Through the Interface

Cleaning up after yourself: how and when to dispose of AutoCAD objects in .NET

A question came up recently in an internal discussion and I thought I'd share it as it proved so illuminating. If I have an object of a type which implements IDisposable, is it good practice to explicitly dispose it (whether via the using statement or calling Dispose() explicitly)? The quick(ish) answer is: Yes it is, but sometimes you might choose not to as the increase in code simplicity outweighs the benefits derived from manually disposing of the objects. So, naturally, the devil is in the detail. Let's take a look at the three scenarios where you're likely to be... Read more →

Sectioning an AutoCAD solid using F#

In this earlier post we saw some C# code that creates 2D, 3D or "live" section geometry in AutoCAD 2007 or higher. I mentioned at the end of the post that I was curious to see how equivalent F# code compared with this C# source, especially in the area of array concatenation. Well, it turns out that there's still a little pain, just different pain (more like a sharp pain that's over quickly, rather than a dull, nagging ache :-). Here's the F# code: #light module SolidSection // Import managed assemblies #I @"C:\Program Files\Autodesk\AutoCAD 2009" #r "acdbmgd.dll" #r "acmgd.dll"... Read more →

Initialization code in your F# AutoCAD application

Back from a nice long weekend, although I spent most of it sick with a cold. I find this increasing... Read more →

A simple taxonomy of programming languages

Someone asked me recently how I categorize different programming paradigms. I thought it was a very interesting question, so here's what I responded. Please bear in mind that this is very much the way I see things, and is neither an exhaustive nor a formally-ratified taxonomy. One way to look at languages is whether they're declarative or imperative: Declarative programming languages map the way things are by building up “truths”: this category includes functional programming languages (such as Miranda, Haskell and Erlang) which tend to be mathematical in nature (you define equations) and start with lambda calculus as a... Read more →

Using AutoCAD 2009's new transient graphics API to show point clouds from F#

To start off my series of more in-depth looks at the new APIs provided in AutoCAD 2009, I decided to extend some recently posted F# code to generate and draw transient point clouds to be slightly less transient: we'll see how to use the new transient graphics API in AutoCAD to display a cache of transient graphics, even after the view has been changed. Some of you may be wondering about the amount of code I'm posting in F#. I find the technology extremely interesting and am also increasingly productive with it, so I've found myself gravitating towards using... Read more →

Recursive F# code to generate random point clouds inside AutoCAD

At the beginning of the week, we looked at some iterative F# code to generate random point clouds inside AutoCAD. We then took the time to use Reflector to dig under the hood and understand why the previous recursive implementation was causing stack problems. For completeness (and - I admit it - being driven slightly by laziness, as this is a quick post to crank out :-) here's the recursive version of the random point cloud generation code in F#: // Use lightweight F# syntax #light // Declare a specific namespace and module name module MyNamespaceRecursive.MyApplication // Import managed... Read more →

Using Reflector to diagnose tail call optimization in F#

I've talked about Lutz Roeder's Reflector tool a couple of times and it's proven to be very useful to me, once again. I mentioned in my last post about some problems I was having with tail recursion, and my choice to replace certain recursive functions with iterative versions. Today we're going to use Reflector to take a look under the hood of some compiled assemblies, to determine which recursive functions have been optimised correctly and which have not. Let's start by taking a look at the two recursive functions I mentioned last time, starting with the most simple: //... Read more →

Pointing at clouds: more random musings on AutoCAD and F#

On my way back from the US last week, I started thinking more about uses for random numbers inside AutoCAD: especially ones that allow me to try out some possible application areas for F#. There's something deliciously perverse about using random numbers in Engineering systems, where it's really important for outcomes to be deterministic (i.e. predictable) & precise. And that perversity appeals to me quite strongly, for some reason. Feel free to drop me a mail if you have an idea why that might be, any amateur psychologists out there... ;-) So, I got to thinking... an interesting domain... Read more →

Parallelizing robotic AutoCAD hatching with F# and .NET

In the last post we saw some code combining F# with C# to create a random "hatch" - a polyline path that bounces around within a boundary. This post extends the code to make use of Asynchronous Workflows in F# to parallelize the testing of points along a segment. In the initial design of the application I decided to test 10 points along each segment, to see whether it remained entirely within our boundary: the idea being that this granularity makes it very likely the segment will fail the test, should it happen to leave the boundary at any... Read more →

Robotic hatching inside AutoCAD using F# and .NET

I had too much fun with the last post just to let it drop: I decided to port the main command to F#, to show how it's possible to combine C# and F# inside a single project. The premise I started with was that the point-in-curve.cs library is something that we know works - and don't want to re-write - but would like to use from a new application we're developing in F#. This also gives us the chance to compare the performance between C# and F# when solving the same problem (although as we'll be calling through to... Read more →

