Repository files navigation

NodeTcl is a native Node extension that embeds a Tcl interpreter within the Node.js environment, allowing you to invoke Tcl commands from within JavaScript code.

This is especially useful for leveraging existing Tcl code or packages in a new Node.js application.

Just runmake and a shared-library namednodetcl.node will be created.

Compilation has only been tested on FreeBSD 8.2 with node-0.4.12 and tcl-8.5.10.

Included is anexample1.js which contains the following:

vartcl=require('./nodetcl.node');varinterp=newtcl.NodeTcl();console.log(interp.eval("expr 6*7"));

Once you have built the extension, you can run it with:

  node example1.js

Which will print simply:

42

• eval(string) executes a string containing one or more Tcl commands, returning the result.
• call(command, ...) executes a single Tcl command with explicit arguments, returning the result.
• proc(name, body) declares a new Tcl command that invokes the specified JavaScript function body.
• getStacktrace() returns Tcl's stacktrace of the last error that occured.
• setTimeLimit(seconds) sets a time limit (in seconds) for all subsequent 'call' or 'eval' calls, a limit of 0 disables this.
• getTimeLimit() returns the current time limit setting.
• makeSafe() converts the interpreter into a safe interpreter.
• deleteProc(name) removes a proc from the interpreter (also works on default procs, such asexit).
• process_events(allEvents) allows pending Tcl events to be processed. If the argument is false, only one pending event will be processed.

Thecall method differs fromeval in that the arguments are not evaluated (no need to escape special characters). It takes an arbitrary amount of arguments and executes them as a Tcl statement:

interp.call("puts","[hello world]")

Which will return:

[helloworld]

call also accepts JavaScript arrays (will be converted to Tcl lists) and simple key-value-mapping objects (will be converted to Tcl dicts) as arguments:

interp.call("llength",[1,2,3,4,5])

Which will return:

5

eval andcall both convert their Tcl return values to JavaScript data types: lists become arrays, dicts become objects, and numbers are returned as numbers.

Return values from custom procs can also have different types, just like call's arguments:

interp.proc("foo",function(){return["foo","bar"]})

• The Tcl event loop is not automatically invoked aftereval orcall returns, so any Tcl timers or events will not be triggered. To keep the Tcl event loop alive in an asyncronous Node-compatible style, you must periodically invokeinterp.process_events(). See the includedexample3.js for an example of how to do this.