Circular dependency: why are these classes un-couplable

Question

I have a class, Thing, which has a number of variables. I also have a class, FileHandler, which records data to log files.

The FileHandler is specific to the instantiation of a Thing and needs to print several of the instance variables of Thing. So, Thing is imported into FileHandler.

There is another class, OtherThing, which also needs a Filehadler. Unfortunately, Thing imports OtherThing for reasons specific to the nature of Thing and OtherThing. This means that FileHandler imports Thing and Thing imports OtherThing which in turn imports FileHandler.

I can't seem to pull these apart. I will add more to this post depending on the comments. Is there an obvious reason that I cannot separate my classes here? It seems to be due to the fact that there is common data, that is needed by three classes.

Answer 1

Following this wording...

"All problems in computer science can be solved by another level of indirection... Except for the problem of too many layers of indirection." [David Wheeler]

...I would suggest to add an interface. Without knowing the exact code it's hard to decide. Maybe you try to introduce IThing or IFileHandler.