Click here to Skip to main content
Click here to Skip to main content
Technical Blog

Tagged as

Programming Language Misuse

, 30 Mar 2010 CC (ASA 2.5)
Rate this:
Please Sign up or sign in to vote.
I’m feeling a bit guilty about some code I wrote: using (new OperationTimer("MyOperation", this)){ // ... complete operation} This innocent looking C# snippet is hiding a tricky secret - the using statementis being misused (no pun intended).  The documentationdefines the int

I’m feeling a bit guilty about some code I wrote:

using (new OperationTimer("MyOperation", this))
{

    // ... complete operation
}

This innocent looking C# snippet is hiding a tricky secret - the using statement is being misused (no pun intended).  The documentation defines the intended usage clearly:

using Statement

  • Defines a scope, outside of which an object or objects will be disposed.

The problem?  The notion of “object disposal” is being hijacked!  In your garden variety IDisposable implementation, you’d be dealing with an external resource that needs to be released before the object can be removed from memory.  Instead, I’m using it to time a block of code like so:

class OperationTimer : IDisposable
{
    private readonly string _operationName;
    private readonly ITimable _obj;
    private readonly Stopwatch _stopwatch;

    public OperationWrapper(string operationName, ITimable obj)
    {
        _operationName = operationName;
        _obj = obj;
        _stopwatch = new Stopwatch();
        _stopwatch.Start();
    }

    public void Dispose()
    {
        _stopwatch.Stop();
        _obj.OnOperationCompleted(_operationName, _stopwatch.Elapsed);
    }
}

The constructor starts a timer and the Dispose() method stops it and reports the elapsed time.  (aside: if you’re interested in how I’m using the timer, check out my previous article Simplified Performance Counters) There are certainly other ways to accomplish this same behavior, but they lack the elegance of a neatly scoped code block.  It’s arguably an acceptable way to repurpose the language.  In fact, the ASP.NET MVC authors saw fit to use it in a similar fashion with the BeginForm helper.  The only “resource” it disposes of is to render a closing </form> tag.

My question is: When does repurposing language constructs turn from “acceptable language use” to a “dirty trick”, or worse, “illegible line noise”?

It seems like a slippery slope.  One instance that I don’t care for is controlling execution flow by-way-of logical operator precedence in most C-like languages:

expression1 && expression2 || expression3

Which is equivalent to:

if (expression1)
{
    if (!expression2)
    {
        expression3
    }
}
else
{
    expression3
} 

This takes advantage of the order of evaluation in a logical statement – it is assumed (correctly) that expression2 will never be evaluated if expression1 is evaluated as false, and instead, expression3 will get to run.  Likewise, if the first two evaluate to true, the truth value is known for the statement and expression3 is never evaluated. This is clearly not the intended usage which the language designers had in mind, but it works, and it saves any keywords from being written.

Some truly beautiful code has been written by way of hijacking the language.  For instance, here’s a program that will calculate the value of pi using an ascii circle.  Truly neat - but also completely useless from a software development standpoint.

What do you think?  Should I just get over my guilt about repurposing IDisposable?  Or, should I be true to the original intent of the language and find another way?

License

This article, along with any associated source code and files, is licensed under The Creative Commons Attribution-ShareAlike 2.5 License

Share

About the Author

James Kolpack
Software Developer (Senior)
United States United States
No Biography provided

Comments and Discussions

 
GeneralBoolean short circuiting is not misuse PinmemberLintMan6-Apr-10 4:59 
GeneralCorrection regarding: expression1 && expression2 || expression3 PinmemberMember 40016629-Mar-10 19:55 
GeneralRe: Correction regarding: expression1 && expression2 || expression3 PinmemberJames Kolpack30-Mar-10 18:58 
GeneralNot a "dirty trick" but a great technique that improves robustness: RAII! Pinmemberwtwhite29-Mar-10 18:16 
GeneralRe: Not a "dirty trick" but a great technique that improves robustness: RAII! Pinmembertorial31-Mar-10 10:07 
GeneralCaveats with "using" Pinmembersupercat925-Mar-10 5:45 
GeneralRe: Caveats with "using" Pinmemberwtwhite29-Mar-10 18:43 
GeneralRe: Caveats with "using" Pinmembersupercat931-Mar-10 8:27 
GeneralRe: Caveats with "using" Pinmemberwtwhite31-Mar-10 16:24 
GeneralRe: Caveats with "using" PinmemberIGood6-Apr-10 23:03 
GeneralSeems fine to me. Pinmemberdwilliss24-Mar-10 14:41 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

| Advertise | Privacy | Terms of Use | Mobile
Web02 | 2.8.1411023.1 | Last Updated 30 Mar 2010
Article Copyright 2010 by James Kolpack
Everything else Copyright © CodeProject, 1999-2014
Layout: fixed | fluid