Confusion with setter method

Ruby
1

C:>irb --simple-prompt
DL is deprecated, please use Fiddle

class A
def property= value
x, y = value
p value
end
end
=> nil

A.new.property= 1,2
[1, 2]
=> [1, 2]

A.new.property = 1,2
[1, 2]
=> [1, 2]

A.new.property =(1,2)
SyntaxError: (irb):9: syntax error, unexpected ‘,’, expecting ‘)’
A.new.property =(1,2)
^
from C:/Ruby200/bin/irb:12:in `’

A.new.property=(1,2)
SyntaxError: (irb):10: syntax error, unexpected ‘,’, expecting ‘)’
A.new.property=(1,2)
^
from C:/Ruby200/bin/irb:12:in `’
==========================================================================

I am on below version:

C:>ruby -v
ruby 2.0.0p0 (2013-02-24) [i386-mingw32]

Questions:

(a) How does without splat operator value took 1,2?
(b) Why did A.new.property= 1,2 work well,but A.new.property= (1,2)
not?

2

Because [1,2] is one argument, and (1,2) is two arguments.

3

That’s not the reason.

4

On 29/03/2013, at 5:58 AM, Love U Ruby [email protected] wrote:

[1, 2]
SyntaxError: (irb):10: syntax error, unexpected ‘,’, expecting ‘)’

Questions:

(a) How does without splat operator value took 1,2?
(b) Why did A.new.property= 1,2 work well,but A.new.property= (1,2)
not?

–
Posted via http://www.ruby-forum.com/.

Ruby syntax can be relaxed. This is a good and bad thing. It’s powerful,
but it requires that you know what you’re doing.

Ruby can only interpret A.new.property=(1,2) as a call to a method
“property=” that has two arguments, but you have no such method. Your
method only takes one argument. So, you get a syntax error.

However, Ruby can interpret A.new.property= 1,2 as either a call to a
method with one or two arguments, so it tries to do the right thing.
The more explicit version of this call is A.new.property= [1,2] or for
the most explicit version: A.new.property=([1,2])

Intent is incredibly important, so it’s good to explain your intent in
each case when you write code you want explanations for. Just putting
code up won’t signal your intent in each case, or what you think is
going to happen. It’s good to note both when asking for help.

5

I’d suggest you explain that, because that IS the reason, based on the
shown code. If you disagree, you’ll have to do more than say its not the
reason and not say anything else.

6

Julian L. wrote in post #1103593:

On 29/03/2013, at 5:58 AM, Love U Ruby [email protected] wrote:

Ruby syntax can be relaxed. This is a good and bad thing. It’s powerful,
but it requires that you know what you’re doing.

Ruby can only interpret A.new.property=(1,2) as a call to a method
“property=” that has two arguments, but you have no such method. Your
method only takes one argument. So, you get a syntax error.

However, Ruby can interpret A.new.property= 1,2 as either a call to a
method with one or two arguments, so it tries to do the right thing.
The more explicit version of this call is A.new.property= [1,2] or for
the most explicit version: A.new.property=([1,2])

Nice explanation,I understood. :slight_smile: