The Unix experience proves that using a handful of metaphors as the basis for a framework is a powerful strategy (recall the discussion of frameworks and shared context in Chapter13). The visual metaphor at the heart of modern GUIs (files represented by icons, and opened by clicking which invokes some designated handler program, typically able to create and edit these files) has proven both successful and long-lived, exerting a strong hold on users and interface designers ever since Xerox PARC pioneered it in the 1970s.

We quoted Brian Kernighan and Mike Lesk to similar effect in Chapter11. But the inquiry can't stop with indicting the GUI, because with all its flaws there is tremendous demand for GUIs from end users. Supposing we could get the metaphor right at the level of the design of user interactions, would Unix be capable of supporting it gracefully?

The answer is: probably not. We touched on this problem in considering whether the bag-of-bytes model is adequate. Macintosh-style file attributes may help provide the mechanism for richer support of GUIs, but it seems very unlikely that they are the whole answer. Unix's object model doesn't include the right fundamental constructs. We need to think through what a really strong framework for GUIs would be like — and, just as importantly, how it can be integrated with the existing frameworks of Unix. This is a hard problem, demanding fundamental insights that have yet to emerge from the noise and confusion of ordinary software engineering or academic research.