Mardi Gras, Super Tuesday and F#

I'm in San Rafael today, at Autodesk's headquarters, to present F# at an internal meeting. I've just come in for a few days, so rather than adjusting to the Pacific timezone I'm settling for living on Eastern time: I get up at 4am (whether I like it or not ;-) and go to bed as early as I can in the evening. Which gives me some time to catch up on email and think about blog posts. It's a fun time to be in the US, on balance: I flew in (via New York, as it happens) just as... Read more →

Using F# to simulate hardware behaviour

This post has nothing whatsoever to do with Autodesk software: I just thought some of you might be interested in an old project I worked on during my University studies. I've already mentioned the project briefly in a couple of previous posts. So, after dusting off the 3.5 floppies I found in the attic, and working out how to extract the code from the gzipped tarballs they contained (thankfully WinZIP took care of that), I started the work to port the code from Miranda to F#. Miranda is still available for many OS platforms, although it has apparently largely... Read more →

Using F# Asynchronous Workflows to simplify concurrent programming in AutoCAD

In the last post we saw some code that downloaded data - serially - from a number of websites via RSS and created AutoCAD entities linking to the various posts. As promised, in today's post we take that code and enable it to query the same data in parallel by using Asynchronous Workflows in F#. Asynchronous Workflows are an easy-to-use yet powerful mechanism for enabling concurrent programming in F#. Firstly, a little background as to why this type of technique is important. As many - if not all - of you are aware, the days of raw processor speed... Read more →

Turning AutoCAD into an RSS reader with F#

OK, OK, you are probably thinking "why would anyone ever want to use AutoCAD as an RSS reader?". The answer is, of course, "they wouldn't". The point of the next few posts is not actually to enable AutoCAD to be used to read RSS, but to show how it is possible to use F# and .NET to extract information from RSS feeds and create corresponding AutoCAD entities. The reason I came onto this subject will also become more clear when you see my next post: I have been researching Asynchronous Workflows in F# - an uber-cool mechanism for managing... Read more →

Source now available for the .NET Framework 3.5

A quick post, for now, just to point you to this blog: http://blogs.msdn.com/sburke/archive/2008/01/16/configuring-visual-studio-to-debug-net-framework-source-code.aspx This will only work with Visual Studio 2008, it seems, so I haven't yet tested this out myself (I tend to be a laggard when it comes to Visual Studio, for some reason). A quick note on what I've been up to in my spare time: I'm currently diving deeply into F#, to prepare for some internal presentations I'll be giving in February. As part of the exercise I went up to the attic and dusted off the 3.5" floppies containing my old final year project... Read more →

Metaprogramming with AutoCAD - Part 3

In parts 1 & 2 of this series we looked at metaprogramming with AutoCAD using AutoLISP and VB(A), and then using VB.NET and C#. In this post we're going to look at what's possible from F#, through the lens of my relative inexperience with the language, of course. The quotations mechanism in F# appears to be the way to represent, analyse and execute program structure. This article describes the concepts, although it's quite deep and doesn't address the case that's most immediately interesting to AutoCAD develeopers: the ability to evaluate and execute code represented as a string. In fact,... Read more →

Getting the total volume of 3D solids in an AutoCAD model using F#

In one of my sessions at this year's AU, "There's More to .DWG Than AutoCAD®", I'll be showing some VB.NET code that goes through and collects information about solids, presenting it in a dialog along with the sum of the various volumes. You can get the code and the results from Part 1 of the session's handout. Just for fun, I thought I'd write some F# code to add the volumes of the 3D solid objects in the modelspace of the current drawing. I adopt a similar approach to the VB code - not caring about intersecting volumes, for... Read more →

More fun with F# and AutoCAD: string extraction and manipulation

I've been working through some draft chapters of Don Syme's Expert F# book (posted here, while the final version will be available in hardcover from early December). I'm definitely enjoying working with F#: the beauty of functional programming combined with the flexibility of .NET is a killer combination. Before I dive into the sample I put together for today's post, I thought I'd scribble down some musings on the language, to help position the technology in comparison with more popular imperative/object-oriented languages... Functional programming is great for deep mathematical problems, and so will play well with developers needing to... Read more →

A mathematical F# application integrating with AutoCAD via .NET

For my follow-up F# post I wanted to find something that showed off more of the capabilities of the F# language, while remaining something worth integrating with AutoCAD. The good news (at least as far as I'm concerned :-) is that one of the samples that ships with F# turned out to be perfect for this. The sample is known as "The Famous DirectX Demo", and is really, really cool. It uses F# to represent - extremely succinctly - a simulated, animated surface. And when I say succinct I mean it's tiny: with F# it's possible to represent complex... Read more →

My first F# application for AutoCAD

I couldn't resist... I just had to have a play with this technology, today. :-) Here are the steps to get your first (very simple) F# application working inside AutoCAD. First we need to download and install the latest F# distributable from here (at the time of writing this was the July 31 release - 1.9.2.9). We create a base F# project, selecting the "F# Project" template: We now add a new item to the project of type "F# Source File" to the project: The file created contains a lot of boilerplate code that is definitely worth looking at... Read more →