DDevelopment & Design

Context menu or Action buttons ?

Recently I was drawn into one of those UI “religious” disputes that has no easy answers and usually both sides are right. One of our web developers was trying out new web tech (with pretty rich widget library) and started to question himself about some basic usability decisions. The low level problem in this case is usually brought to “which widget should I use ?”. I’m not fond of bringing the usability problems to questions: Should I use Tabs over Menu ? Or should I use Context menu instead of buttons panel ? But sometimes if time is crucial factor and other usability levels are by default not addressed at all – better developer that asks those basic questions than developer that do not question himself at all.

Recently I was drawn into one of those UI “religious” disputes that has no easy answers and usually both sides are right. One of our web developers was trying out new web tech (with pretty rich widget library) and started to question himself about some basic usability decisions. The low level problem in this case is usually brought to “which widget should I use ?”. I’m not fond of bringing the usability problems to questions: Should I use Tabs over Menu ? Or should I use Context menu instead of buttons panel ? But sometimes if time is crucial factor and other usability levels are by default not addressed at all – better developer that asks those basic questions than developer that do not question himself at all. One of often “problematic” choice that is bring up by web developers is should user launch actions on selected objects (one of many or some of many) by “Context menu” or “Action buttons”. Basic example is shown below and it is usually a table or list of components that has some defined actions (i.e. on table where rows are single orders change status of selected order would be on of possible actions). Of course there are many other solutions that can be implemented (some actions can be handled directly in table row or cell) but narrowing choice to those two was subject of mentioned discussion. During those hot and fast discussions I wasn’t able to point out pros and cons of both solution that’s why I decided to grab them all in this one short post. I hope it will be helpful for same lone developers that thirstily look for best practise or choice while the answer is usually much contextual…

Action button panel

example_view_1

(plus) Pros

  • Clear indication of where and how many actions you can apply to selected row (or other selected object)
  • If action panel is visible all the time theme has expectable behaviour (at least if you are consistent at where you position your action panel)
  • Accessible solution on most mediums (mouse, touch screens, other pointing devices), panel can be bookmarked to be heard on reading devices
  • Action panel can be combined with Details panel (if there is enough space)
  • Actions can be described very precisely

(minus) Cons

  • Space consumption, even if some actions can be hidden under “Advanced” button, this design is always more “stuffed”
  • Can generate (sometimes really long) extra mouse moves and additional clicks
  • Keyboard support may be difficult if rows or selected widgets also use navigations buttons (tab key, arrows etc.)

Context menu

{#Test-Contextmenu}

example_view_2

(plus) Pros

  • If you stick to short action names space consumption is minimal and since it’s used only during action selection it’s also less perceptible
  • Much faster if you use mouse or keyboard (with context menu shortcut / button)
  • Actions can be organised in tree like hierarchy which can be navigated (expanded) with minimal mouse moves and no additional mouse clicks
  • Nicely combines with drag&drop or multi record actions

(minus) Cons

  • Since context menu is invisible until explicitly called some people may not be aware that there are any actions available on selected objects
  • Poor support on some touch pads or touch screens, problematic support on screen readers
  • If used in web applications it overrides default browser context menu which can be a nuisance for some users

Why not both ?

{#Test-Whynotboth%3F}

example_view_3

(plus) Pros

  • Beginners has clear indication of where and what actions are available on selected objects
  • Advanced users can use faster context menu approach, that do not confuse beginners (they still has their action buttons)
  • Action buttons panel can be compressed to minimum, only to show most important actions (other actions can be hidden under “Advanced” button)
  • Action panel can be combined with Details panel, since action buttons would be minimal, there should be more space for details
  • Hide action panel option if workspace size is crucial (i.e. some clients has limited screen size) and users are aware of context menu

(minus) Cons

  • Initially you still loose some fix space
  • Redundancy may be confusing for some users (although this con is questionable – unaware beginners do not see any redundancy, advanced users can hide action panel if it REALLY bothers them)

Summary Choice between Context menu or Action buttons panel is pretty contextual and “right” choice strongly depends on supported media and user group. However there is pretty good “mix” solution that gives more pros than cons (unless redundancy is big problem for you) and will satisfy unaware beginners and users that strives for fast actions. If you come to mentioned choice, always give a chance to “why not both ?” scenario.

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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!