# Strange whitespace parsing behavior on Ruby 1.8.7 (patchlevel 249/302) **URL:** \ **Category:** ruby-talk\ **Created:** [2 November 2010 04:49 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692 "2010-11-02T04:49:52Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Ehsanul\_Hoque](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@Ehsanul\_Hoque](https://rubytalk.org/u/Ehsanul_Hoque)\ **Post date:** [2 November 2010 04:49 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/1 "2010-11-02T04:49:52Z")
An issue pops up when I use a method's integer return value in a function argument while performing arithmetic on that value. Then missing whitespace between the arithmetical operator and the second argument can cause random errors, but only if there is whitespace preceding the operator. I don't want to rush to judgement and call this a bug, but it certainly seems like one, hidden till now because you have have formatting that's slightly ugly for the error to turn up. Here's an irb session that demonstrates the issue: irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> x.slice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0) from (irb):71:in `size' from (irb):71 from :0irb(main):072:0\> ok(4,x.size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):72 from :0irb(main):074:0\> ok(4,x.size + 3)=\> nil ---
**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:** [2 November 2010 07:17 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/2 "2010-11-02T07:17:55Z")
Can you repost with proper indentation and line wrapping? Guessing from your text I assume you might have fallen into a unary / binary operator ambiguity. Kind regards robert > **···** > > On Tue, Nov 2, 2010 at 5:49 AM, Ehsanul Hoque \ wrote: > > > An issue pops up when I use a method's integer return value in a function argument while performing arithmetic on that value. Then missing whitespace between the arithmetical operator and the second argument can cause random errors, but only if there is whitespace preceding the operator. I don't want to rush to judgement and call this a bug, but it certainly seems like one, hidden till now because you have have formatting that's slightly ugly for the error to turn up. Here's an irb session that demonstrates the issue: > > irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> x.slice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0) from (irb):71:in `size' from (irb):71 from :0irb(main):072:0\> ok(4,x.size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):72 from :0irb(main):074:0\> ok(4,x.size + 3)=\> nil > > -- > remember.guy do |as, often| as.you\_can - without end > [http://blog.rubybestpractices.com/](http://blog.rubybestpractices.com/) ---
**Author:** ![Colin\_Bartlett1](https://avatars.discourse-cdn.com/v4/letter/c/dbc845/32.png) [@Colin\_Bartlett1](https://rubytalk.org/u/Colin_Bartlett1)\ **Post date:** [2 November 2010 11:19 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/3 "2010-11-02T11:19:33Z")
That seems to be a correct diagnosis. See below for the OP's irb session with formatting. For the OP: 7.abs + 3 #=\> 10 7.abs+3 #=\> 10 7.abs +3 #=\> ArgumentError: wrong number of arguments(1 for 0) ## Ruby parses the "+" in " +3" as a unary + on 3 giving integer 3, ## which means that integer 3 is an argument to abs, hence the error message. def okp( a, b ); a + b; end #=\> nil okp(4, 7.abs + 3) #=\> 14 okp(4, 7.abs+3) #=\> 14 okp(4, 7.abs +3) #=\> SyntaxError: (irb):23: syntax error,                           # unexpected tInteger, expecting ")" ## I leave that - and the next - one to Robert to explain! x = '123456' #=\> "123456" x.slice(1, x.size -2) #=\> SyntaxError: compile error(irb):63:                              # syntax error, unexpected ')',                              # expecting kDO\_BLOCK                              # from (irb):63 from :0 ## Again, the "-" in " -2" is parsed on a unary on 2 giving integer value -2. ## Why the ')' is unexpected I leave to Robert! \*\*\* the OP's irb session irb(main):062:0\* x = '123456'=\> "123456" irb(main):063:0\> x.slice(1, x.size -2) SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0 irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345" irb(main):065:0\> x.slice(1, x.size-2)=\> "2345" irb(main):066:0\> x.slice(1, x.size -2) SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0 irb(main):067:0\> x[x.size -3,1] ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0 irb(main):068:0\> x[x.size - 3,1]=\> "4" irb(main):069:0\> def ok(a,b) irb(main):070:1\> end=\> nil irb(main):071:0\> ok(x.size +3,4) ArgumentError: wrong number of arguments (2 for 0) from (irb):71:in `size' from (irb):71 from :0 irb(main):072:0\> ok(4,x.size +3) SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):72 from :0 irb(main):074:0\> ok(4,x.size + 3)=\> nil > **···** > > On Tue, Nov 2, 2010 at 7:17 AM, Robert Klemme \wrote: > > > Can you repost with proper indentation and line wrapping? > > Guessing from your text I assume you might have fallen > > into a unary / binary operator ambiguity. ---
