[Gambas-user] Optional and Param (Gambas 3)

[Jussi Lahtinen]

I'm used to do this kind of things like this:

Public Sub _new(Optional x As Float = -1, Optional y As Float = -1
,Optional z As Float = -1)
 If x <> -1 Then v[0] = x
 If y <> -1 Then v[1] = y
 If z <> -1 Then v[2] = z
End


Jussi


2010/6/10 Benoît Minisini <gambas at ...1...>:
>> On 10/06/10 15:38, Charlie Reinl wrote:
>> > Am Donnerstag, den 10.06.2010, 14:37 +0800 schrieb Werner:
>> >> I'm trying to implement a simple class that creates a Float[3] array. I
>> >> would like to give the user of the class an optional opportunity to fill
>> >> the array with data when the class is instantiated.
>> >>
>> >> ----------------------------------------
>> >> ' Gambas class file
>> >> ' Vector3f Class
>> >>
>> >> Public v As New Float[3]
>> >>
>> >> Public Sub _new(Optional x As Float, y As Float, z As Float)
>> >>
>> >>   If Param.Count > 0 Then v[0] = x
>> >>   If Param.Count > 1 Then v[1] = y
>> >>   If Param.Count > 2 Then v[2] = z
>> >>
>> >> End
>> >> ---------------------------------------
>> >>
>> >> The above does not work because Param.Count is always 0 no matter if
>> >> parameter values are supplied or not. My guess is that's because
>> >> Optional can only be used from the second parameter onwards (why?).
>> >>
>> >> How can I make this class do what it should?
>> >>
>> >> Thanks
>> >> Werner Dahn
>> >
>> > Salut Werner,
>> >
>> > where Param is filled? , what is Param ? an array? the class ?
>> >
>> > for Optional, I do not know if it can be chained like you do.
>> > But it can be used also on the first Parameter.
>>
>> Param is a Gambas Class. It can be used to find out how many parameters
>> are supplied to a routine. It's just the way my example is written it
>> always gives a Count of zero, no matter how many parameters are actually
>> supplied.
>> http://gambasdoc.org/help/comp/gb/param
>>
>>
>> Regards
>> Werner
>>
>
> Param is only useful inside a method that takes a "variable number of
> arguments", i.e. whose argument list ends with "...".
>
> You cannot use it for optional arguments. Maybe the documentation is not clear
> enough, as you thought that.
>
> Optional arguments that are not passed by the caller just take their default
> value.
>
> Regards,
>
>
> --
> Benoît Minisini
>
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