Choosing between useState and useReducer in React

Right now I’m designing a rather important architecture at work, and I’m using React for it. After writing a simple enough implementation with Redux, I came to the conclusion that, in fact, I don’t need Redux in this architecture, since I’m only storing auth information. Context API seems to be enough.

So, in order to have a mutable and reactive value in the application context, I must choose between useState and useReducer hooks.

While studying the matter, I found a rather good answer to this question:

• When it’s just an independent element of state you’re managing: useState;
• When one element of your state relies on the value of another element of your state in order to update: useReducer.

Although the examples given by the author are way too long, the idea is spot on. In my particular case, since the state is just a monolithic block of data, useState seems to fit my needs.

False memory leak reports of static objects

I was having a weird memory leak report in a C++ program, happening right after I close it, and triggered by a call to _CrtDumpMemoryLeaks, which exists in the very end of WinMain function in WinLamb. I was puzzled, because I’ve commented everything out, and I still had the memory leak.

Turns out _CrtDumpMemoryLeaks is called at the end of WinMain, before the static object destructors are called. And there you go: if any statically allocated object had made a heap allocation, the memory won’t be freed yet, thus the report.

I’m not the only one with this problem, but so far no solution had any effect. By now I’ll just avoid static allocation of objects which alloc memory on the heap, and carry on with life. Maybe I’m too used to the JavaScript blessings.

What types are heap-allocated in Rust

Today I stumbled on this question regarding which standard Rust types do alloc in the heap. I have this question popping in my head quite often, so here are the heap-allocated ones:

• Box, simple heap allocation;
• Rc, reference counter;
• Arc, thread-safe atomic reference counter;
• collections.

Reference to the answer can be found here.

Firefox: can’t see menu separators in Linux

In Linux, I was having a problem when using Firefox. After some version update, the menu separator lines simply disappear. After searching around after a solution to this very annoying problem, I found another userChrome.css customization:

/* Make separators in menus easier to see */
menuseparator {
  -moz-appearance: none !important; /* nothing changes without this */
  background: #d4d2d1 !important;
  height: 1px !important;
  padding: 0 !important;
  margin: 3px 5px !important;
}

Make sure it’s loading is enabled. After restarting Firefox, the menu separators were back in all their glory.

Restore loading blue circle throbber in Firefox

Since Firefox 57 the loading icon has changed. Previously you’d see a blue circle spinning, now you see a dot moving horizontally. Personally, I prefer the old one.

So there’s this tip I found a while in the fantastic /r/FirefoxCSS Reddit, which restores the old throbber. Fortunately, Firefox developers kept the old animation file within the package, so we can still use them.

The following CSS must be added to “userChrome.css” file:

/* Revert tab throbber - for Nightly 57 as of 9/20/2017 */
.tab-throbber[busy]::before {
  background-image: url('chrome://global/skin/icons/loading.png') !important;
  animation: unset !important;
}
.tab-throbber[busy]:not([progress])::before {
  /* Grays the blue during "Connecting" state */
  filter: grayscale(100%);
}
@media (min-resolution: 2dppx) {
  .tab-throbber[busy]::before {
    background-image: url('chrome://global/skin/icons/loading@2x.png') !important;
  }
}

The “userChrome.css” is located in your Firefox profile folder. If it doesn’t exist, you can create it. Also, make sure it’s loading is enabled.

Override Chrome policy in Linux

If you happen to have Google Chrome settings managed by your network administration, on Linux, the fixed settings are stored into JSON files in the folder:

/etc/opt/chrome/policies/

If you have write permissions, you can change the settings you want. You don’t even need to restart Chrome to the changes start working. This has been tested in Chrome 77.

Let Go website generate your documentation

When trying to figure out how go doc command works, I just found out that I don’t need to use it.

There’s an incredible feature of Go documentation website: it can generate and display the documentation of all your project, straight from GitHub – and other websites too. The generated HTML is very polished.

To use it, append your GitHub user name and repo to their URL, such as:

https://godoc.org/github.com/username/reponame

Even more interesting: all types and Go built-in types are automatically linked. And it also provides direct links to GitHub source files. On top of all that, it’s very fast. Written in Go, I suppose.

Being a C language admirer, the more I work with Go, the more I like its simplicity.