**Author:** ![Ehsanul\_Hoque](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@Ehsanul\_Hoque](https://rubytalk.org/u/Ehsanul_Hoque)\ **Post date:** [2 November 2010 16:15 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/4 "2010-11-02T16:15:26Z")
> \> An issue pops up when I use a method's integer return value in a function argument while performing arithmetic on that value. Then missing whitespace between the arithmetical operator and the second argument can cause random errors, but only if there is whitespace preceding the operator. I don't want to rush to judgement and call this a bug, but it certainly seems like one, hidden till now because you have have formatting that's slightly ugly for the error to turn up. Here's an irb session that demonstrates the issue: > \> irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> x.slice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0) from (irb):71:in `size' from (irb):71 from :0irb(main):072:0\> ok(4,x.size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):72 from :0irb(main):074:0\> ok(4,x.size + 3)=\> nil > \> > > Can you repost with proper indentation and line wrapping? Guessing > from your text I assume you might have fallen into a unary / binary > operator ambiguity. > > Kind regards > > robert > > -- > remember.guy do |as, often| as.you\_can - without end > [http://blog.rubybestpractices.com/](http://blog.rubybestpractices.com/) Sorry about that, Hotmail's "rich text" formatting messed it up I believe. Here it goes again with plain text: irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0 irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> x.slice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0 irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0 irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0) from (irb):71:in `size' from (irb):71 from :0 irb(main):072:0\> ok(4,x.size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):72 from :0 irb(main):074:0\> ok(4,x.size + 3)=\> nil Insert mode ---
**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:** [2 November 2010 14:04 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/5 "2010-11-02T14:04:38Z")
Very generous. 🙂 Concluding from systematic experimentation I believe both errors you left for me are related to the fact how Ruby parses (or rather: tries to parse) in absence of brackets: 14:53:27 $ ruby19 -ce 'a(b.c +1)' Syntax OK 14:53:45 $ ruby19 -ce 'a(d,b.c +1)' -e:1: syntax error, unexpected tINTEGER, expecting ')' a(d,b.c +1)           ^ 14:53:50 $ ruby19 -ce 'a(b.c +1,e)' Syntax OK 14:53:55 $ ruby19 -ce 'a(d,b.c(+1))' Syntax OK 14:54:08 $ ruby19 -ce 'a((d,b.c)+1)' -e:1: syntax error, unexpected ')', expecting '=' a((d,b.c)+1)          ^ -e:1: syntax error, unexpected $end, expecting ')' 14:59:30 $ ruby19 -ce 'a(d,(b.c) +1)' Syntax OK It seems that 14:53:45 is parsed like 14:54:08 which is apparently is illegal because you also cannot do this: 14:54:16 $ ruby19 -ce '(a,b)' -e:1: syntax error, unexpected '\n', expecting '=' 14:58:18 $ ruby19 -ce '(d,b.c +1)' -e:1: syntax error, unexpected tINTEGER, expecting tCOLON2 or '[' or '.' (d,b.c +1)          ^ Hope that sheds some light. Kind regards robert > **···** > > On Tue, Nov 2, 2010 at 12:19 PM, Colin Bartlett \ wrote: > > > On Tue, Nov 2, 2010 at 7:17 AM, Robert Klemme \wrote: > > > > > Can you repost with proper indentation and line wrapping? > > > Guessing from your text I assume you might have fallen > > > into a unary / binary operator ambiguity. > > > > That seems to be a correct diagnosis. See below for the OP's irb session > > with formatting. > > For the OP: > > > > 7.abs + 3 #=\> 10 > > 7.abs+3 #=\> 10 > > > > 7.abs +3 #=\> ArgumentError: wrong number of arguments(1 for 0) > > ## Ruby parses the "+" in " +3" as a unary + on 3 giving integer 3, > > ## which