On 12-May-07, at 6:33 PM, Kiam wrote:
> ----- Original Message -----
> From: "Norman Palardy" <[EMAIL PROTECTED]>
> To: "REALbasic NUG" <[email protected]>
> Sent: Saturday, May 05, 2007 11:49 PM
> Subject: Re: overriding operator_convert not working?
>
>>
>> On 5-May-07, at 2:21 PM, kev wrote:
>>
>>> So I guess there's no way around this that will also maintain
>>> polymorphism?
>>
>> Use a constructor that takes a string ?
>>
>
> I think there is a little confusion around Operator_Convert().
> It should be used to convert from any datatype to a class instance.
> So if I
> declare a Operator_Convert(input As String) in a class called
> TestConvert,
> then I can write
>
> Dim value As New TestConvert
> value = "test"
>
> There is no need to control the class of the object, as long as the
> class
> provides a right Operator_Convert().
Operator_Convert acts like a constructor.
If you have a class, like the original poster did, with a subclass
and both have operator_convert implemented you get what appears to be
odd behavior when you do something like
dim v as SuperClassType
v = new SubClassType
v = "test" // if you check after doing this V is an instance of
SuperClassType NOT SubClassType
in this case the operator_convert called is the on in the DEFINED
type of v (the one in the super class) because operator_convert does
behave as a constructor and just a "conversion" from string to the
type of v.
It's more like doing
v = new SuperClassType
v.TakeAStringAndAssignItToV("test")
and this TakeAStringAndAssignItToV is your custom method to rip a
string into the various members of an instance of SuperClassType
Basically don't use operator_convert where you really want a
constructor that takes a string because you can end up with
unexpected behavior like this
If the original poster had written
dim v as SuperClassType
v = new SubClassType("test")
v would have been of the SubClassType as expected
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