Each of my Emacs packages has a Makefile to byte-compile all source files, run the tests, build a package file, and, in some cases, run the package in an interactive, temporary, isolated Emacs instance. These portable Makefiles have a similar structure and follow the same conventions. It would require more thought and feedback before I’d try to make it a standard, but these are conventions I’d like to see in other package Makefiles.

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Regardless of your opinions of the Go programming language, the primary implementation of Go, gc, is an incredible piece of software engineering. Everyone ought to be blown away by it! Yet not only is it undervalued in general, even the Go community itself doesn’t fully appreciate it. It’s not perfect, but it has unique features never before seen in a toolchain.

I saw (part of) a video, OS hacking: Purgeable memory, by Andreas Kling who’s writing an operating system called Serenity and recording videos his progress. In the video he implements purgeable memory as found on some Apple platforms by adding special support in the kernel. A process tells the kernel that a particular range of memory isn’t important, and so the kernel can reclaim if it the system is under memory pressure — the memory is purgeable.

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Despite the goal of JSON being a subset of JavaScript — which it failed to achieve (update: this was fixed) — parsing JSON is quite unlike parsing a programming language. For invalid inputs, the specific cause of error is often counter-intuitive. Normally this doesn’t matter, but I recently ran into a case where it does.

Suppose you don’t like the names car and cdr, the traditional identifiers for two halves of a lisp cons cell. This is misguided. A cons is really just a 2-tuple, and the halves don’t have any particular meaning on their own, even as “head” and “tail.” However, maybe this is really important to you so you want to do it anyway. What’s the best way to go about it?

There’s an old saying, let the knife do the work. Whether preparing food in the kitchen or whittling a piece of wood, don’t push your weight into the knife. Not only is it tiring, you’re much more likely to hurt yourself. Use the tool properly and little force will be required.

I regularly make throwaway “projects” and do a surprising amount of programming in /tmp. For Emacs Lisp, the equivalent is the *scratch* buffer. These are places where I can make a mess, and the mess usually gets cleaned up before it becomes a problem. A lot of my established projects (ex.) start out in volatile storage and only graduate to more permanent storage once the concept has proven itself.

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In software development there are many concepts that at first glance seem useful and sound, but, after considering the consequences of their implementation and use, are actually horrifying. Examples include thread cancellation, variable length arrays, and memory aliasing. GCC’s closure extension to C is another, and this little feature compromises the entire GNU toolchain.

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Yesterday I wrote about a legitimate use for variable length arrays. While recently discussing this topic with a co-worker, I also thought of a semi-legitimate use for alloca(), a non-standard “function” for dynamically allocating memory on the stack.

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The C99 (ISO/IEC 9899:1999) standard of C introduced a new, powerful feature called Variable Length Arrays (VLAs). The size of an array with automatic storage duration (i.e. stack allocated) can be determined at run time. Each instance of the array may even have a different length. Unlike alloca(), they’re a sanctioned form of dynamic stack allocation.