Why Duck Typing Is Safe
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Jun 16, 2020
Programming

For the last 20 years I've been programming almost exclusively in languages with either duck typing or structural typing. These are languages where you can have objects that either conform to an informal interface without that conformance being declared (dynamically-typed languages), or where conformance is simply a matter of matching the interface (Go). This is as opposed to languages where conformance must be explicitly declared somehow, either with a formal subclass relationship (the class-based portion of C++) or by explicitly declaring conformance to an interface (Java).

Not needing to formally declare conformance is powerful because you can take some pre-existing object, declare a new interface that it conforms to, and then use it with your interface. This reduces the endless paperwork around re-wrapping things to make existing objects conform to new interfaces.

I have seen a lot of programmers over the years express concerns; what if something accidentally conforms to an interface and causes some horrible bug? What if I have an interface for Shoot() for a video game and some object wanders in that Shoot()s a real gun by accident? Isn't it safer to formally declare conformance?

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XML Namespaces in a Nutshell
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Aug 05, 2016
Programming

I've said several times that XML Namespaces are simple, but I don't have a good proof document. So here it is.

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Avoiding Reflection (And Such) In Go
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Dec 03, 2015
Programming, Golang

So, as previous posts show, I like Go well enough. But as a computer-language polyglot, "Go programmer" is not part of my identity, and I try for a balanced view. It is very human to go overboard in both praise and criticism, both easy to find online.

I open with this because this post will take a, ahh, let's say nuanced position on Go, in that it is going to agree a bit with both sides. Go's type system is weak and there are cases where you can only accomplish something via interface{}, reflection, copy/paste, or code generation... but in a rush to talk about what Go doesn't have, what it does have is too often neglected. When using a tool to solve problems what matters is whether there exists a good solution with that tool, not whether a direct port of a good solution from some other tool works. There certainly are real problems that lack good solutions in Go, but that set of problems is smaller than is sometimes supposed.

Some languages provide many power tools, and it is easy to use a bit of one and a bit of another without ever using any individual tool very deeply. Go provides you only a few tools, so you should use each fully.

If your Go code is a horrible copy/paste disaster, you must figure out whether it is because you are not using tools fully, or if you are missing tools. If you are missing tools, use another tool set. I do not consider that any sort of "concession", because I'm not too interested in whether you use Go; I'm interested in showing people how to fully use tools. All of these techniques will work in other languages as well, with varying degrees of convenience.

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It's 2015. Why do we still write insecure software?
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Jan 19, 2015
Programming, Golang

I've read a lot of programming blogs, and if you're reading this, you probably have too. So let me tell you up-front this is not your usual security rant that boils down to "just try harder!" Let's talk about smart, experienced programmers who are trying to write secure code, even if they are not security "experts" per se. This is an important set of people, because there is more security-related software in the world to write than can be written by security experts.

In a perfect world, setting that as the target audience would conclude this essay. As your browser's scrollbar shows in the full view, this essay continues on for quite a while. Alas, decades of experience and a trained reasonably high intelligence are not sufficient to write secure software in the current coding environment.

That's also the highest amount of qualifications that can be feasibly brought to bear at any reasonable scale, so in practice that's equivalent to saying it's impossible to write secure software in the current coding environment.

Let's talk about why it's so hard. My thesis is simple:

We write insecure software because our coding environment makes it easier to write insecure software than secure software.

But exploring what it fully means can lead some surprising places. Please join me on a journey as I try to show you why that is not trivially true, but in fact, profoundly true. We do not occasionally pick up insecure tools, like a broken encryption routine or misusing a web framework; we are fish swimming in an ocean of insecurity, oblivious to how steeped in it we are.

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Go: More UNIX than UNIX
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Apr 29, 2014
Programming, Golang

Go comes in part from Rob Pike and Ken Thompson, both influential in early UNIX. Both Rob Pike and Ken Thompson also were influential in working on Plan 9, a followup to UNIX.

UNIX's ideal is that "everything is a file". In Go terminology, this is a declaration that everything should be accessible via a uniform interface, which the OS specially privileges. One of Plan 9's core reasons for existing is that UNIX didn't take this anywhere near as far as it could be taken, and it goes much further in making everything accessible as a file in a directory structure.

I'm skeptical of both of these approaches. Everything isn't a "file".

There's numerous "files" that require ioctls to correctly manipulate, which are arbitrary extensions outside of the file interface. On the flip side, there are all kinds of "files" that can't be seeked, such as sockets, or files that can't be closed, like UDP streams. Pretty much every element of the file interface is one that doesn't apply to some "file", somewhere.

The Procrustean approach to software engineering tends to have the same results as Procrustes himself did, gravely or even fatally wounding the code in question.

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