Candy from strangers

Friday 18 July 2003This is nearly 20 years old. Be careful.

When writing software these days, there are tons of tools the developer can use to help get his code done. These range from clever editors to samples to wizards. There are also many types of infrastructure that can be deployed as middleware to help while the code is running. These range from libraries to classic middleware to callable network services. Many of these tools and middleware are very helpful. Many really do speed up development by creating abstractions and raising the developer’s focus from the trivial to the insightful.

But you have to be careful: if the abstractions don’t match your needs, or there are flaws in the implementation, or something important is hidden from you, then they can be hindrances rather than helps.

Remember what you learned in kindergarten: never accept candy from strangers.

If you want to use a tool or a wizard to get some leverage over a thorny problem, make sure you know how the tool works. Not that you have to understand every line of code generated, or how the implementation really functions. But you need to understand what the wizard is good at, and what it is not. You have to know whether your problem really falls into the solution space of the tool. The tool is offering you something very tempting (an easy solution to your problem: that’s the candy). But you have to know the tool first (it can’t be a stranger to you).

I spent the better part of the past week struggling to use a rich and promising tool that turned out not to be the right solution for the problem I had. I’m still not sure whether it was fundamentally ill-suited to my situation, or if my misunderstanding of its foundations caused me to approach the solution badly, but either way, it was not a pleasant experience.

In the end, I scrapped the FFRT (fancy feature-rich technology) and cobbled something together myself in less than 100 lines of Python. It is low-tech, and won’t solve all sorts of problems that the FFRT will, but it’s perfect for what I need, and I couldn’t get the FFRT to work. Plus: I understand exactly how my code works.

This is similar to the advice in Tip 50 from The Pragmatic Programmer, “Don’t Use Wizard Code You Don’t Understand”. In the section entitled “Evil Wizards”, they acknowledge that this is an extreme position, and I don’t agree with the finality of their tip. I think wizards can be OK if they are shortcuts, but not if they are crutches.

Maybe this all boils down to Joel Spolsky’s Law of Leaky Abstractions. The tool is promising you an abstraction. If that abstraction is right for you and doesn’t leak in bad ways, the tool is good. If the abstraction is bad for you (maybe it hides something you want to see), or leaks in ways that hurt you, the tool is bad.

In any case, before you take the candy, make sure you know what it is and who is handing it to you.


Ah, is there any way you could elaborate on the tool you (mis)used? If it needs to be private, can you e-mail me?


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