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I really like ruby's method naming convention for this: * `sort(arr)` returns a sorted copy of the input * `sort!(arr)` returns the sorted original methods th

I really like ruby's method naming convention for this: * `sort(arr)` returns a sorted copy of the input * `sort!(arr)` returns the sorted original methods that return booleans end in `?`, like `arr.sorted?` It's just a convention, but it's a nice way to let the writer know what will happen.

dmurray 5y ago
I'll just point out that this is originally from Scheme (I think... Maybe Scheme got it from a previous Lisp) but borrowed by Ruby. Neither Scheme nor Ruby do a perfect job with sticking to the naming convention, at least if we include popular libraries, but it is very handy and intuitive. https://stackoverflow.com/a/612588 https://stackoverflow.com/a/612588
canjobear 5y ago
The ! convention is ok but I don't think it's optimal because, in the presence of higher-order functions and related concepts, it's often not clear if a function should be marked as !. For example if I have a map function that applies a function f to a sequence, should I call it map! because I might pass in a function f that mutates the input? If so then it seems like any function that takes a function as input, or any function that might call a method on an object, should get marked with ! just in case. But if I don't mark it that way then the ! marking is not as informative: I might end up with a line consisting only of non-! functions which still mutates the input.
- zarzavat 5y ago
  map! would mean a function that performs a map in-place on the array by replacing the values. So it would depend on if the callback was encouraged to mutate the array or discouraged from doing so.
  - djur 5y ago
    Array#map! actually exists in Ruby, too. It mutates the array item by item. Enumerable#each doesn't have a bang, because it doesn't change the enumerable itself, even though it can mutate the objects contained in the enumerable. This is overall consistent -- there's a distinction between mutating the receiving object and mutating objects contained in or referred to by the receiving object.
- dragonwriter 5y ago
  Note that “!” in Ruby doesn’t conventionally mean “modifies the receiver”, it means “does something that is similar but less likely to be safe than a method with the same name without ‘!’”. A very common case of this is mutating versions of non-mutating methods, but (1) mutating methods (in stdlib or other idiomatic code bases) that have no non-mutating equivalent are not named with a “!”, and (2) methods are sometimes named with “!” because they do dangerous things compared to a base method that are not mutating the receiver.
pansa2 5y ago
> `sort(arr)` returns a sorted copy of the input > `sort!(arr)` returns the sorted original Python has a naming convention as well: `sorted(arr)` returns a sorted copy and `arr.sort()` works in-place (and returns None). However, I've always thought it's a bit odd that one is a function and the other is a method.

dmurray 5y ago

I'll just point out that this is originally from Scheme (I think... Maybe Scheme got it from a previous Lisp) but borrowed by Ruby. Neither Scheme nor Ruby do a perfect job with sticking to the naming convention, at least if we include popular libraries, but it is very handy and intuitive. https://stackoverflow.com/a/612588 https://stackoverflow.com/a/612588

canjobear 5y ago

The ! convention is ok but I don't think it's optimal because, in the presence of higher-order functions and related concepts, it's often not clear if a function should be marked as !. For example if I have a map function that applies a function f to a sequence, should I call it map! because I might pass in a function f that mutates the input? If so then it seems like any function that takes a function as input, or any function that might call a method on an object, should get marked with ! just in case. But if I don't mark it that way then the ! marking is not as informative: I might end up with a line consisting only of non-! functions which still mutates the input.

zarzavat 5y ago
map! would mean a function that performs a map in-place on the array by replacing the values. So it would depend on if the callback was encouraged to mutate the array or discouraged from doing so.
- djur 5y ago
  Array#map! actually exists in Ruby, too. It mutates the array item by item. Enumerable#each doesn't have a bang, because it doesn't change the enumerable itself, even though it can mutate the objects contained in the enumerable. This is overall consistent -- there's a distinction between mutating the receiving object and mutating objects contained in or referred to by the receiving object.
dragonwriter 5y ago
Note that “!” in Ruby doesn’t conventionally mean “modifies the receiver”, it means “does something that is similar but less likely to be safe than a method with the same name without ‘!’”. A very common case of this is mutating versions of non-mutating methods, but (1) mutating methods (in stdlib or other idiomatic code bases) that have no non-mutating equivalent are not named with a “!”, and (2) methods are sometimes named with “!” because they do dangerous things compared to a base method that are not mutating the receiver.

pansa2 5y ago

> `sort(arr)` returns a sorted copy of the input > `sort!(arr)` returns the sorted original Python has a naming convention as well: `sorted(arr)` returns a sorted copy and `arr.sort()` works in-place (and returns None). However, I've always thought it's a bit odd that one is a function and the other is a method.