Someone new to Ruby will the WTF is the ! for?
Every Ruby tutorial explains that an exclamation mark means in-place, and this convention is consistent across Ruby libraries, unlike Python.
In the Python case, `list.sort()` operates on the object, so you can kind of expect it to do mutation (but there's no convention / guarantee). Though it only makes sense as a function that the list object itself implements.
`sorted` is a general function that gives you a sorted list from any iterable, and because working with iterables is such a common thing in software, Python has a bunch of standard functions like that. It's nice because you learn them once and they apply absolutely everywhere.
Ultimately you learn the behaviours of a language and they become second nature. I find both Ruby and Python very clean and easy to read.
the meaning is the same high level: it has side effects, being it a destructive update, an in place operation or throwing an exception.
> `sorted` is a general function that gives you a sorted list from any iterable
iterable in Python is a very loose concept though.
And it's not very consistent too
sorted("gheliabciou")
['a', 'b', 'c', 'e', 'g', 'h', 'i', 'i', 'l', 'o', 'u']
in Ruby it makes much more sense
"gheliabciou".chars.sort.join
"abceghiilou"
because a string cannot be sorted, sorting a string makes no sense, you sort the chars composing it.
Also, Python could not do this for many years, while Ruby could no prob
sorted("gheliabciouรโโจโ๐๐๐ถ๐๐ธ๐บ๐ท๐๐ใใ๐ด")Edit: ok, some do and some donโt. ๐ถ is allowed but :laugh_with_tears: isnโt. I guess thereโs a specific list of emojis that are getting stripped.
In that way `sorted` _is_ totally consistent - it always takes an iterable and returns a list of the elements. If we can't agree on that then I don't think there's much of a discussion to be had here.
except Iterable is the wrong "interface"
in Python it is defined as
> An iterable is any Python object capable of returning its members one at a time, permitting it to be iterated over in a for-loop.
which is not always what you want for sorting
quicksort doesn't work one element at a time
so basically you have to extract all the elements before sorting them
what about infinite streams?
At least Ruby Enumerable mixins explicitly states that
> The Enumerable mixin provides collection classes with several traversal and searching methods, and with the ability to __sort__.
Another problem with sorted is that it accepts any iterable, true, returning a list of items, but it is not clear how you can tell if the object is an iterbale or not
>>> sorted(123)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'int' object is not iterable
>>> isinstance(123, iterable)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'iterable' is not defined
maybe it's because int is not iterable?
>>> isinstace("abc", iterable)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'iterable' is not defined
# fails for strings in Python 2
>>> try:
_ = iter(some_object)
except TypeError as te:
print('is not iterable')
# if 2.6 >= Python < 3.3
from collections import Iterable
# if Python >= 3.3
from collections.abc import Iterable # <- personal note, abc stands for...? core maybe?
# no idea on how to do it in Python < 2.6
>>> isinstance("abc", Iterable)
True
Checking isinstance(obj, Iterable) detects classes that are registered as Iterable or that have an __iter__() method, but it does not detect classes that iterate with the __getitem__() method. The only reliable way to determine whether an object is iterable is to call iter(obj).
while in Ruby it's straightforward
[3] pry(main)> [1, 2].is_a? Enumerable
=> true
[4] pry(main)> "abc".is_a? Enumerable
=> false
[5] pry(main)> "abc".chars.is_a? Enumerable
=> trueHowever, the destructiveness semantic has been significantly overloaded over the time, so each Ruby (Rails) project probably interprets them in a different way, and it ends up having arbitrary semantics.
I'm used to it, but I personally think that for the reason above, it's not a good syntax/semantic to have in a language.
I wouldn't go so far to say it is arbitrary (unless someone uses it wrongly :) ).
As far as I know, a bang name only exists if a non-bang name exists as well. And the one with ! indicates an unexpected or comparatively dangerous outcome, such as a mutation, raising an exception, bypassing some normal check, etc.
This takes so little time to learn. Same with ?.
While ! is not always the same meaning, it exists when there is a non-bang version; and it means "watch out, this does some sh*t". Maybe it means mutating the source, or maybe it means "doesn't take the usual path", as with Active Record stuff (raising an exception if validations fail on save instead of just returning false).
And the ? is a godsend, as you can clearly indicate functions which return a boolean (or intentionally truthy) value. As naming functions is a chore, and one which can have significant impact on code readability later, the ! and ? have good value when used properly.
For example, Python's sorted() vs list.sort(). If you are new to Python, and you see sorted(list), you may wonder if that is telling you if the list is sorted or sorting the list. It's actually also very awkward, because most functions are named as their actions in present tense, not in past tense. The built-in Python function "sorted" really should be "sort".
In the list of Python built-in functions, you see present tense verbs like slice(), sum(), round(), etc. Those are inconsistent with sorted() and reversed(). When we see a past tense verb, it feels like a question. With Ruby, if it's a question, it ends with a ?.
BTW, why the hell is Python sorted() and reversed() not just called sort() and reverse()?
And while I'm ranting about inconsistencies, Python my_list.sort() mutates my_list, while sorted(my_list) doesn't. In Ruby, my_list.sort returns my_list sorted, without mutating. my_list.sort!. That is consistent and concise, and the bang warns you that it is destructive.
To me, the ! and ? syntax in Rugby is genius. It is a language wide self documenting tool to explain a dangerous function and a boolean, which make total sense.
One thing I think Ruby gets right is the naming convention for methods that modify the object they're called on (<obj>.<method>!) and callables in general that return a boolean (<callable>?).
My biggest gripe with Ruby is the class implementation. I find metaclasses a bit more difficult to understand in Ruby. I hate that I can't easy determine where a given method of an arbitrary object is defined.
I recall that it wasn't uncommon for popular libraries to "open up" a class that was an integral part of Rails and redefine methods, overriding the original implementation. I recall trying to figure out why the method I was calling wasn't returning the value I expected, even after reading the Rails source. Come to find out, some random library had overridden it. They'd matched the behavior of a previous Rails version, but the Rails behavior had since changed. I spent hours on that specific problem and still resent it to this day :P.
https://tenderlovemaking.com/2016/02/05/i-am-a-puts-debugger...
The relevant bit is under the heading:
> Iโm calling a method, but I donโt know where it goes
def index
p method(:render).source_location
render params[:id]
end
my_object.method(:my_method).source_location # returns path/to/file:[line number]