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Closed 11 years ago.
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Double colons rails
What does :: do?
I was reading a manual on Rails and came across this snippet:
match 'rocketeer.js' => ::TestRoutingMapper::RocketeerApp
I'd never seen the :: syntax at the head of a class name before. I'm wondering what is the significance of writing it this way.
See my answer to What does :: do?
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What does map(&:name) mean in Ruby?
(17 answers)
Closed 12 months ago.
This is from a solution I saw at a competitive programming site:
gets.split.map &:to_i
The &:to_i phrase seems to be equivalent to {|s| s.to_i}, but I can't find anything about that syntax at ruby-doc.org, or a match for "&:" [ruby] here. (I don't know what to call it for an English language search, either.)
If it matters, that site is using Ruby 3.0.1.
It's an example of Symbol#to_proc - see https://www.brianstorti.com/understanding-ruby-idiom-map-with-symbol/ for a more detailed explanation, or the ruby API documentation
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What does the '-' (dash) after variable names do here?
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Usage of :- (colon dash) in bash
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Closed 2 years ago.
ENV=${deploy-qa}
echo $ENV
qa
Relatively new to bash and I'm trying to set up a pipeline that switched based off the ending of a string and accidentally stumbled across this. I'm unsure how this actually returns 'qa' though. This is what I was looking to do, but I'd like to understand what's actually happening. I dont understand whats causing the 'deploy-' bit to drop off.
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What does an underscore and interface name after keyword var mean?
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Closed 4 years ago.
Little bit confused with this code.
var _ QueryAppender = (*selectQuery)(nil)
I found this code in pg-go
repository and don't know why QueryAppender declared that way. Please explain me what is the use cases when I should declare variables that way.
This doesn't do anything at runtime, but unless the *selectQuery type satisfies the interface QueryAppender, compilation will fail. It's a kind of static assertion.
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How to call a static method in JSP/EL?
(9 answers)
Closed 5 years ago.
Is there any way to provide space between Capital Letters.
Eg. I have a jstl expression ${platName} which outputs AmazonEcho
What I need as output is Amazon Echo.
I tried a few jstl functions but it didn`t help.
Thanks, this worked
${platName.replaceAll("(\\p{Ll})(\\p{Lu})","$1 $2")}
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Split string into equal slices/chunks
(2 answers)
Closed 7 years ago.
I was wondering how I could program something to split a string into blocks of five using Ruby. Help much appreciated.
You can use String#scan method to achieve it. E.g 'string_test'.scan(/.{1,5}/)