from Walter Bright (newshound1 at digitalmars.com)'s article
>>> Andrei Alexandrescu wrote:
>>>> I agree. I'm having the same problem: I put a contract in there, I know
>>>> it's as good as assert. So I can't do e.g. input validation because in
>>>> most functions input must always be validated. I also know that
>>>> contracts are doing the wrong thing with inheritance and can't apply to
>>>> interfaces, which is exactly the (only?) place they'd be 
>>>> interesting. So
>>>> I send the contracts home and use assert, enforce, and unittest.
>>> Contracts are not for input validation! They are checking if the logic
>>> of your program is correct or not. Think of it this way - your program
>>> should behave exactly the same with or without the contracts turned on.
>>> Contracts should NOT be used for scrubbing user input, checking for
>>> errors from other components, or validating any input from external to
>>> the dll.
>>
>> Why should contracts be limited to parameter checking of internally used
>> functions only?  If I write a function and document parameter constraints
>> then I certainly expect those constraints to be followed regardless of
>> whether I'm calling the function or someone else is calling the function.
>> Checking these via a contract simply provides an optional means of
>> ensuring that a logic error didn't occur within the program as a whole.
> 
> The distinction is not whether you or others write stuff. It's about 
> whether it is for debugging *only*, as opposed to general input validation.

So I guess the real question is whether a function is expected to 
validate its parameters.  I'd argue that it isn't, but then I'm from a 
C/C++ background.  For me, validation is a debugging tool, or at least 
an optional feature for applications that want the added insurance.


Sean