Cva_Copy
Macro to initialize variadic argument list object variable from an already initialized variadic argument list object variable
Syntax
`
Cva_Copy( dst_list, src_list )
`
Parameters
`dst_list`
destination `Cva_List` variable to initialize
`src_list`
source `Cva_List` variable to copy from
Description
Copies one `Cva_List` type variable to another `Cva_List` type variable. `dst_list` is initialized using current state of `src_list`
`src_list` must already have been initialized with a previous `Cva_Start` or `Cva_Copy` statement.
`Cva_Copy` is like a copy constructor for the a variadic argument list object and must eventually have a matching call to `Cva_End`, which is like the destructor. After `Cva_End` for `dst_list` has been called, `dst_list` can be reused and reinitialized with another call to `Cva_Start` or `Cva_Copy`. The `Cva_Copy` and `Cva_End` calls must both be called in the same procedure (for cross platform compatibility).
Example
`
'' example of using cva_copy to create
'' a copy of the variable argument list
Sub proc cdecl(count As Integer, ... )
Dim args1 As Cva_List
Dim args2 As Cva_List
'' first list
Cva_Start( args1, count )
'' create a copy
Cva_Copy( args2, args1 )
For i As Integer = 1 To count
Print Cva_Arg( args1, Integer ), Cva_Arg( args2, Integer )
Next
'' clean-up
Cva_End( args2 )
Cva_End( args1 )
End Sub
proc( 4, 4000, 300, 20, 1 )
`
`
'' example of using cva_copy to create
'' a copy of the variable argument list
'' and pass it to another procedure
Sub vproc cdecl(count As Integer, ByRef args As Cva_List )
'' if we don't know that caller made a copy
'' of args, it is safe to make our own copy
'' and leave the passed in args untouched
Dim a As Cva_List
Cva_Copy( a, args )
Print "vproc"
For i As Integer = 1 To count
Print Cva_Arg( a, Integer )
Next
'' clean-up
Cva_End( a )
End Sub
Sub proc cdecl(count As Integer, ... )
Dim args As Cva_List
Cva_Start( args, count )
'' if don't know that the called procedure
'' will make it's own copy, it is safe to
'' make a copy here and pass that instead
Dim tmp As Cva_List
Cva_Copy( tmp, args )
vproc( count, tmp )
Cva_End( tmp )
'' args is still valid, we can use it
Print "proc"
For i As Integer = 1 To count
Print Cva_Arg( args, Integer )
Next
'' clean-up
Cva_End( args )
End Sub
proc( 4, 4000, 300, 20, 1 )
`
Dialect Differences

- Not available in the -lang qb dialect unless referenced with the alias `__cva_copy`.

Differences from QB

- New to FreeBASIC

See also

- ... (Ellipsis)
- `Cva_Arg`
- `Cva_End`
- `Cva_List`
- `Cva_Start`