means that integer 3 is an argument to abs, hence the error > > message. > > > > def okp( a, b ); a + b; end #=\> nil > > > > okp(4, 7.abs + 3) #=\> 14 > > okp(4, 7.abs+3) #=\> 14 > > okp(4, 7.abs +3) #=\> SyntaxError: (irb):23: syntax error, > > # unexpected tInteger, expecting ")" > > ## I leave that - and the next - one to Robert to explain! > > > > x = '123456' #=\> "123456" > > x.slice(1, x.size -2) #=\> SyntaxError: compile error(irb):63: > > # syntax error, unexpected ')', > > # expecting kDO\_BLOCK > > # from (irb):63 from :0 > > ## Again, the "-" in " -2" is parsed on a unary on 2 giving integer value > > -2. > > ## Why the ')' is unexpected I leave to Robert! > > -- > remember.guy do |as, often| as.you\_can - without end > [http://blog.rubybestpractices.com/](http://blog.rubybestpractices.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:** [2 November 2010 17:25 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/6 "2010-11-02T17:25:28Z")
> > > An issue pops up when I use a method's integer return value in a function argument while performing arithmetic on that value. Then missing whitespace between the arithmetical operator and the second argument can cause random errors, but only if there is whitespace preceding the operator. I don't want to rush to judgement and call this a bug, but it certainly seems like one, hidden till now because you have have formatting that's slightly ugly for the error to turn up. Here's an irb session that demonstrates the issue: > > > irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> xslice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0) f rom (irb):71:in `size' from (irb):71 from :0irb(main):072:0\> ok(4,x.size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):72 from :0irb(main):074:0\> ok(4,x.size + 3)=\> nil > > > > > > > Can you repost with proper indentation and line wrapping? Guessing > > from your text I assume you might have fallen into a unary / binary > > operator ambiguity. > > Sorry about that, Hotmail's "rich text" formatting messed it up I believe Here it goes again with plain text: > irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, xsize -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0 irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> x.slice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0 irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0 irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0)     from (irb):71:in `size' from (irb):71 from :0 irb(main):072:0\> ok(4,x.size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):72 from :0 irb(main):074:0\> ok(4,x.size + 3)=\> nil > Insert mode Not really... 🙂   robert > **···** > > On 02.11.2010 17:15, Ehsanul Hoque wrote: > > -- > remember.guy do |as, often| as.you\_can - without end > [http://blog.rubybestpractices.com/](http://blog.rubybestpractices.com/) ---
**Author:** ![Ehsanul\_Hoque](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@Ehsanul\_Hoque](https://rubytalk.org/u/Ehsanul_Hoque)\ **Post date:** [2 November 2010 20:24 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/7 "2010-11-02T20:24:20Z")
> \>\>\> An issue pops up when I use a method's integer return value in a function argument while performing arithmetic on that value. Then missing whitespace between the arithmetical operator and the second argument can cause random errors, but only if there is whitespace preceding the operator. I don't want to rush to judgement and call this a bug, but it certainly seems like one, hidden till now because you have have formatting that's slightly ugly for the error to turn up. Here's an irb session that demonstrates the issue: > \>\>\> irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> xslice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0) from (irb):71:in `size' from (irb):71 from :0irb(main):072:0\> ok(4,x.size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK from > (irb):72 from :0irb(main):074:0\> ok(4,x.size + 3)=\> nil > \>\>\> > \>\> > \>\> Can you repost with proper indentation and line wrapping? Guessing > \>\> from your text I assume you might have fallen into a unary / binary > \>\> operator ambiguity. > \> > \> Sorry about that, Hotmail's "rich text" formatting messed it up I believe Here it goes again with plain text: > \> irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, xsize -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0 irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> x.slice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0 irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0 irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0) from (irb):71:in `size' from (irb):71 from :0 irb(main):072:0\> ok(4,x.size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK > from (irb):72 from :0 irb(main):074:0\> ok(4,x.size + 3)=\> nil > \> Insert mode > > Not really... 🙂 > > robert You know what, I should probably just use pastie. Here you go: [http://pastie.org/1267606](http://pastie.org/1267606) Insert mode ---
