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• Human sacrifice, dogs and cats living together, mass hysteria! and thread model errors!

  Reader Shaka comments on my post about error messages that "catastrophic failure" really does take the cake as being a terrible error message. I fondly remember the first time I saw "catastrophic failure" as an error message. I was an intern, running Read More... Posted Monday, May 07, 2007 4:22 PM by Eric Lippert | 1 Comments Filed under: Scripting, COM Programming, Threading

• Checking For Script Syntax Errors, This Time With Code

  A number of people asked me to clarify yesterday's entry. Rather than try to talk you through it, I think the code is straightforward enough to speak for itself. Here's a little skeleton that I just whipped up. #include <stdio.h> #include <activscp.h> Read More... Posted Wednesday, October 12, 2005 9:37 AM by Eric Lippert | 9 Comments Filed under: JScript, VBScript, Scripting, COM Programming

• Checking For Script Syntax Errors

  A reader asked me recently whether there was a way to check a chunk of JScript or VBScript for syntax errors without actually running the code. I'm sure that there are many third-party tools which you could find that do this. If you have your own script Read More... Posted Tuesday, October 11, 2005 10:35 AM by Eric Lippert | 7 Comments Filed under: JScript, VBScript, Scripting

• Local variables considered not very harmful

  Like I said, that code from last time was just test code, not real production code. Though clearly it works, I'd never write code like that in a million years. I'm not thrilled with the way it uses the answer variable of the outer scope as an accumulator, Read More... Posted Tuesday, October 04, 2005 10:22 AM by Eric Lippert | 5 Comments Filed under: JScript, Scripting

• Guru meditations on scope chains of closures

  I just had a really interesting meeting with some of the scripting community MVPs. I may write up some notes on that meeting here next week, so watch this space. In other news, someone asked me last night (and I quote) Oh ECMA guru, can you provide a Read More... Posted Friday, September 30, 2005 12:41 PM by Eric Lippert | 11 Comments Filed under: JScript, Scripting

• Implementing Event Handling, Part Two

  It's been an insanely busy month for me, between having multiple out-of-town guests, throwing a party for the people who couldn't make it to the wedding, and oh yeah, getting up to speed on the C# compiler and trying to understand the implications that Read More... Posted Wednesday, September 21, 2005 11:51 AM by Eric Lippert | 2 Comments Filed under: JScript, VBScript, Scripting, COM Programming

• Implementing Event Handling, Part One

  Back in February I posted a bit about how script hosts such as Windows Script Host dynamically hook up event sources (objects) to event sinks (chunks of script that run when the event fires.) It has become apparent from some questions I've received recently Read More... Posted Friday, September 09, 2005 3:35 PM by Eric Lippert | 0 Comments Filed under: Scripting, COM Programming

• 250% of what, exactly?

  I just got a question this morning about how to take two collections of items and determine how many of those items had the same name. The user had written this straightforward but extremely slow VBScript algorithm: For Each Frog In Frogs For Each Toad Read More... Posted Thursday, September 01, 2005 10:13 AM by Eric Lippert | 27 Comments Filed under: VBScript, Scripting, Performance

• VBScript Default Property Semantics

  Here’s a question I recently got about VBScript, where by "recently" I mean August 28th, 2003. This code works just fine: Set myObject = CreateObject("myObject") myObject.myName = "Eric" WScript.Echo myObject ' myName is the default property, so prints Read More... Posted Tuesday, August 30, 2005 10:15 AM by Eric Lippert | 9 Comments Filed under: VBScript, Scripting, COM Programming

• Recursion, Part Six: Making CPS Work

  JScript doesn't support CPS natively but we can write another dispatch engine that makes it work. There's only ever one active continuation, so lets have a new rule: JScript CPS functions are allowed to return, but the last thing that they do must be Read More... Posted Monday, August 15, 2005 3:00 AM by Eric Lippert | 2 Comments Filed under: JScript, Scripting, Rarefied Heights, Recursion, Continuation Passing Style

• Recursion, Part Five: More on CPS

  Suppose we wanted to write this by-now-familiar little function in continuation passing style: function treeDepth(curtree) { if (curtree == null) return 0; else { var leftDepth = treeDepth(curtree.left); var rightDepth = treeDepth(curtree.right); return Read More... Posted Thursday, August 11, 2005 3:00 AM by Eric Lippert | 0 Comments Filed under: JScript, Scripting, Rarefied Heights, Recursion, Continuation Passing Style

• Recursion, Part Four: Continuation Passing Style

  We're getting hung up on the stack management aspects of recursive programming. Why do we need a stack at all? What purpose does it serve? If you're like most developers, you probably learned about subroutines and functions at an early age. The idea is Read More... Posted Monday, August 08, 2005 3:00 AM by Eric Lippert | 3 Comments Filed under: JScript, Scripting, Rarefied Heights, Recursion, Continuation Passing Style

• Recursion, Part Three: Building a Dispatch Engine

  There's a particular technique that I like to use to solve problems -- it doesn't always work, but when it does, it can produce programs of surprising elegance and power. The technique is this: if you have a specific problem to solve, solve a more general Read More... Posted Thursday, August 04, 2005 3:00 AM by Eric Lippert | 0 Comments Filed under: JScript, Scripting, Rarefied Heights, Recursion

• Recursion, Part Two: Unrolling a Recursive Function With an Explicit Stack

  That recursive solution is pretty cool, to be sure. But there is one big problem with it. Consider this Jscript program that puts a few more nodes into our tree from last time: function tree(value, left, right) { this.value = value; this.left = left; Read More... Posted Monday, August 01, 2005 3:00 AM by Eric Lippert | 3 Comments Filed under: JScript, Scripting, Rarefied Heights, Recursion

• Recursion, Part One: Recursive Data Structures and Functions

  The first thing to wrap your head around is recursively defined data structures. Let's start with something simple. Think about the abstract idea of “list”. Most people think of a “list” as an ordered collection of “items”, one after the other, with a Read More... Posted Wednesday, July 27, 2005 3:00 AM by Eric Lippert | 7 Comments Filed under: JScript, Scripting, Rarefied Heights, Recursion