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I am just learning Ruby and I want to know the difference between

a += b

and

a =+ b
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    It makes sense, because it is a beginner question. At a guess, the asker saw this in someone else's code (which is why smartypants, non-standard code is rarely a good idea!). Commented Aug 22, 2017 at 10:05

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  1. a += b is syntactic shorthand for a = a + b
  2. a =+ b is similar to a = + b

So, firstValue = firstValue + secondValue is the same as firstValue = firstValue.+(secondValue) in ruby. firstValue + = secondValue – increment Add the value of secondValue to the value of firstValue , store the result in firstValue, and return the new value.

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4
  • foo += bar is shorthand for foo = foo + bar.
  • foo =+ bar is an unusual way to write foo = +bar.
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2 Comments

It’s worth to mention that for the latter to work, the +@ instance method should be defined on bar.class. For the former, the coercion from bar.class to foo.class is required.
An actual use case: if bar is a frozen string, then foo = +bar becomes a shorthand for foo = bar.dup, i.e. it assigns a mutable duplicate of the string to foo.

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