GSoC/GCI Archive
Google Code-in 2014 BRL-CAD

Eliminate any library global variable

completed by: Andromeda Galaxy

mentors: Hardeep Singh Rai, Mihai Neacsu

BRL-CAD is a very large mature code base and as with such body of code, issues creep in over time that are undesirable. One such issue is the introduction of global variables. They are often a short-term crutch that allows some feature to be implemented quickly, but they become a long-term burden.

All you need to do is eliminate any one of them that is declared in a header and accessed in more than one file. That means static globals don't count and variables declared global in one file but not used anywhere else also don't count. That said, we try to make it clear where our shared globals are at by putting their definitions in one place (see references below).

You also must preserve the behavior and capabilities of code that was using the global and remove the variable cleanly. That is to say, for example, that if there was a global variable storing a date string that is printed, you can't just eliminate the variable and remove the line that printed the variable -- you'd probably replace the code printing the date with a function or pass the date in from calling code.

This task is to eliminate just ONE global variable in any of our libraries. If you're quick and clever, you'll notice that some globals are VERY simple to eliminate while others can be complicated with thousands of lines of code needing to get updated.

Submit a patch file

  • src/libbu/globals.c
  • src/libbn/globals.c
  • src/librt/globals.c
  • What you'll have to modify completely depends on how you're going to remove the global.