DDevelopment & Design

Commitment in ScrumCommitment in Scrum

Short note taken long time ago from Henrik Kniberg’s slides about a few aspects of commitment in Scrum

This is a note to self. Note taken long ago from Scrum beyond trenches slides by Henrik Kniberg. Just for myself not to forget.

The sprint commitment – misconceptions

”We promise to achieve this goal”
“We promise to deliver all stories included in the sprint backlog”

I’ll repeat!. These are misconceptions!

 Team’s commitment to the product owner

We promise that:

“… we believe we can reach the sprint goal.”
“… we will do everything in our power to reach the sprint goal, and will let you know immediately if we no longer believe we can reach it.”
“… we believe that we can complete all stories included in the sprint backlog.”
“… we will demonstrate releasable code at the end of the sprint.”
“… if we fall behind schedule we will talk to you and, if necessary, remove the lowest priority stories first.”
“… if we get ahead of schedule, we will add stories to the sprint from the product backlog, in priority order.”
“… we will display our progress and status on a daily basis.”
“… every story that we do deliver is Done.”

Hmm, the opposite of misconceptions should be conceptions, right :D?

Your experience

Would you add any more to these lists? Do you have any experience being hit by wrongly understood commitment? Share!

Kiedyś programista, obecnie PM i ewangelista metod zwinnych.

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DDevelopment & Design

Private fields and methods are not private in groovy

I used to code in Java before I met groovy. Like most of you, groovy attracted me with many enhancements. This was to my surprise to discover that method visibility in groovy is handled different than Java!

Consider this example:

class Person {
private String name
public  String surname

private Person() {}

private String signature() { "${name?.substring(0, 1)}. $surname" }

public String toString() { "I am $name $surname" }
}

How is this class interpreted with Java?

  1. Person has private constructor that cannot be accessed
  2. Field "name" is private and cannot be accessed
  3. Method signature() is private and cannot be accessed

Let's see how groovy interpretes Person:

public static void main(String[] args) {
def person = new Person()   // constructor is private - compilation error in Java
println(person.toString())

    person.@name = 'Mike'       // access name field directly - compilation error in Java
println(person.toString())

    person.name = 'John'        // there is a setter generated by groovy
println(person.toString())

    person.@surname = 'Foo'     // access surname field directly
println(person.toString())

    person.surname = 'Bar'      // access auto-generated setter
println(person.toString())

println(person.signature()) // call private method - compilation error in Java
}

I was really astonished by its output:

I am null null
I am Mike null
I am John null
I am John Foo
I am John Bar
J. Bar

As you can see, groovy does not follow visibility directives at all! It treats them as non-existing. Code compiles and executes fine. It's contrary to Java. In Java this code has several errors, pointed out in comments.

I've searched a bit on this topic and it seems that this behaviour is known since version 1.1 and there is a bug report on that: http://jira.codehaus.org/browse/GROOVY-1875. It is not resolved even with groovy 2 release. As Tim Yates mentioned in this Stackoverflow question: "It's not clear if it is a bug or by design". Groovy treats visibility keywords as a hint for a programmer.

I need to keep that lesson in mind next time I want to make some field or method private!