# Strange syntax sugar **URL:** \ **Category:** ruby-talk\ **Created:** [24 April 2007 00:40 UTC](https://rubytalk.org/t/strange-syntax-sugar/37142 "2007-04-24T00:40:06Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![aalfred](https://avatars.discourse-cdn.com/v4/letter/a/6a8cbe/32.png) [@aalfred](https://rubytalk.org/u/aalfred)\ **Post date:** [24 April 2007 00:40 UTC](https://rubytalk.org/t/strange-syntax-sugar/37142/1 "2007-04-24T00:40:06Z")
I've recently had to deal with lots of assignments, where most of them looked like those two lines:   foo = bar if !bar.nil? # (case 1) or   foo = bar if foo.nil? && !bar.nil? # (case 2) (I know it could be written using 'unless', but I strongly dislike 'unless') Then, while doing some refactoring of the code (and while searching for more idiomatic form to gain some more clarity in the code) I rewrote those as:   foo ??= bar # case 1   foo !!= bar # case 2 At the end it turned out there were only those two cases:   - case 1: 'do-not-assign-nil', and   - case 2: 'do-not-assign-nil' for '||=' (similarity with !!=) I thought I 'discovered' new fine operators! But I later found out that these cannot be new operators, but are just a possible syntatic sugar. If you cannot understand those two lines quick, they are probably useless. And I admit that after rethinking they were not so simple to understand anymore, and they do not map clearly into: "foo \= bar 'stands for' foo = foo \ bar". But the code still looked 'cute' (or at least more 'clean') to me! And so I decided to post it just as a question of what others think about it, about how often they would use it, and if anyone likes it at all. This is not a proposal to sweeten the (already sweet) ruby syntax! > **···** > > -- > Alfred ---
**Author:** ![Jeff](https://avatars.discourse-cdn.com/v4/letter/j/e19b73/32.png) [@Jeff](https://rubytalk.org/u/Jeff)\ **Post date:** [24 April 2007 03:37 UTC](https://rubytalk.org/t/strange-syntax-sugar/37142/2 "2007-04-24T03:37:17Z")
I think you won't need your new sugar if you just rewrite the originals: foo = bar if bar # case 1 foo ||= bar if bar # case 2 That's the simplest and cleanest, I think. Jeff softiesonrails.com > **···** > > On Apr 23, 7:40 pm, aalfred \ wrote: > > > I've recently had to deal with lots of assignments, where most of them > > looked > > like those two lines: > > > >   foo = bar if !bar.nil? # (case 1) or > >   foo = bar if foo.nil? && !bar.nil? # (case 2) > > > > (I know it could be written using 'unless', but I strongly dislike > > 'unless') ---
**Author:** ![Jan\_Svitok](https://avatars.discourse-cdn.com/v4/letter/j/cab0a1/32.png) [@Jan\_Svitok](https://rubytalk.org/u/Jan_Svitok)\ **Post date:** [24 April 2007 06:56 UTC](https://rubytalk.org/t/strange-syntax-sugar/37142/3 "2007-04-24T06:56:25Z")
Note thast when bar == false it won't work. Jano > **···** > > On 4/24/07, Jeff \ wrote: > > > On Apr 23, 7:40 pm, aalfred \ wrote: > > \> I've recently had to deal with lots of assignments, where most of them > > \> looked > > \> like those two lines: > > \> > > \> foo = bar if !bar.nil? # (case 1) or > > \> foo = bar if foo.nil? && !bar.nil? # (case 2) > > \> > > \> (I know it could be written using 'unless', but I strongly dislike > > \> 'unless') > > \> > > > > I think you won't need your new sugar if you just rewrite the > > originals: > > > > foo = bar if bar # case 1 > > foo ||= bar if bar # case 2 > > > > That's the simplest and cleanest, I think. > > > > Jeff > > softiesonrails.com ---
**Author:** ![Robert\_K1](https://yyz1.discourse-cdn.com/flex029/user_avatar/rubytalk.org/robert_k1/32/1830_2.png) [@Robert\_K1](https://rubytalk.org/u/Robert_K1)\ **Post date:** [24 April 2007 07:35 UTC](https://rubytalk.org/t/strange-syntax-sugar/37142/4 "2007-04-24T07:35:06Z")
That's doubling the effort in the second case. Rather do foo &&= bar foo ||= bar As Jano pointed out, this reacts to false in the same way as to nil which might or might not be what you want. Kind regards   robert > **···** > > On 24.04.2007 05:37, Jeff wrote: > > > On Apr 23, 7:40 pm, aalfred \ wrote: > > > > > I've recently had to deal with lots of assignments, where most of them > > > looked > > > like those two lines: > > > > > >   foo = bar if !bar.nil? # (case 1) or > > >   foo = bar if foo.nil? && !bar.nil? # (case 2) > > > > > > (I know it could be written using 'unless', but I strongly dislike > > > 'unless') > > > > I think you won't need your new sugar if you just rewrite the > > originals: > > > > foo = bar if bar # case 1 > > foo ||= bar if bar # case 2 > > > > That's the simplest and cleanest, I think. ---
**Author:** ![aalfred](https://avatars.discourse-cdn.com/v4/letter/a/6a8cbe/32.png) [@aalfred](https://rubytalk.org/u/aalfred)\ **Post date:** [24 April 2007 10:40 UTC](https://rubytalk.org/t/strange-syntax-sugar/37142/5 "2007-04-24T10:40:06Z")
There is a subtelty in the assignment that is hard to see at the first glance: you \*never\* assign nil to foo (but assign can false). So your rewrite is not equivalent. > **···** > > On Apr 24, 5:37 am, Jeff \ wrote: > > > On Apr 23, 7:40 pm, aalfred \ wrote: > > > > \> I've recently had to deal with lots of assignments, where most of them > > \> looked > > \> like those two lines: > > > > \> foo = bar if !bar.nil? # (case 1) or > > \> foo = bar if foo.nil? && !bar.nil? # (case 2) > > > > \> (I know it could be written using 'unless', but I strongly dislike > > \> 'unless') > > > > I think you won't need your new sugar if you just rewrite the > > originals: > > > > foo = bar if bar # case 1 > > foo ||= bar if bar # case 2 > > > > That's the simplest and cleanest, I think. ---
**Author:** ![Nobuyoshi\_Nakada1](https://avatars.discourse-cdn.com/v4/letter/n/9f8e36/32.png) [@Nobuyoshi\_Nakada1](https://rubytalk.org/u/Nobuyoshi_Nakada1)\ **Post date:** [26 April 2007 15:24 UTC](https://rubytalk.org/t/strange-syntax-sugar/37142/6 "2007-04-26T15:24:14Z")
Hi, At Tue, 24 Apr 2007 19:40:06 +0900, aalfred wrote in [ruby-talk:248941]: > \> foo = bar if bar # case 1 > \> foo ||= bar if bar # case 2 > \> > \> That's the simplest and cleanest, I think. > > There is a subtelty in the assignment that is hard to see at the first > glance: you \*never\* assign nil to foo (but assign can false). > So your rewrite is not equivalent. Ruby doesn't distinguish nil and false as boolean, so if ??= were introduced it would not assign false. > **···** > > -- > Nobu Nakada