The Crystal programming language | http://crystal-lang.org | Fund Crystal's development: http://is.gd/X7PRtI | Docs: http://crystal-lang.org/docs/ | API: http://crystal-lang.org/api/
No idea how it maps to Crystal yet. Here is how I did the same in Nim with a static array as storage (and was able to re-use a lot of code because of it): https://git.mfiano.net/mfiano/origin.nim/src/branch/master/src/origin/vec.nim#L7
fixed
It makes some things easy, like extracting a column from a matrix to a vector: https://git.mfiano.net/mfiano/origin.nim/src/branch/master/src/origin/mat.nim#L589-L595
idk, nvm, deff not familiar with this stuff
The matrices I need are the same sizes squared: 4, 9, 16
which means rows x cols
But, np. I'm almost ready to take a break for today
mfiano: class instances are always on the heap (scattered, so worse for cache) and, importantly, need to be garbage collected.
Yes, I'm aware of that. I'm almost thinking that is an acceptable trade-off to make in favor of a nice chained mutable method API
But I'm not certain yet. If I can find a nicer balance with structs, that'd be better.
I'd like to write data to sqlite & read it back again from query results, all without writing custom serialization code. I like how JSON::Serializable works and would like something similar. Any suggestions?
Hold on though, it looks like
DB::Serializable only handles creating objects from query results & not creating table schema or formatting query strings to insert data?
Or else I'm missing some big piece of this? This looks like
JSON::Serializable except if it for some reason only gave you from_json but not to_json?
Not really, as there isn't a single way to do what you want. I.e. insert versus update
Plus the table should already be created, that would be out of scope
If it also handled migrations and such
Perhaps a dumb question, but is there any best practice as to when to use
x, @x, or self.x to refer to an instance variable in an instance method? I seem to be able to use all 3 with the same effect.
My guess is that
@x is the only "safe" thing that will always resolve to an ivar, even if there is another local var or method named x...so is there no reason to use the other 2, other than to make things less explicit and confusing? :)
"self.x" is a method (you are probably using the macro "getter") that returns "@x"
and "@x" is the actual instance var
so the best practice if you want to access to the instance var is to use the instance var "@x" :)
<hightower2> sometimes I wish that instead of making local vars be unprefixed, the lang designers chose to prefix local vars... so then the scope/lookup of all unprefixed vars like 'x' or 'var1' would be very uniform regardless of whether it was a property or method
<hightower2> well, I guess if one really wanted to do so, one could stick to a rule of always prefixing local vars with something, manually...
this way its always clear what is a method call and what isnt
however, a good usecase for using
self.x is if you have customer logic in the getter and/or are using a lazily initialized ivar
Oh, glossed over. lazy was already mentioned
Does crystal have anything like...I'm not sure what it's called, but in Nim, you can assign a slice to a slice of a variable...like:
var x = [1, 2, 3, 4, 5]
var y = [6, 7, 8, 9, 10]
x[1..2] = y[1..2] # x => [1, 7, 8, 4, 5]