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s2sh2: The Other s2 Shell

See also: s2sh.md

s2sh2

s2sh2 is a standalone overhaul and cleanup of the venerable s2sh, started in early February, 2020. It provides essentially the same functionality - a front-end into the s2 scripting engine - but with the following notable (or at least mentionable) differences:

• First and foremost, the way it processes command-line options has been rewritten from scratch, using a highly over-engineered argument parsing system which provides more conventional/flexible CLI arg handling. The names of the flags vary wildly from s2sh's, which is s2sh2's primary incompatibility with its predecessor. (Their functionality is identical, though.)

• The help system is more friendly, breaking the options into "tiers" to avoid overwhelming the user¹ with Too Much Info.

• The S2 user-defined keyword (with a capital S) refers to the same object as the historical s2 (lower-case) global variable, but resolves more quickly than the latter. Unfortunately, exposing the historical s2 symbol this way would break a great many scripts which create same-named scope-local aliases to it as a lookup speed optimization.

• Loadable modules built statically into s2sh have historically been installed directly into the s2 object using their module's name. Groups of related modules may now get installed into their own namespace. e.g. s2.regex_posix and s2.regex_js are now installed as s2.regex.posix resp. s2.regex.js, without retaining their historical names.

• s2.ARGV gets fully populated regardless of whether or not any script-side flags are passed in to the app. Practice has shown that the predecessor's behaviour of only populating it when there are flags, while technically better, is a pain in the backside in client scripts. ("The road to hell," and all that.)

As of this writing (2020-02-03), the shells are, aside from the differences listed above, functionally compatible. See the s2sh docs for much more information about these shells, e.g. how to statically link in loadable modules or extend s2sh[2] using client-side C code.

Footnotes

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1. ^{^} That'd be me.