Difference between revisions of "User Defined Function"
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User defined functions (UDF) are added by NVSE V4. They must be saved as 'object' type scripts that must use the "Function" block type only. Although 'object' type, they must not be attached to any object and are instead called directly by script name from within other scripts, using the [[Call]] command. | User defined functions (UDF) are added by NVSE V4. They must be saved as 'object' type scripts that must use the "Function" block type only. Although 'object' type, they must not be attached to any object and are instead called directly by script name from within other scripts, using the [[Call]] command. | ||
UDFs may optionally return a single value of any type, using the [[SetFunctionValue]] command within them. They may optionally accept | UDFs may optionally return a single value of any type, using the [[SetFunctionValue]] command within them. They may optionally accept up to 15 arguments of any type, which are defined within curly braces: | ||
<pre> | <pre> | ||
scn SomeUDF | scn SomeUDF | ||
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</pre> | </pre> | ||
== | ==Examples== | ||
<pre> | |||
scn GetRandomForm | |||
; *** This script accepts a form list and returns one random form from it | |||
; local variables | |||
int iCount | |||
int iChoice | |||
ref RandomForm | |||
; arguments | |||
ref rFormList | |||
Begin Function { rFormList } | |||
let iCount := ListGetCount rFormList | |||
let iChoice := Rand 0, iCount | |||
let RandomForm := ListGetNthForm rFormList, iChoice | |||
SetFunctionValue RandomForm | |||
End | |||
</pre> | |||
<pre> | <pre> | ||
scn fnShuffle | scn fnShuffle | ||
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End | End | ||
</pre> | </pre> | ||
==Accepting any type arguments (advanced)== | |||
In some contexts, it is useful to allow arguments of any type for a UDF. Since [[Array Variable|array]] elements can be any type, this can be conveniently achieved using the [[NVSE Expressions]], <b>*</b> ('box') and <b>&</b> ('unbox'), and the [[TypeOf]] / [[GetType]] functions. | |||
<pre> | |||
scn MyUDF | |||
array_var AnyTypeArgument | |||
Begin Function { AnyTypeArgument } | |||
if eval (TypeOf *AnyTypeArgument) == "form" | |||
... | |||
End | |||
</pre> | |||
<pre> | |||
ref MyRef | |||
int MyInt | |||
call MyUDF &MyRef | |||
call MyUDF &MyInt | |||
</pre> | |||
==Notes== | ==Notes== | ||
*UDFs may be used recursively by saving the script once first without the sub call. | *UDFs may be used recursively by saving the script once first without the sub call. | ||
==See Also== | ==See Also== | ||