WinCOMClient.jl

A lightweight, native Windows COM Automation client for Julia. It calls ole32 and oleaut32 directly and does not depend on Python.

Status: Early development. The package supports dynamic IDispatch clients but does not implement COM event callbacks.

Requirements

• Windows x64
• Julia 1.10 or later
• A COM Automation server to control

Installation

using Pkg
Pkg.add("WinCOMClient")

Until the first registry release becomes available, install directly from GitHub:

Pkg.add(url="https://github.com/prestalab/WinCOMClient.jl.git")

For local development:

using Pkg
Pkg.develop(path=raw"C:\projects\WinCOMClient.jl")

Usage

using WinCOMClient

excel = Dispatch("Excel.Application")
try
    excel.Visible = true
    workbook = excel.Workbooks().Add()
    sheet = workbook.Worksheets(1)
    sheet.Range("A1").Value = "Hello from Julia"
finally
    excel.Quit()
    close(excel)
end

Members are resolved lazily. Call a property with no arguments to read it:

version = excel.Version()

Collections support indexing, length, and iteration when exposed by the COM server:

for drive in Dispatch("Scripting.FileSystemObject").Drives()
    println(drive.DriveLetter())
end

Use close(object) for deterministic release of an owned IDispatch reference. A finalizer provides fallback cleanup.

API

• Dispatch(progid_or_clsid) creates or attaches to a COM object.
• DispatchEx(clsid) creates a local COM object; remote DCOM is not supported.
• GetActiveObject(class) attaches to a running object.
• GetObject(pathname=...) and Moniker(path) bind through a COM moniker.
• value(member) performs an explicit property read.
• close(object) releases the owned COM reference.

Limitations

• Functionality requires Windows x64. On other platforms the package still imports (required by registry CI, which runs on Linux), but every COM entry point throws a WinCOMClient.jl supports Windows only error.
• COM callbacks and connection points are not implemented.
• Remote DCOM is not implemented.
• SAFEARRAY support is currently limited to one and two dimensions.
• COM initialization is process-oriented; applications needing strict apartment control should initialize COM before loading the package.

Development

Run the test suite with:

using Pkg
Pkg.test()

The integration tests use Scripting.FileSystemObject; Excel tests run only when Excel is installed.

License

WinCOMClient.jl is available under the MIT License. See LICENSE.