Porting notes

Things to watch out for

• The mapping of the vba constants is different. Take for example the xlGuess constant, in VBA it's fully qualified name is Excel.XlYesNoGuess.xlGuess, in the helperapi it's com.sun.star.helper.constant.XlYesNoGuess.xlGuess and in oovbaapi it's org.openoffice.excel.XlYesNoGuess.xlGuess
• All objects in the helperapi extend HelperInterfaceAdaptor, nothing similar (yet) exists in oovbaapi so this can be ignored in the implementation
• There are a quite few helper classes in the helperapi project e.g. RangeHelper.java they shouldn't be confused with the actual implementation objects we wish to port.
• classes and idl files of the same name can exist in multiple namespaces and this can be confusing. Because the helperapi was written with both the word and excel api(s) in mind there can be classes that share a common implementation and interfaces e.g.
  • com/sun/star/helper/calc/XShape.idl
  • com/sun/star/helper/common/XShape.idl
  • com/sun/star/helper/writer/XShape.idl
• Collections, these are handled differently see implementing a vba Collection in oovbaapi
• Every helperapi idl method defines BasicErrorException which allows and api method to transfer an error code and associated string paramater to basic.

Hints for porting idl

Objects with Default Properties

This is something not handled by the helperapi but something you should be aware of when implementing a vba compatibility object. What is a default property, an example probably explains the concept better.

Range("a1") = "text"

is a short cut for

Range("a1").Value = "text"

Value is a default property in the example above. We can provide similar behavior in basic with a compatibility api object ensuring the object implements XDefaultProperty.idl

Objects with Default Method

Similar to above some vba objects have a default method e.g. the Collection object

set col = Sheets
msgbox col(1).Name

is a short cut for

set col = Sheets
msgbox col.Item(1).Name

Item is a default method in the example above. We can provide similar behavior in basic with a compatibility api object ensuring the object implements XDefaultMethod.idl

Porting Collection objects

Generally all collection objects have a Count and an Item method and additionally the behaviour mentioned above. Also Collection objects can be used in a For Each loop. To cater for that a helper implementation object can also be used that provides for the necessary support. A example of a ported Collection object can be found in the Porting example section