Meaning of {} in ruby

This is probably the most tricky one - {} is also syntax for blocks, but only when passed to a method OUTSIDE the arguments parens.

When you invoke methods without parens, Ruby looks at where you put the commas to figure out where the arguments end (where the parens would have been, had you typed them)

1.upto(2) { puts 'hello' } # it's a block
1.upto 2 { puts 'hello' } # syntax error, ruby can't figure out where the function args end
1.upto 2, { puts 'hello' } # the comma means "argument", so ruby sees it as a hash - this won't work because puts 'hello' isn't a valid hash

Source: stackoverflow.com

Meaning of {} in ruby

When on their own, or assigning to a variable, [] creates arrays, and {} creates hashes. e.g.

a = [1,2,3] # an array
b = {1 => 2} # a hash
[] can be overridden as a custom method, and is generally used to fetch things from hashes (the standard library sets up [] as a method on hashes which is the same as fetch)
a = {1 => 2} # create a hash for example
puts a[1] # same as a.fetch(1), will print 2

Source: stackoverflow.com

Similar codes

0 vote306 views0 answer
Ruby
2 votes343 views1 answer
Rails mimemagic issue
Ruby
0 vote316 views0 answer
Ruby
2 votes407 views3 answers
Rails image tag
Ruby
1 vote382 views1 answer
Ruby non greedy regex
Ruby
0 vote345 views3 answers
Ruby raise error
Ruby
0 vote385 views1 answer
Ruby rails delete all of a model in console
Ruby
0 vote343 views1 answer
Rails localhost https
Ruby
0 vote306 views1 answer
Rails check routes in console
Ruby
0 vote341 views1 answer
Select tag . Default value rails
Ruby