programming matrix: January 2020

Tuesday, January 28, 2020

git checkout master
git pull
git checkout mobiledevicesupport
git merge master

a single test can be ran by running, in sbt,

testOnly *class -- -n Tag

to run only the tests whose name includes the substring "foo".

testOnly *MySuite -- -z foo

For exact match rather than substring, use -t instead of -z.

val symTab = collection.mutable.HashMap[String, Int]()
def update0(s: String): Unit = {

if (symTab.contains(s)) {

symTab(s) = symTab(s) + 1

}

else {

symTab(s) = 1

}

// Do this instead

def update1(s: String): Unit = symTab(s) = symTab.getOrElse(s, 0) + 1

scala> update1("x")

scala> symTab("x")

res2: Int = 1

scala> update1("x")

scala> symTab("x")

res4: Int = 2