TwinBasicSevenZip

7-Zip COM library compatible for use in VBA (32-bit and 64-bit), VB6 and twinBASIC

This is a proof of concept to demonstrate the capabilities of twinBASIC both as a COM consumer and producer. Traditionally, VB6/VBA solutions can only work with Automation-compatible libraries. To work with non-Automation COM libraries requires use of additional tools or hacks to work around the limitations. 7-Zip DLL was chosen to demonstrate that twinBASIC is capable of natively authoring a solution that can take the COM-like interfaces from 7-Zip's DLLs and work with it and then expose it as an Automation-compatible object or even as a simple Declare statement.

This is a very rough and there is much to tap. The error handling is minimal and the testing coverage need to be better.

Sample Usage

There are two ways to use the DLL:

1. As a Declare statement:

This bypass the need to register the DLL and use the COM objects, allowing you to directly extract a supported archive format into a directory of your choosing. The sample VBA/VB6 compatible code follows:

Private Declare PtrSafe Sub Extract Lib "C:\Temp\SevenZipArchive_win64.dll" (ArchivePath As LongPtr, DestinationFolder As LongPtr)

Public Sub DemoDeclare()
    Extract StrPtr("C:\Temp\Test.7z"), StrPtr("C:\Temp\Test7z_Extract")
End Sub

This requires placing one of 7-Zip's DLL in the same folder as the SevenZipArchive_winXX.dll in order for the twinBASIC DLL to work. You can use 7z.dll, 7za.dll or 7zxa.dll depending on your requirements. For example, if you want to unzip .7z file, then any those DLL will work. However, if you want to unzip using .zip files, you must use 7z.dll.

2. As a COM objects:

You can register the library using regsvr32.exe (keeping in mind to use the appropriate regsvr32.exe to match the bitness) and then reference the library from your VBx project.

The ArchiveFactory allow you to specify where to locate the 7-Zip's DLL files (which can be one of 7z.dll, 7za.dll or 7zxa.dll) If it's not specified explicitly, it defaults to the same folder as the SevenZipArchive_winXX.dll preferring to load the DLL in the given order. You can then create an ArchiveExtracotr from the factory as shown:

Public Sub DemoCom()
    SevenZipArchive.ArchiveFactory.ArchiveLibPath = "C:\Program Files\7-Zip\7z.dll"
    
    Dim ae As SevenZipArchive.ArchiveExtractor
    Set ae = SevenZipArchive.ArchiveFactory.CreateArchiveExtractor("C:\Temp\Test.7z")
    
    ae.Extract "C:\Temp\Test7z_Com"
End Sub

TODOs:

As this is in alpha, there are few numbers of features that are possible but not implemented:

• Implement the compress routine
• Handle subfolders within archive files and preserving various file attributes (e.g. timestamps)
• Provide a progress dialog
• Provide a event to allow the consuming VBx/tB code to respond to each file being extracted/compressed
• Provide more control over the format supported (currently it depends on the file extension but there are other ways such as looking for an unique signature within the file)
• Update the keywords that are planned to be replaced (see: twinbasic/twinbasic#806 )
• Tests, tests, tests!

Contributing & Building

To build, you must have twinBASIC compiler. You can obtain the latest from here: twinbasic/twinbasic#772

You can then import the source code contained in the Twinbasic folder using command like this:

...\bin\twinBASIC_win64.exe" import .\SevenZipArchive.twinproj .\Source --overwrite

For more details, refer to the wiki.