How to get scons to treat a directory itself as a target?

Question

I'm trying to set up a build involving an external tool which produces a directory as output (doxyindexer for the curious). So far, I've essentially got these commands:

target = "doxysearch.db/iamchert"
doxygen.Doxyindexer(target,["project1.xml","project2.xml","project3.xml"])
Default([target])
Default(Install(ARGUMENTS["cgibin"],"doxysearch.db"))

The problem that I'm having is that I think I'd like target to be the directory itself, not some random file inside the directory. There's nothing I can glob because the target doesn't exist until I build it and I don't want to presume anything that Dimitri might change! When I use the directory as the target, I get this error:

TypeError: Tried to lookup Dir 'doxysearch.db' as a File.:

which is why I picked iamchert to be the target. Those lines all seem to work as expected, even if my approach is a hack. However, I can't get that last line to work. I need to copy the directory doxysearch.db into the cgi-bin directory, which is specified on the command line by the user. Maybe someone can explain how to do this step properly? I'm a newb when it comes to scons!

I'm having trouble googling the answer because all the search words involved are too common to find me specific help!

Answer 1

SCons does in fact treat all the files in a dir as dependencies of that dir. There are some dark corners that need work, but it should work in a simple case like this.

What you need is the undocumented target_factory builder flag. When you define Doxyindexer do it like this:

doxyindexer = Builder(..., target_factory=env.fs.Dir)

and have your builder return the dir itself. That should avoid the TypeError you were getting.

Answer 2

Im not sure how well SCons will work with the target being a directory. The issue is: How should SCons determine if the directory has changed or not to know if it should be built? The obvious answer would be that a directory is considered to be changed if it has more or less files therein, but I dont think SCons currently does this check and you might have to make your own builder to get it.

I did the following example to test this, and it never builds:

env = Environment()
env.Command(target = 'targetDir',
            source = 'srcTextFile',
            action = Copy("$TARGET", "$SOURCE"))

When I execute SCons, I always get the same result:

scons: '.' is up to date

Regarding your SCons code, I think it would work better as follows:

targetDir = "doxysearch.db/iamchert"
srcFiles = ["project1.xml","project2.xml","project3.xml"]

doxygenTarget = doxygen.Doxyindexer(targetDir, srcFiles)

    # This may need to be called via the Command() builder like this:
    # cmd = "doxygen.Doxyindexer("$TARGET", "$SOURCE")
    # doxygenTarget = env.Command(target=targetDir, source=srcFiles, action=cmd)

# This call to Default isnt really necessary
Default(doxygenTarget)
Install(ARGUMENTS["cgibin"], doxygenTarget)