**Author:** ![Justin\_Collins](https://avatars.discourse-cdn.com/v4/letter/j/3e96dc/32.png) [@Justin\_Collins](https://rubytalk.org/u/Justin_Collins)\ **Post date:** [3 November 2010 02:35 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/8 "2010-11-03T02:35:03Z")
Ehsanul Hoque wrote: >    > > > > > > An issue pops up when I use a method's integer return value in a function argument while performing arithmetic on that value. Then missing whitespace between the arithmetical operator and the second argument can cause random errors, but only if there is whitespace preceding the operator. I don't want to rush to judgement and call this a bug, but it certainly seems like one, hidden till now because you have have formatting that's slightly ugly for the error to turn up. Here's an irb session that demonstrates the issue: > > > > > irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> xslice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0) from (irb):71:in `size' from (irb):71 from :0irb(main):072:0\> ok(4,x. size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK from > > > > >            > > > > (irb):72 from :0irb(main):074:0\> ok(4,x.size + 3)=\> nil > >      > > > > > > Can you repost with proper indentation and line wrapping? Guessing > > > > from your text I assume you might have fallen into a unary / binary > > > > operator ambiguity. > > > >          > > > > > > Sorry about that, Hotmail's "rich text" formatting messed it up I believe Here it goes again with plain text: > > > irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, xsize -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0 irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> x.slice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0 irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0 irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0) from (irb):71:in `size' from (irb):71 from :0 irb(main):072:0\> ok(4, x.size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK > > >        > > > > from (irb):72 from :0 irb(main):074:0\> ok(4,x.size + 3)=\> nil > >      > > > > > Insert mode > > >        > > > > Not really... 🙂 > > > > robert > >      > > You know what, I should probably just use pastie. Here you go: [http://pastie.org/1267606](http://pastie.org/1267606) > > Insert mode >    > Robert was right. ok(x.size +3,4) is parsed as ok(x.size(+3, 4)) while you seem to be expecting ok((x.size + 3), 4)) Similarly with all your other examples. -Justin ---
**Author:** ![Ehsanul\_Hoque](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@Ehsanul\_Hoque](https://rubytalk.org/u/Ehsanul_Hoque)\ **Post date:** [3 November 2010 05:45 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/9 "2010-11-03T05:45:32Z")
---
**Author:** ![Justin\_Collins](https://avatars.discourse-cdn.com/v4/letter/j/3e96dc/32.png) [@Justin\_Collins](https://rubytalk.org/u/Justin_Collins)\ **Post date:** [3 November 2010 05:59 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/10 "2010-11-03T05:59:58Z")
Poorly. Also, I somehow missed Colin and Robert's answers, so I'll refer you to them. -Justin > **···** > > On 11/02/2010 10:45 PM, Ehsanul Hoque wrote: > > > ---------------------------------------- > >     > > > > > Date: Wed, 3 Nov 2010 11:35:03 +0900 > > > From: justincollins@ucla.edu > > > Subject: Re: Strange whitespace parsing behavior on Ruby 1.8.7 (patchlevel 249/302) > > > To: ruby-talk@ruby-lang.org > > > > > > Ehsanul Hoque wrote: > > >       > > > > > > > > > > > An issue pops up when I use a method's integer return value in a function argument while performing arithmetic on that value. Then missing whitespace between the arithmetical operator and the second argument can cause random errors, but only if there is whitespace preceding the operator. I don't want to rush to judgement and call this a bug, but it certainly