talking about factories factories are
simply functions that create objects and
return them in most cases you can use
factories instead of classes and
factories are much simpler and less
convoluted than classes are this is a
weekly show where we try to become more
confident and excited about programming
by learning intriguing things that we
didn’t know before
pre-requisite in order to understand
this video you need to be familiar with
closures if you’re not completely sure
what closures are you should watch the
previous episode on that topic first
before I show you a factory function I
want to show you a class this is a dog
class it does some setup in the
constructor assigns a property to itself
called sound the class also has a method
talk which uses that sound
we then instantiate at all say foods
which we then call talk on and sniffles
promptly tells us what this is fine but
there are a couple of annoying things
with classes if we assign the top method
to something like click handler here
things will break because now the this
keyword inside the top method here will
not be sniffles this is going to refer
to something else in this case I think
it’s going to be the Dom element or
something that it’s not important
exactly what but what is important is
that it isn’t going to refer to sniffles
like you would intuitively expect to
work around this you can use bind to
force this to be sniffles this is a very
common thing to do but it hurts my
gentle and beautiful soul to look at
this code it looks like cold blue
another way of dealing with this problem
is to wrap the top call in a function
like this that looks better
but it annoys me that I have to remember
to do this at all to me it feels like a
stupid trap in a shitty computer game in
fact I think that the concept of this
and new in JavaScript feels like that in
general
new and this are some kind of
unintuitive weird clown rainbow trap
that you just trip over all the time and
I am so ashamed of it every time I
introduce people to JavaScript but there
is hope because in JavaScript you don’t
have to do classes in Java or C sharp
and some other languages you have to use
classes that’s the way of instantiating
objects but in JavaScript you have a bit
more freedom so maybe we can try some
other way enter factory functions here
is our dog re-written as a factory
function now dog is simply a function in
it we create a variable sum and we
assign the value woof to it we then
return a simple object literal with one
property Tork a function which logs out
the value of sum and because of the
awesomeness of closures top has access
to the variable sound a bonus feature
here is that the code outside of the Dom
doesn’t have access to the sound
variable so the sound variable is
actually properly private to the dog
which it isn’t in the class I notice
here that we are not using that this
keyword at all and because of that the
reference to the sound variable will
always be correct even when we use class
in the way that broke in the class
example like this I think that for
almost all cases you will be better off
using factories for other than classes
because your code will be simpler and
easier to reason about there is one case
where I think it’s not like to use
classes and that is if you find yourself
in a situation where you need to create
a lot of objects it
cause classes have a bit better
performance but note here when I say a
lot I mean a lot instantiating an object
on my computer using a factory takes
zero point zero point zero point zero
point four milliseconds using a class is
twice as fast actually 0.0.0.0 hmm point
two milliseconds if you do the math this
means that if you’re creating say 10,000
instances using classes over factories
will earn you a directed a to
milliseconds so if you’re creating just
a couple of hundred or even a couple of
thousand items per frame the performance
difference between a factory and class
is not going to matter to you if you are
creating more than 10,000 instances per
frame then classes might be for you but
you should really ask yourself if the
problem isn’t that you’re creating
10,000 items per frame in the first
place
in summary factories or simply functions
that create and return objects we looked
at a simple example of how you can use a
factory instead of a class and how the
factory is less convoluted than a class
we also talked about how classes are a
bit faster but that it is by so little
that it only matters if you’re creating
at ten thousand items per frame or more
do you have thoughts or questions maybe
you even disagree good post a youtube
comment down below and me or a fellow
viewers I’ll respond to your inquiry
again in this show we try to become more
excited and confidence about programming
I’m learning intriguing things that we
didn’t know before new episodes every
Monday morning so make sure that you
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stay curious you