undefined | Better HN

0 pointsle-mark8y ago0 comments

TCL is pretty old school and doesn't get a lot of attention nowadays. The main use I'm aware of is in BigIP F5 config files. There are some really interesting things about it though, for example how control flow constructs (if/else, while) are implemented as commands, using built in uplevel and upvar[1] commands to control the scope of the currently executing code. Some people say it's lisp-like, that's one of the things they mean.

TCL has an interesting history, it's creator is also known for Ousthout's Dichotomy[2] which is useful when disambiguating between "scripting" and "other" languages (an argument that occurs frequently on the internet).

Antirez has written about TCL, if you're an admirer of him or his work (redis) you may find his take on it interesting[3].

[1] https://en.wikipedia.org/wiki/Tcl#Uplevel

[2] https://en.wikipedia.org/wiki/Ousterhout%27s_dichotomy

[3] http://antirez.com/articoli/tclmisunderstood.html

0 comments

2 comments · 2 top-level

cchase888y ago

I wrote a blog post where I show how to define "until" using Uplevel: http://christopherchase.cc/posts/tcl-until.html

fundabulousrIII8y ago

upvar and uplevel are also the only parts of the language that I do not use in production scripting. They have their place. It is not in end user space.

j / k navigate · click thread line to collapse