DavidJCobb

mGBA features a very basic embedded debugger. It has a help command, but this command doesn't explain what arguments any of the commands accept (or require). One has to look at mGBA's source code to get that information.

Syntax

Values

Integers are decimal by default, but can be prefixed with 0x or $ to allow hexadecimal. The 0b prefix marks binary literals. Any command which takes a memory address expects to receive it in the form of an integer.

Literals of the form $01:23 have a segment of 01 and a non-segment value of 0x00000023.

What are assertions?

Assertions are a means to verify that program invariants have not been violated. Put simply: you assert that impossible things are not happening, and if that assertion ever fails — if the impossible is happening — then your program should halt execution immediately, generally for two reasons:

If your program has done something that should (if your program is properly written) be logically impossible, then you will likely only detect the problem after the fact. You don't know what went wrong, you don't know how it went wrong, and you don't know the scope of the damage, and this means both that your program can't reliably correct the error and that your program can no longer trust itself at all. The least dangerous thing to do is stop executing immediately — crash, on purpose, before your program can do anything else that shouldn't be possible.
Depending on your choice of programming language and environment, halting execution may give you an opportunity t

Ascii85, also known as base85, is an encoding similar in concept to base64. Where base64 uses four ASCII characters to represent three source bytes (thereby inflating the data size by 33%), ascii85 uses five ASCII characters to represent four source bytes (thereby inflating the data size by 25%).

This script can be used to encode and decode a DataView as ascii85. Spawn an Ascii85Codec with the desired configuration, and then call its member functions as appropriate. In particular, this class should be appropriate for storing a DataView inside of Local Storage with the smallest possible size (if you use the STORAGE_CHARSET offered).

Note that we do not perform any error-checking during the decode step. Ascii85Codec offers a validate member function that can be run on an encoded string to verify that it contains no illegal characters; this can be run prior to decoding in any situation where the input data is untrusted.

Implementation notes

The `S

Userscript to fix issues on Raymond Chen's blog, and improve the browsing experience:

Redirect old-format links within the blog as close to their present-day destinations as possible
Add pagination to the top, and allow pagination between months (helps when reading in chronological order, month by month, on mobile)

Might expand this into a full WebExtension later? There are some articles that used to have inline JavaScript which now just renders as plain-text; recreating these scripts within a WebExtension (no eval!!) could be useful.

JavaScript event bubbling example

When JavaScript fires an event, like click, it doesn't just fire it on the event target (i.e. the thing that was clicked). It also fires the event on every ancestor element. This means that an event listener on an ancestor can handle clicks on any of its children.

The code below demonstrates this with a list, where we want to react to the user clicking any list item, and we want our reaction to take into account which list item they clicked. We use a listener on the entire list, and just check e.target to see what list item was clicked.

The as_const function returns a Proxy wrapping the passed-in argument. This proxy attempts to prevent all modifications to the underlying object. The difference between this and using Object.freeze is that the latter makes the object itself immutable, while as_const simply prevents direct changes to the object via a specific reference to the object. Additionally, as_const prevents changes to any object that is referenced through the proxy (i.e. as_const(foo).bar.data = 5 is equivalent to as_const(foo.bar).data = 5 and will throw an exception).

In C++ terms, Object.freeze is akin to instantiating a const Object, whereas the result of as_const is a const Object& and the original object can still be modified elsewhere.

This idea is leaky enough that I would recommend against using it. If you need functionality like this, prefer a language that offers it reliably as a built-in feature.

	// ==UserScript==
	// @name GitHub mobile fix for symbols dialog
	// @version 1
	// @grant none
	// @run-at document-start
	// @inject-into page
	// @match https://.github.com/
	// ==/UserScript==

	let fix_installed = false;

	//
	// This file contains a JavaScript tag function to let you
	// define regexes without needing to backslash-escape every
	// forward slash in the regex text; good for URLs.
	//

	function regex(tag) {
	return new RegExp(tag.raw, "i");
	}

	// given:
	QPlainTextEdit* widget;
	int maxlength;

	auto* doc = widget->document();
	assert(doc);
	QObject::connect(doc, &QTextDocument::contentsChange, this, [maxlength, widget](int pos, int removed, int added) {
	if (added - removed <= 0)
	return;
	if (maxlength < 0)

	--
	-- This two-file add-on will track your position every tenth of a second
	-- (or thirtieth when mounted, if I got the update re-registration right)
	-- and maintain a grid of where you've been. Every fifth of a second, it
	-- redraws the grid using Texture controls rendered in 3D as gridlines.
	--
	-- ISSUES:
	--
	-- - Performance (see below comments)
	--