What is a type error?
pc at p-cos.net
Fri Jun 23 13:39:53 CEST 2006
Chris Smith wrote:
> Pascal Costanza <pc at p-cos.net> wrote:
>> What about this: You get a type error when the program attempts to
>> invoke an operation on values that are not appropriate for this operation.
>> Examples: adding numbers to strings; determining the string-length of a
>> number; applying a function on the wrong number of parameters; applying
>> a non-function; accessing an array with out-of-bound indexes; etc.
> Hmm. I'm afraid I'm going to be picky here. I think you need to
> clarify what is meant by "appropriate".
No, I cannot be a lot clearer here. What operations are appropriate for
what values largely depends on the intentions of a programmer. Adding a
number to a string is inappropriate, no matter how a program behaves
when this actually occurs (whether it continues to execute the operation
blindly, throws a continuable exception, or just gets stuck).
> If you mean "the operation will
> not complete successfully" as I suspect you do, then we're closer...
No, we're not. You're giving a purely technical definition here, that
may or may not relate to the programmer's (or "designer's")
understanding of the domain.
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