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I'm sorry but I was smart and chose to ignore C++ as much as I could after C :)
Or rather, when to define an
initialize with a block as opposed to new
Oh, then for C it's like this:
void x_initialize(X *x) {
// set all the stuff in x, which was uninit memory
}
X *x_new() {
X *x = malloc(sizeof(X));
x_initialize(x);
return x;
}
Since crystal auto-defines new to do this for you, you should only define your own new if you need to change that malloc call to allocate your structure differently.
I'll think about this. Currently I do the following to initialize my ivars for my vec2, and also allow 0-1 arity construction:
def initialize(@x, @y); end
def self.new(value : T = 0.0)
new value, value
end
how about
def initialize(@x, @y); end
def initialize(value = 0.0)
initialize(value, value)
end
<riza> yeah, like @suskeyhose's example
Can you give an example within the current context of when you should define new, or does it not apply in any way you can think here?
As an absolute newbie with no knowledge of the allocation scheme and only reading what I have in the reference docs, I'd prefer only redefining self.new for changes to the allocation scheme, doing overrides for initialize, and if absolutely needed making a self.of method for alternate construction methods which use the same allocation scheme.
You mean like making object pools and then overriding new and finalize to just mess with the object pool?
Ok, I see. I will switch to overriding
initialize from now on unless I need to change the allocation strategy.
THat makes the most sense to me now that I understand it better.
I guess I defined new for extra constructors because it mapped better to my brain, probably because it is a class method.
The specialness of initialize confused me
What about the
new method that prompted this question early today? def self.new(&)
res = new
res.each_index { |i| res[i] = yield i }
res
end
Since my struct is
Indexable I do this to allow passing a block
Example usages:
def self.rand(min : T = 0.0, max : T = 1.0)
new { Random.rand min..max }
end
def self.rand(min : self = ZERO, max : self = ONES)
new { |i| Random.rand min[i]..max[i] }
end
Yeah, that makes sense to me if Crystal doesn't provide a way to pass a block via initialize normally
Anyone ever wish there was a way to mixin a module with instance and class methods and it doing the logical thing, rather than choosing how they are converted with
include vs extend?
I finally see the answer to my question. A break inside a block breaks from the method that called the block
Which makes me curious about this
def something
yield
end
def pass
something { yield }
puts "hey"
end
pass do
break
enddoes it print "hey"?
<riza> this is also true of
next
<riza> https://carc.in/#/r/bluv
That answered my question
I'm guessing I need a macro to make this generic using
Indexable instead of x/y/z/w in order to make a mixin that can be added to 2d, 3d and 4d vectors? The short-circuiting behavior of && tells me yes def <=>(other : self)
@x <=> other.x && @y <=> other.y
end
I'm just hoping macros are expanded after type merging
Make it generic as in, using
each or something from Indexable rather than the logic explicitly needing to know about the ivars
But I think we meant the same thing
<riza> or you can use a macro to build out the guts of the class
@mjfiano:matrix.org check how struct comparison is implemented: https://github.com/crystal-lang/crystal/blob/13dd77ef01c0d55f2d43372f97c648ff81c737d9/src/struct.cr#L66-L76