Class 46: Program Mangagement

Held: Tuesday, 22 April 2003

Summary: Today we consider some key tools for program management, include separate compilation, make, and CVS.

Related Pages:

• EBoard.

Due

• Homework 6.

Notes:

• What did you think about Sorting Out Sorting? (I see from Erik's plan that his opinion has changed.)

Overview:

• Overview.
• Using Multiple Source Files.
• Make and Makefiles.
• CVS.

Introduction

• What do we care about when managing a program?
• That we can retrieve code we've accidentally deleted.
• That we can easily share our code with others.
• That the compiler can tell what needs to be done.
• ...

Building a Program from Multiple Source Files

• Rather than putting all of our source code into one file, it is often best to separate the different parts into different files.
• Why?
  • Fewer files to recompile upon change (yes, compilation was once a slow process).
  • Easier to give separate parts to different people.
  • May make logical sense to separate the program into parts.
  • Parts are easier to reuse.
  • ...
• In C, you can stop compilation at the "object code" stage by including -c in the command.
  • For example, gcc -c foo.c produces foo.o.
• Once you have a lot of .o files, you link them together with something like
  gcc -o program file1.o file2.o ... filen.o

Make and Makefiles

• As you start developing more sophisticated programs, you'll spend a lot of time trying to remember what needs to be done for different programs.
• For example, you may have a list of .o files that need to be put together for an executable.
• Similarly, you may need to turn a debugging flag on or off for all of your compilation.
• You may also have the problem of trying to remember what files you've changed since your last build.
• Make and its makefiles help solve all of these problems.
• We'll take a quick look at my standard makefile and some you might create.

CVS

• How do you successfully share lots of files with lots of people?
• How do you deal with different people potentially updating the same files?
• Traditionally with RCS, the revision control system (at least in the Unix world).
• More recently, with CVS, the concurrent versioning system.
• What do you need to know about CVS?
  • You can access CVS locally or over the Web.
  • Once you've "checked out" a project, it remembers where it came from.
• A simple first CVS session
  • Check out a project.
  • Modify files.
  • Confirm that your changes work.
  • Call cvs diff to compare your files to those in the repository
  • Call cvs commit to check in your changes
• A simple second CVS session
  • Call cvs update to incorporate changes your colleagues made.
  • Modify files.
  • Discover that you've made a new file to incorporate in the project. Use cvs add to add it.
  • Continue as before.
• To create a new project, use the following incredibly complex command from within the top-level directory of the project.

  cvs -d cvs-directory -m "comment" project vendor start
  

  • directory is the Unix directory which you are adding to the repository.
  • vendor is the person who "owns" the project. I use glimmer
• What can you put under CVS control?
  • Code files.
  • Makefiles
  • Documentation
  • HTML
  • ...