If any of the objects dies, then the corresponding value is no longer kept alive simply by being in that WeakMap. Say you have your invisibleProperty WeakMap filled up with a bunch of entries mapping various objects to their properties. Let me expand on that last point a little. It’s like adding an invisible property to an object that you can only look at if you look it up in some invisibleProperty WeakMap. Or maybe you want to track whether an Error object has been logged, or associate a DOM object with some information about it. You could map an object to some expensive-to-compute cached information, for example. In terms of usage, WeakMaps are good for annotating an object with data that isn’t useful if the object is no longer needed. Then it will keep the corresponding value alive. If a WeakMap is alive on the other hand, then it won’t keep any key or value alive unless something else is keeping a particular key alive. And anything they might contain, recursively. If a regular Map is alive, then so are all of its keys. The differences are (1) you can only use objects (and soon symbols) as WeakMap keys, (2) the API is limited to prevent retrieving any entries without having the corresponding key in hand, and (3) WeakMaps are hooked into the garbage collector (GC) so that they don’t keep as much stuff alive. WeakMaps are very similar to plain Maps where if you have a Map and a key, you can look up a value. Ephemerons-Effin’ Ron What?Įphemeron tables are the underlying data structure for JavaScript WeakMaps. It was also described in terms of the Squeak language and included post-mortem finalization, which is unavailable in JavaScript (and frankly sounds terrifying from an implementation point of view!) I thought I’d try my hand at writing up a shorter and hopefully simpler explanation covering only what is available in JS. I read Ephemerons explained today after finding it on Hacker News, and it was good but lengthy. Now, it's just me alone in my apartment with my guitar and piano. I played with the Ugly Ducklings until I moved to Lyon a couple years back. He is a multiple personality disorder musician with a history spanning classical, rock, funk, country and gospel. STEVEN FINK - bass guitar - Loving the low frequencies and life in the "back row", Steven finds his home helping Matthieu (our drummer) build the foundation on which the other Ducks can shine. The guys were kind enough to write up a bio for me, that I think fits me to a "T" : In France, I met an American singer who played with a French band The Ugly Ducklings. Mixing music and technology was very rewarding and a lot of fun. During the years that I played with these amazing people, I built and furnished a recording studio so that I could record and produce music. I was clearly the weakest link in the group - they were all fantastic musicians, and I was just loving the variety of styles that we would play from week to week. Oh the joy of playing music with other people.
A couple weeks later I found myself back playing music in a group. Since Brad was the bass player in our church's worship band at Southside Fellowship, there was now a vacancy, so I pitched the idea to play bass in the church's band. Until he suddenly moved to another city to be a worship leader at another church. He really helped me break through my blockage and I was really enjoying our lessons. Several months later, I'd already plateau'd so I went to a fabulous guitar player in our church named Brad Bailey to take some lessons (go to his website, have a listen, and prepare to be amazed because he's playing the bass and guitar at the same time). Twelve years later, a friend of mine decided he wanted to play guitar, so I figured I'd learn it too. And, as is too often the case, life happens - I got busy and stopped playing music. I really loved playing music in a group of people. I continued to play the tuba as my primary instrument throughout high school and my first year of college (picking up trumpet, trombone, baritone, and some drums along the way). I played that for a couple of concerts, then he moved me to tuba.
The orchestra director moved me to French horn because he needed a French horn. I went to orchestra and got to play drums for exactly 2 weeks. In middle school I wanted to play the drums. That was pretty much the end of my piano career. I replied "I did - I played it just like did", to which she replied, "yes but when I played the song, I played in a different key than what was written. At the start of one of my lessons, I played my assignment and the teacher asked me to play what was written on the music. My teacher gave me a new songs to learn at home and before leaving showed me what they should sound like. My life as a musician started out with piano lessons.
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