leafo
commented
12 years ago It's not apparent at first, but using a dedicated character for building hash tables, : let's you do some interesting things with syntax:
I can write open hash tables, tables that aren't bounded by { and }:
x = hello: world
y = some: "value", another: 2323
my_func 1, 2, 3, opt1: "value", opt2: "value2"This already makes the syntax look a lot cleaner when writing small tables. In the last example we've essentially written named arguments thanks to the syntax (Think of Ruby). Imagine if I were using =, the first example would be x = hello = world. That syntax is too ambiguous with assignment to derive a table out of it.
I can also use the dedicated : operator in other places now too. Here I used it as a prefix operator to quickly assign both the key and the value:
hello, world = 100, "xxx"
z = :hello, :world
-- This is shorthand for:
--
-- z = { hello: hello, world: world }And because I am using : for building tables, I couldn't use it for calling methods on tables like in Lua because of similar syntactic ambiguity issues like mentioned above.
I experimented in with a few options, both 1 and 2 character ones, but I decided that for such a common operator it should be 1 character. I settled on \. I admit it felt strange at first, but after using it for a while now, it's feels as just natural as any other character.
Having a unique character for the method invocation also lets us do some interesting things with the syntax.
For example, when you use the backslash but don't pass in any arguments, it creates a new function that is bound to the receiving object which calls the named method. I call these function stubs.
Here's an example:
-- a simple object with 1 method
counter_obj =
count: 0
increment: =>
@count += 1
print "The count is", @count
counter_obj\increment! -- prints "The count is 1"
-- notice here how we use \ but don't pass any arguments
bound_method = counter_obj\increment
bound_method! -- "The count is 2"
print counter_obj.count -- prints 2I also enable the use of \ as a prefix operator for the import statement. It does the same thing as above, creates a bound function for the table that is being imported from.
There's even one more MoonScript construct that's only possible if I use unique operators, check out how the with statement works.
So that's why I use backslash. Write some MoonScript and you'll find that it fits perfectly.
nightsailer
zah
mattaylor
pwhelan
stevedonovan
nilnor
etandel
ludamad
adderlan
tbastos
devast8a
hems
codic12
I know MoonScript replace ':' with '\' to call an instance method, but I think it's sooooooo weird. As most language, '\' meant escape. So, try to read: file\read vs file.read vs file:read
When reading code, I think the first way is hardest.
and try these code:
obj1\method2 "\01\002\010\"
And, I don't think so use ':' to assigning a value to key in a table is better than '='.
So, why not keep ':' and '=' behavior?
It's bad idea to change the operator behavior, it make hard to port code between Lua and Moonscript, also make people more confused.