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I'm getting familiar with ruby send method, but for some reason, I can't do something like this
a = 4
a.send(:+=, 1)
For some reason this doesn't work. Then I tried something like
a.send(:=, a.send(:+, 1))
But this doesn't work too. What is the proper way to fire plus equals through 'send'?
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Assignment Operators (==, +=, ||=) These are equivalent to reading the current value & using one of the arithmetic operators with it, then saving the result. You can do this with all the arithmetic operators, including the modulo operator ( % ). But there are two assignment operators that behave in a different way!
The :: is a unary operator that allows: constants, instance methods and class methods defined within a class or module, to be accessed from anywhere outside the class or module. Remember in Ruby, classes and methods may be considered constants too.
send is a Ruby method allowing to invoke another method by name passing it any arguments specified. class Klass def hello(*args) "Hello " + args.join(' ') end end k = Klass.new k.send :hello, "gentle", "readers" #=> "Hello gentle readers" Source.
Send method basics Typically dot notation is used to a call method on an object. In the code snippet just below, on line 2 the + method is called on the integer object. The send method works similarly to dot notation. The send method invokes the method identified by symbol, passing it any arguments specified.
I think the basic option is only:
a = a.send(:+, 1)
That is because send is for messages to objects. Assignment modifies a variable, not an object.
It is possible to assign direct to variables with some meta-programming, but the code is convoluted, so far the best I can find is:
a = 1
var_name = :a
eval "#{var_name} = #{var_name}.send(:+, 1)"
puts a # 2
Or using instance variables:
@a = 2
var_name = :@a
instance_variable_set( var_name, instance_variable_get( var_name ).send(:+, 1) )
puts @a # 3
See the below :
p 4.respond_to?(:"+=") # false
p 4.respond_to?(:"=") # false
p 4.respond_to?(:"+") # true
a+=1 is syntactic sugar of a = a+1. But there is no direct method +=. = is an assignment operator,not the method as well. On the other hand Object#send takes method name as its argument. Thus your code will not work,the way you are looking for.
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