Questions tagged [ruby-block]
37 questions
309
votes
10 answers
Blocks and yields in Ruby
I am trying to understand blocks and yield and how they work in Ruby.
How is yield used? Many of the Rails applications I've looked at use yield in a weird way.
Can someone explain to me or show me where to go to understand them?
Matt Elhotiby
- 43,028
- 85
- 218
- 321
138
votes
5 answers
Rails render partial with block
I'm trying to re-use an html component that i've written that provides panel styling. Something like:
43
votes
1 answer
Ruby: Use the return of the conditional for variable assignment and comparison
I have a method and in order to check whether it is being passed a block, I do the following:
if block_given?
res = yield(array[i], array[i+1])
else
res = array[i] - array[i+1]
end
However RuboCop is giving me a warning which I don't…
noloman
- 11,411
- 20
- 82
- 129
24
votes
4 answers
Why does Array#each return an array with the same elements?
I'm learning the details of how each works in ruby, and I tried out the following line of code:
p [1,2,3,4,5].each { |element| el }
And the result is an array of
[1,2,3,4,5]
Why is the return value of each the same array? Doesn't each just provide…
Jeff Storey
- 56,312
- 72
- 233
- 406
7
votes
1 answer
How to chain a method call to a `do ... end` block in Ruby?
I'm doing the following:
array_variable = collection.map do |param|
some value with param
end
return array_variable.compact
Can I call map and compact in one statement somehow, so I can return the result instantly?
I'm thinking on something like…
MattSom
- 2,097
- 5
- 31
- 53
7
votes
3 answers
Ruby - What are the differences between checking if block_given? and !block.nil?
I have a ruby method that needs to check if a block was passed to it.
A colleague is suggesting that simply checking if block.nil? is slightly faster in performance and works for named blocks. This is already quite annoying since he is using the…
singletony
- 1,392
- 1
- 9
- 9
6
votes
2 answers
How to check block is called using rspec
I want to check whether the block is called in my function using rspec. Below is my code:
class SP
def speak(options={},&block)
puts "speak called"
block.call()
rescue ZeroDivisionError => e
end
end
describe SP do
it "testing…
ojas
- 2,150
- 5
- 22
- 37
3
votes
2 answers
Pass a block to map function
I was wondering if something like this was possible?
info = arrange_info({|x| [x.name, x.number]}, info_array)
def arrange_info(block, info)
info.map(block).to_h
end
This would allow me to pass different blocks to arrange the array is…
user2320239
- 1,021
- 2
- 18
- 43
2
votes
1 answer
Ruby block as an array element for splatting in public_send
I am trying to build a generic method using meta programming where it uses manipulating methods from array and send to the object using splat, following is the working snippet:
ALLOWED_DATA_TYPES = {
'Integer' => [['to_i']],
'Csv' => [['split',…
Md. Farhan Memon
- 6,055
- 2
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- 36
2
votes
2 answers
Does `block_given?` render `&block` parameter optional?
I am comfortable with the following:
def some_def(foo, &block)
puts "block utilized below"
block.call(foo)
end
def some_other_def(bar)
puts "using yield below"
yield bar
puts "and back into the method"
end
So I have learned to…
foo
- 195
- 1
- 8
2
votes
4 answers
How can I chain with_index and with_object on an enumerable in ruby?
I want to process the array ['a', 'b', 'c'] to return the string '0a1b2c' (i.e, string formed by concatenating each index with its value).
I can do this:
result = ''
['a', 'b', 'c'].each.with_index do |char, i|
result += "#{i}#{char}"
end …
Anand
- 3,690
- 4
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- 64
1
vote
1 answer
Pass a method that receives args to another method that takes a block
I have some code that needs to be called directly or passed to another method that must take a block. Pseudocode:
class Foo
def bar
if condition
return method_that_needs_a_block!('string', named1:, named2:) do
shared_method('a',…
ryanpback
- 275
- 4
- 17
1
vote
1 answer
Optional explicit block parameter in Ruby?
As noted in the comments, the question is actually the answer.
If the method gets a block, I want to use it further. But I also have a variant where the block isn’t needed. Can I do this in any way?
For example:
def maybe_gets_block(&blk)
if blk
…
user13775669
1
vote
0 answers
Unable to set the node attributes within a ruby block
I have exactly the same code as suggested in the given link by @StephenKing (https://stackoverflow.com/users/400222/stephenking) and although the command works and gives the correct return value (verified using log/print) the value is not set in the…
blueowl
- 35
- 6
1
vote
1 answer
Get the name of the currently if condition declaration
I was wondering if it was possible to pass as parameter the if condition statement as string or symbol. Because method name or if statement name could change and if I need it to refacto things it's better to work with a variable,
here an example…
v2lrf
- 321
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- 8