Why is the code in most STL implementations so convoluted?

Question

The STL is a critical piece of the C++ world, most implementations derive from the initial efforts by Stepanov and Musser.

My question is given the criticality of the co

Answer 1

Neil Butterworth, now listed as "anon", provided a useful link in his answer to the SO question "Is there a readable implementation of the STL?". Quoting his answer there:

There is a book The C++ Standard Template Library, co-authored by the original STL designers Stepanov & Lee (together with P.J. Plauger and David Musser), which describes a possible implementation, complete with code - see http://www.amazon.co.uk/C-Standard-Template-Library/dp/0134376331.

See also the other answers in that thread.

Anyway, most of the STL code (by STL I here mean the STL-like subset of the C++ standard library) is template code, and as such must be header-only, and since it's used in almost every program it pays to have that code as short as possible.

Thus, the natural trade-off point between conciseness and readability is much farther over on the conciseness end of the scale than with "normal" code.

In addition, the standard library is where the system-independent view of application code is connected to the underlying system, utilizing all kinds of compiler-specific things that you as an application developer should best stay away from.