seems like one, hidden till now because you have have formatting that's slightly ugly for the error to turn up. Here's an irb session that demonstrates the issue: > > > > > > > > irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> xslice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0) from (irb):71:in `size' from (irb):71 from :0irb(main):072:0\> ok(4,x.size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK from > > > > > > > > > > (irb):72 from :0irb(main):074:0\> ok(4,x.size + 3)=\> nil > > > > > > > > > > > > Can you repost with proper indentation and line wrapping? Guessing > > > > > > > from your text I assume you might have fallen into a unary / binary > > > > > > > operator ambiguity. > > > > > > > > > > > > Sorry about that, Hotmail's "rich text" formatting messed it up I believe Here it goes again with plain text: > > > > > > irb(main):062:0\* x = '123456'=\> "123456"irb(main):063:0\> x.slice(1, xsize -2)SyntaxError: compile error(irb):63: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):63 from :0 irb(main):064:0\> x.slice(1, x.size - 2)=\> "2345"irb(main):065:0\> x.slice(1, x.size-2)=\> "2345"irb(main):066:0\> x.slice(1, x.size -2)SyntaxError: compile error(irb):66: syntax error, unexpected ')', expecting kDO\_BLOCK from (irb):66 from :0 irb(main):067:0\> x[x.size -3,1]ArgumentError: wrong number of arguments (2 for 0) from (irb):67:in `size' from (irb):67 from :0 irb(main):068:0\> x[x.size - 3,1]=\> "4"irb(main):069:0\> def ok(a,b)irb(main):070:1\> end=\> nilirb(main):071:0\> ok(x.size +3,4)ArgumentError: wrong number of arguments (2 for 0) from (irb):71:in `size' from (irb):71 from :0 irb(main):072:0\> ok(4,x.size +3)SyntaxError: compile error(irb):72: syntax error, unexpected ')', expecting kDO\_BLOCK > > > > > > > > > > from (irb):72 from :0 irb(main):074:0\> ok(4,x.size + 3)=\> nil > > > > > > > > > > > Insert mode > > > > > > > > > > Not really... 🙂 > > > > > > > > > > robert > > > > > > > > You know what, I should probably just use pastie. Here you go: [http://pastie.org/1267606](http://pastie.org/1267606) > > > > > > > > Insert mode > > > > > > Robert was right. > > > > > > ok(x.size +3,4) > > > > > > is parsed as > > > > > > ok(x.size(+3, 4)) > > > > > > while you seem to be expecting > > > > > > ok((x.size + 3), 4)) > > > > > > Similarly with all your other examples. > > > > > > -Justin > > >       > > > That makes sense. But the inconsistency between the different behaviors given just a small difference in whitespace is still quite off-putting. > > > > Also how is this line parsed?: > > > > x.slice(1, x.size -2) > > > > - It seems unreasonable to parse it any way other than that intended.Insert mode ---
**Author:** ![Phil](https://avatars.discourse-cdn.com/v4/letter/p/e95f7d/32.png) [@Phil](https://rubytalk.org/u/Phil)\ **Post date:** [3 November 2010 08:20 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/11 "2010-11-03T08:20:02Z")
> That makes sense. But the inconsistency between the different behaviors given just a small difference in whitespace is still quite off-putting. One whitespace or an infinite number is rather irrelevant. A small difference to you is a world of difference for a computer. 😉 > Also how is this line parsed?: > > x.slice(1, x.size -2) > > - It seems unreasonable to parse it any way other than that intended. Computers can't read your mind. They do what you tell them, not what you mean. That results in you having to do the work of expressing your thoughts in terms the computer can actually understand and that are also logically correct. > **···** > > On Wed, Nov 3, 2010 at 6:45 AM, Ehsanul Hoque \ wrote: > > -- > Phillip Gawlowski > > Though the folk I have met, > (Ah, how soon!) they forget > When I've moved on to some other place, > There may be one or two, > When I've played and passed through, > Who'll remember my song or my face. ---
