Tracking hard or symbolic links with mercurial on Windows

Question

In a rather large project, I would like to put the same file (or folder) in different locations. When it is changed in one location, the changes should be propagated. In Subversion, I could use externals to achieve this behavior.

I tried to solve this by using hard links and symbolic links, but Mercurial seems to not track any of them. Instead, it commits the content of the files to its repository instead of the link property. When I clone the repository, the information is lost.

Is this a Windows-specific behavior of Mercurial or can't it track links at all? Is there another way to track a file that is accessible from different locations in Mercurial?

Answer 1

Mercurial can track symbolic links, but they look strange when checked out on Windows. What happens is that Mercurial creates a file with the link target as the file content. There is unfortunately no support for creating real symbolic links on Windows systems that support them, such as Windows Vista. The result of this is that you cannot use symbolic links in a repository that is supposed to be portable between both systems. Please see the discussion in Issue1825 for more on this feature.

The closest match for svn:externals is Mercurial subrepositories. Depending on how you used svn:externals, subrepos may or may not be what you want. Please see my answer to another question about subrepos for some advice. I wrote part of the code for subrepos and off the top of my head, I think mounting a subrepo several times in the same main repository sounds like a recipe for confusion. But maybe you can make it work — just be aware that subrepos are a tricky part of Mercurial.