Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
931 views
in Technique[技术] by (71.8m points)

ruby - Why is this not a syntax error?

If I do this:

(false true)

it fails with a syntax error, as I expect. But if I do this:

(false
 true)

the code is executed, and it throws away the first condition and returns the result of the second.

Is this considered a bug or a feature?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

Line endings are optional, so in this case, the return is causing the parser to interpret it as the following:

(false; true)

which evaluates to just:

(true)

If these were method calls then both would be evaluated, but only the last would be emitted. For example:

x = (p "hello"
p "world"
2)

This will output "hello" and "world" and x will equal 2


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...