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 vote376 views1 answer
Or even multiple scope parameters. For example, making sure that a teacher can only be on the schedule once per semester for a particular class.
Ruby
0 vote381 views2 answers
Check validate url ruby
Ruby
6 votes535 views1 answer
Contains ruby array
Ruby
0 vote375 views1 answer
I am working in ruby 2.6 how to jump to a lower version
Ruby
0 vote362 views1 answer
Replacing consecutive numbers with dash between first and last in a range
Ruby
0 vote341 views1 answer
Devise generate controller
Ruby
0 vote333 views1 answer
How to reset migrations rails
Ruby
0 vote356 views1 answer
Rails not_found
Ruby
0 vote356 views1 answer
Rails form_tag
Ruby
0 vote350 views1 answer
Rails g migration foreign key optionnal
Ruby