Types as Optional Parameters

Blitz3D Forums/Blitz3D Beginners Area/Types as Optional Parameters

HappyCat

(Posted 2004) [#1]

Can you do things like:

Function DoSomething(SomeObject.SomeType = Null)

I'm assuming not as I can't get it to work.

semar

(Posted 2004) [#2]

soja	(Posted 2004) [#3]

I don't think so.

Tiger

(Posted 2004) [#4]

Its not possible with blitz.

N	(Posted 2004) [#5]

Null is not a constant value, so no,it's impossible.

morduun

(Posted 2004) [#6]

Not possible.

Type myType
	Field blah
End Type

Function myFunction(myInstance.myType = Null)
	Return myInstance\blah
End Function

returns an error.

You'd think a fellow who's done more with Blitz3D in the last year than most people have ever done would know something like that, eh? >:D

[EDIT] ROFL: nice edit Noel. Undoubtedly revisionist history accounts for some of that expertise of yours eh? XD[/EDIT]

767pilot

(Posted 2004) [#7]

yeah, even I knew that.

but then again maybe im just lying!! :)

N	(Posted 2004) [#8]

It's interesting considering it didn't work for me in the past. I shall have to try this again.

DJWoodgate

(Posted 2004) [#9]

I suppose you could use the handle and object method. Probably not like this, but it's just an example.

Type myType
	Field blah
End Type

Instance.mytype = myfunction(10)

Print Instance\blah

myfunction(20,Handle(Instance))

Print Instance\blah


WaitKey()

Function myFunction.mytype(value,typehandle=0)
	Local thisinstance.mytype = Object.mytype(typehandle)
	If thisinstance<>Null 
		thisinstance\blah = value
	Else 
		thisinstance = New mytype
		thisinstance\blah = value
	EndIf
	Return thisinstance
End Function

sswift

(Posted 2004) [#10]

Someone once tried to explain to me why this is impossible, but I didn't understand what they were trying to say. It seems trivial to me.

HappyCat

(Posted 2004) [#11]

Yeah, I find it a bit of a strange omission - I'm sure there must be a good reason.

Never mind, I'll just have to get used to passing in "Null"s instead :-)

Tibit

(Posted 2004) [#12]

Function DoSomething(SomeObject.SomeType = Null)

Well this is possible like DJWoodGate said. You can't write it that way, but you can have the same "functionality". But I might have gotten you wrong, Test this sample.

[code]
Function DrawEntry(Pointer%=0)

Local P.SomeType = Object.SomeType Pointer

If P <> Null;Did they send a long an object or just a ZERO?
;Good
Text P\x,P\y,"- Object Verified -"
Else
Text 0,Rand(100),"- Object NOT Verified - or none Found"
End If

End Function

Type SomeType
Field X,Y
End Type

P.SomeType = New SomeType
P\X = 21:P\Y = 50
P2.SomeType = New SomeType
P2\X = 75:P2\Y = 20

DrawEntry(Handle P)
DrawEntry(Handle P2)
DrawEntry(0)
WaitKey()
[code/]