**Author:** ![Colin\_Bartlett1](https://avatars.discourse-cdn.com/v4/letter/c/dbc845/32.png) [@Colin\_Bartlett1](https://rubytalk.org/u/Colin_Bartlett1)\ **Post date:** [3 November 2010 15:07 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/12 "2010-11-03T15:07:13Z")
Subject to correction by Robert - or anyone else! - to summarise I think the basic problem for Ruby here is when to parse "-2" (without any space between the "-" and the "2") as a unary operator on 2 and as a binary operator on a previous "token" with 2 as the argument. At one extreme, Ruby could raise an error if there is any possible ambiguity. Ruby, I think, tries to do the best it can with \*limited\* knowledge of the methods being interpreted. For example:   7 -2 =\> 5 this works for a similar reason to the reason this works:   x = 13   x -2 #=\> 11 Ruby knows (or anyway interprets) x as a variable, not a method, so no ambiguity: the "-" is either a mistake or is a binary operator.   x.size #=\> 4   x.size-3 #=\> 1 I'm guessing that here Ruby "thinks" no whitespace, so bind the "-" to the first possible token, which is (x.size), so "-" gets treated as a binary operator. But in:   x.size -2 this could mean ((x.size) - 2) or (x.size( -2 )) In this case size doesn't take any arguments, so with some more work the interpreter could parse it as being likely to be ((x.size)-2), but that won't work for methods which can take zero or one (or more) arguments. So (again a guess) the idea is that the interpreter won't even try to to some extra work which might, or might not, resolve the ambiguity. The result is what seems to me to be a reasonable compromise, but I ought to add that some other possibilities might also be a reasonable (but different) compromise! > **···** > > On Wed, Nov 3, 2010 at 5:45 AM, Ehsanul Hoque \wrote: > > > That makes sense. But the inconsistency between the different behaviors > > given just a small difference in whitespace is still quite off-putting. > > > > Also how is this line parsed?: > > > > x.slice(1, x.size -2) > > > > - It seems unreasonable to parse it any way other than that intended.Insert > > mode ---
**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:** [3 November 2010 15:17 UTC](https://rubytalk.org/t/strange-whitespace-parsing-behavior-on-ruby-1-8-7-patchlevel-249-302/60692/13 "2010-11-03T15:17:50Z")
> > That makes sense. But the inconsistency between the different behaviors > > given just a small difference in whitespace is still quite off-putting. > > > > Also how is this line parsed?: > > > > x.slice(1, x.size -2) > > > > - It seems unreasonable to parse it any way other than that intended.Insert > > mode > > Subject to correction by Robert - or anyone else! - to summarise I think the > basic problem for Ruby here is when to parse "-2" (without any space between > the "-" and the "2") as a unary operator on 2 and as a binary operator on a > previous "token" with 2 as the argument. > > At one extreme, Ruby could raise an error if there is any possible > ambiguity. Ruby, I think, tries to do the best it can with \*limited\* > knowledge of the methods being interpreted. > > For example: > 7 -2 =\> 5 > this works for a similar reason to the reason this works: > x = 13 > x -2 #=\> 11 > Ruby knows (or anyway interprets) x as a variable, not a method, so no > ambiguity: the "-" is either a mistake or is a binary operator. I think the Ruby interpreter \_knows\_ it because during parsing it recognizes "x = 13" as a local variable assignment which makes x a local variable and will shadow method x (if it exists). That knowledge might also be used to disambiguate "x -2" which does not really make sens with a local variable if not interpreted as an expression with a binary "-". > x.size #=\> 4 > x.size-3 #=\> 1 > I'm guessing that here Ruby "thinks" no whitespace, so bind the "-" to the > first possible token, which is (x.size), so "-" gets treated as a binary > operator. > > But in: > x.size -2 > this could mean > ((x.size) - 2) or (x.size( -2 )) > In this case size doesn't take any arguments, so with some more work the > interpreter could parse it as being likely to be ((x.size)-2), but that > won't work for methods which can take zero or one (or more) arguments. > So (again a guess) the idea is that the interpreter won't even try to to > some extra work which might, or might not, resolve the ambiguity. > > The result is what seems to me to be a reasonable compromise, but I ought to > add that some other possibilities might also be a reasonable (but different) > compromise! Absolutely agree. I'd also like to add that this has never been an issue for me in practice. So we are probably putting something under a microscope which is actually really small. 🙂 Cheers robert > **···** > > On Wed, Nov 3, 2010 at 4:07 PM, Colin Bartlett \ wrote: > > > On Wed, Nov 3, 2010 at 5:45 AM, Ehsanul Hoque \wrote: > > -- > remember.guy do |as, often| as.you\_can - without end > [http://blog.rubybestpractices.com/](http://blog.rubybestpractices.com/)