ADVANCED VISUAL BASIC 6 in Java

Print PDF417 in Java ADVANCED VISUAL BASIC 6
ADVANCED VISUAL BASIC 6
PDF417 Generation In Java
Using Barcode printer for Java Control to generate, create PDF417 image in Java applications.
4 The next day, you fix a bug in the new method and recompile the DLL 5 Your compiled EXE now fails with a Type mismatch error when it trys to retrieve the interface The step you missed here is that the new method wasn't found in the compatibility file, so VB regenerated a new IID each time you rebuilt the executable Note that depending on the number and type of edits you made between compiles, the IID might not change if you compile twice in the same IDE session You must copy the DLL that contains the new method as your compatibility file in order to lock down the IID The dilemma here is that the amount of baggage in the compatibility file and hence in your finished product grows every time you add a method Visual Basic requires all the extra information about old interface IIDs to make the DLL a binary replacement for the previous versions of the typelib VB uses the IID resources to provide marshaling support for all the previous interfaces, and uses the resources to enable the QueryInterface function to respond correctly to a request for a previous interface identifier To support marshaling on a legacy interface, VB replaces the Interface\{}\TypeLib key with an Interface\{ }\Forward key that points to the primary interface The Forward key instructs the typelib-driven marshaling engine to treat the interface the same as the currently implemented primary interface You get to carry all this compatibility information around in your finished product The resources get bigger and you add to registry overhead as you extend interfaces, the typelib grows as more and more aliases are added, and the data-driven QueryInterface implementation behind the publicly exposed objects has ever-more data to check before it can reply yes or no to an interface request Fortunately, any client compiled against a new version of the DLL won't be able to get the interface it expects from an old DLL and call a method that is not supported on the old version of the vtable Watching the changes that VB makes to a specific interface offers a lot of insights into the way VB lays out a typelib and the type of conditions against which it tries to protect you The following exercise looks at three versions of a simple class file I'll build a binary compatibility file against the first version, then modify the class by adding a function and then renaming the first function I'll
Bar Code Generator In Java
Using Barcode drawer for Java Control to generate, create bar code image in Java applications.
TYPE LIBRARIES AND VB
Barcode Scanner In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
ignore IID changes and look at three other fields The first relevant number is the vtable offset; the second is the DISPID, and the third is the order in which the function is listed in the typelib 'The starting class Public Function F1() As Long End Function Public Function F2() As Long End Function 'Add a function Public Function F1() As Long End Function
Printing PDF 417 In Visual C#
Using Barcode generator for .NET framework Control to generate, create PDF 417 image in VS .NET applications.
Table 154 Function F1 F2
Draw PDF417 In .NET
Using Barcode generation for ASP.NET Control to generate, create PDF 417 image in ASP.NET applications.
Function layout in the starting class VTable Offset 28 32 DISPID (hex) 60030000 60030001 Function Number 1 2
PDF-417 2d Barcode Generation In .NET
Using Barcode drawer for VS .NET Control to generate, create PDF417 image in VS .NET applications.
Table 155 Function F1 F2 F3
Create PDF-417 2d Barcode In Visual Basic .NET
Using Barcode encoder for .NET Control to generate, create PDF417 image in VS .NET applications.
Function layout with a compatible edit VTable Offset 28 32 36 DISPID (hex) 60030000 60030001 60030002 Function Number 1 3 2
EAN-13 Generation In Java
Using Barcode encoder for Java Control to generate, create EAN13 image in Java applications.
Table 156 Function F1Ex F2 F3
Generating Code128 In Java
Using Barcode encoder for Java Control to generate, create Code 128A image in Java applications.
Function layout with the compatibility broken VTable Offset 28 36 32 DISPID (hex) 60030003 60030005 60030004 Function Number 1 3 2
Bar Code Creation In Java
Using Barcode printer for Java Control to generate, create barcode image in Java applications.
ADVANCED VISUAL BASIC 6
Barcode Generation In Java
Using Barcode maker for Java Control to generate, create barcode image in Java applications.
Public Function F3() As Long End Function Public Function F2() As Long End Function
UPC Code Creator In Java
Using Barcode creator for Java Control to generate, create UPC-A Supplement 2 image in Java applications.
'Rename the first function, accepting the warning that you 'are breaking binary compatibility Public Function F2Ex() As Long End Function Public Function F3() As Long End Function Public Function F2() As Long End Function
Printing GTIN - 14 In Java
Using Barcode creation for Java Control to generate, create EAN - 14 image in Java applications.
There are several pieces of information you can glean from this data First, the function order in the typelib is always the same as the function order in the module Second, vtable order is based first on binary-compatibility function order and then on the function order in the CLS file Third, breaking compatibility can reorder the vtable (this is a corollary to the first and second observations) Fourth, VB goes out of its way to make sure that the DISPIDs in the new interface don't overlap the DISPID values in the binary-compatible interface This is done because both the old and the new versions have the same CLSID, and both support IDispatch binding You can make IDispatch calls on the interface without querying for the newly generated IID Generating new DISPIDs along with the new IID effectively blocks a call against the previous version of the interface Part of the problem with breaking binary compatibility is that all the information about previous interfaces is lost, not only for the broken interface, but also for the other interfaces in the project When compatibility is broken, the compatibility aliases are lost for all interfaces not just the one you broke The major version of the typelib is also incremented VB essentially reverts to project compatibility, preserving only the LIBID and CLSID values
Data Matrix 2d Barcode Printer In Visual C#
Using Barcode maker for Visual Studio .NET Control to generate, create DataMatrix image in .NET applications.
Development Compatibility Requirements The compatibility protection offered by VB is very strong, but you also need to consider how much is actually gained by changing the IID of an interface when
Generate UPC-A Supplement 5 In Visual Studio .NET
Using Barcode generation for VS .NET Control to generate, create UPC Symbol image in VS .NET applications.
Encoding EAN13 In .NET Framework
Using Barcode drawer for ASP.NET Control to generate, create GTIN - 13 image in ASP.NET applications.
Make ECC200 In Visual Basic .NET
Using Barcode generator for VS .NET Control to generate, create Data Matrix image in .NET framework applications.
Print Bar Code In .NET
Using Barcode generation for Visual Studio .NET Control to generate, create barcode image in Visual Studio .NET applications.