Class 34: Make, Revisited

Held: Tuesday, 5 April 2011

Summary: We consider more details of make, a useful tool for automating lots of stuff.

Related Pages:

• EBoard.
• Reading: Managing Projects with GNU Make, Chapters 1 and 2 .

Notes:

• Responses to your questions on the make reading have been posted. We will also talk about them in class.
• Missing questions from AA, DG, MH, JJ, SR, MT.
• Why do I give you complex and hard to parse readings? Because I think you need to develop the skills to read complex technical things (rather than pre-processed pablum), even if you won't be CS majors.
• Reading for tomorrow: K&R 5.5, B3.
• Reading for Friday: Debugging with DDD.
• Update on Kington presentation.
• EC for Wednesday's M.C. Escher talk [academic]
• EC for Thursday's nonvo on Iowa Water (or other part of that symposium) [academic]
• EC for Friday's presentation of Sita Sings the Blues [academic]
• EC for today's talks on Alt-Break.
• EC for any activity in the animation festival, including Tiny Circus [peer]
• EC for either part of the baseball doubleheader against Knox [peer]

Overview:

• About Make.
• File Suffixes.
• Your Questions.
• A Collaborative Makefile.

Make

• Purpose: Make it easier to build projects, particularly complex multi-part projects.
• We'll look at two sample projects:
  • The course Web site (or portions thereof)
  • A recent program you worked on (or my version thereof)
• Model: A collection of targets
  • Each target is something that we might want to build (or a placeholder to help us build stuff)
  • There are instructions for building each target.
• Typical targets:
  • default: The default thing or things to build (e.g., the application or library)
  • test or check: Instructions for testing the main thing. (Generally predicated on building default first.)
  • install: Install the things we've just built.
  • clean: Remove intermediate files (such as .o files).
  • distclean: Remove everything but the source files.
  • package: Put everything together into a tarball.
• Two kinds of targets
  • File targets: Things we actually build
  • Command targets: A shorthand for something we want to do, even if it might not build any files. (clean and test are examples) These are also called phony targets.
• Variables: Making it easier. Four kinds:
  • Your variables
  • Standard variables you set
  • Variables from the standard rules
  • Automatic variables
• Your variables

  NAME = VALUES
  

• Standard variables you set
  • CFLAGS
  • LDFLAGS
  • LDLIBS
• Variables from the standard rules
  • $(CC)
  • $(COMPILE.c)
  • ...
• Automatic variables
  • $@ - The target
  • $< - The first prereq
  • $? - Newer prereqs
  • $^ - All prereqs
  • $* - The stem of the target

File Suffixes

• In Unix/Linux, as in many operating systems, we give a hint to the contents of a file by adding a suffix.
• You already know some suffixes: .c, .o, and .h.
• Some other useful ones
  • .a - an archive/library
  • .s - assembly code
  • .sh - a shell script (collection of shell commands)
• Some other ones mentioned in the text but that you're unlikely to use
  • .l - Lex/Flex source code
  • .so - a shared object (like a DLL)

Your Questions

• See the separate reading page.
• Some possible demonstrations:
  • Libraries
  • VPATH and vpath
  • CPPFLAGS
  • .PRECIOUS
  • .PHONY

Exercise

• We'll work together to build a nice Makefile for my files from problem 3 on the exam.