Ted Naleid

So groovy has this cool operator called the “spread” operator: “*.”.

Right now, it’s listed as the top hidden feature of Groovy over on StackOverflow. It works like this:

[1, 2, 3, 4]*.toString() 
// equals ["1", "2", "3", "4"]

It applies the method/property to the right of the operator to each member of the collection and returns the results as another collection. It’s syntactic sugar for doing this:

[1, 2, 3, 4].collect { item -> item.toString() }

(and that’s syntactic sugar for a whole pile of Java code :)

Did you know that for properties, you don’t actually need to use the spread operator? Neither did I till I fat-fingered a command working with a list of Grails domain objects and it still worked.
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1 Comment » Posted by tednaleid / grails and groovy

In my current project, I’ve been doing a lot of tweaking of the default grails scaffolding templates. Because of this, I need to run the new uber generate-all command quite a bit to recreate things.

The one problem with this script is that if the files already exist, a prompt will come up after ~10 seconds or so (after the grails environment bootstraps) asking you if you want to Overwrite everything:

grails generate-all "*" 
...
~10 seconds pass
...
Generating views for domain class Baz ...
File /foobar/grails-app/views/baz/list.gsp already exists. Overwrite?y,n,a

This was a bit of a pain as I’d often kick the script off, get distracted and then come back to the shell with that prompt still waiting for me to tell it what to do. I’d rather just start working with my shiny new scaffolding.

The easy solution to this is simply to pipe the answer you want into the grails command:

echo "a" | grails generate-all "*"

Doing that will pipe the “a” into the grails command so that when the prompt finally comes up, it knows that it can continue regenerating all of my scaffolding.

It seems simple enough after I figured it out, but I thought it could save some other people time when they’re hacking around with templates and know they want to regenerate all of them.

No Comments » Posted by tednaleid / command line and grails and groovy and osx and shortcut

Out of the box, groovy gives you a number of powerful methods to iterate over lists and maps:

def fibList = [1, 1, 2, 3, 5]
 
fibList.each { println it }  // prints all of the numbers in the list
assert fibList.any { it == 3 }
assert fibList.every { it > 0 }
assert fibList.collect { it - 1 } == [0, 0, 1, 2, 4]
assert fibList.findAll { it > 1 && it < 5 } == [2, 3]
assert fibList.find { it > 1 } == 2
assert fibList.inject("fib: ") { str, val -> str << val }.toString() == "fib: 11235"

That’s really nice if you’re working with raw lists and maps, but what if you have a class that doesn’t extend list or map? How hard is it to empower that class with the groovy iteration methods? If this were Java, you’d likely need to implement an interface with these methods (and throw a “not implemented” exception for those you didn’t feel like taking the time to implement).

Since it’s not Java, but groovy (and you’ve read the title of this blog post :), you know it’s easy!
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7 Comments » Posted by tednaleid / grails and groovy and shortcut