Efficient linking

Eljay Love-Jensen eljay@adobe.com
Fri Sep 12 12:42:00 GMT 2003


Hi Starling,

I think you should read this book, "Large-Scale C++ Software Design" by Lakos.

And you should also be concerned about having good makefiles, as per this PDF essay "Recursive Make Considered Harmful" by Miller.  URL: <http://www.tip.net.au/~millerp/rmch/recu-make-cons-harm.html>.

My own rules of thumb:
+ Every header file should include ONLY the header files that they need.
+ Every source file should include ONLY the header files that they need.
+ No header/source file should depend upon a needed header file being included by another header file.  After all, someone may change a header's included header to a forward declaration (which I also shy away from).
+ Every header file should be "complete", such that they are stand-alone compileable.
+ No (or very few) "uber header files" that includes all header files.
+ No reliance upon PCH to include everything and the kitchen sink.  Very bad practice, in my opinion.
+ Use generated dependencies in your makefiles.
+ Use make fragments, which are all make-included into a whole.  (Assuming you use GNU make.)
+ No recursive builds.  (Presuming the individual builds otherwise have interdependencies.)

These rules mean that you won't "build too much" (waste of time), nor "build too little" (untrustworthy builds, unless done from a clean slate).  And you should be able to take advantage of multi CPUs for concurrent builds.

--Eljay




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