Conversion Mappings
As shown in the previous section, Automation types have a UNO counterpart according to the mapping tables. If a UNO function expects a particular type as an argument, then supply the corresponding Automation type. This is not always necessary as the bridge also accepts similar types. For example:
//UNO IDL void func( long value);
' VB Dim value As Byte value = 2 obj.func valLong
The following table shows the various Automation types, and how they are converted to UNO IDL types if the expected UNO IDL type has not been passed.
| Automation IDL Types (source) | UNO IDL Types (target) |
|---|---|
| boolean (true, false) unsigned char, short, long, float, double: 0 = false, > 0 = true
string: "true" = true, "false" = false |
boolean |
| boolean, unsigned char, short, long, float, double, string | byte |
| double, boolean, unsigned char, short, long, float, string | double |
| float, boolean, unsigned char, short, string | float |
| short, unsigned char, long, float, double, string | short |
| long, unsigned char, long, float, double, string | long |
| BSTR, boolean, unsigned char, short, long, float, double | string |
| short, boolean, unsigned char, long, float, double, string (1 character long) | char |
| long, boolean, unsigned char, short, float, double, string | enum |
When you use a string for a numeric value, it must contain an appropriate string representation of that value.
Floating point values are rounded if they are used for integer values.
Be careful using types that have a greater value space than the UNO type. Do not provide an argument that exceeds the value space which would result in an error. For example:
// UNO IDL void func([in] byte value);
' VB Dim value as Integer value= 1000 obj.func value 'causes an error
The conversion mappings only work with in parameters, that is, during calls from an Automation environment to a UNO function, as far as the UNO function takes in parameters.
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