Private GUI Callbacks and SKILL++

The callbacks are evaluated in the global scope, so that's why it can't see your lexically scoped callback function. From IC617 onwards, you can specify most of the UI callbacks as function objects rather than a SKILL expression or the name of a function, so that allows you to pass the function object accessed via a lexical scope to be the callback - and then since the UI now has the function object, it will be called in the correct scope.

Details on how to specify function objects as callbacks can be found in the Cadence User Interface SKILL Reference manual, in Chapter 1, in a section headed Function Object Callbacks.

Here's a simple example I just put together based on your outline:

; ensure this is in a file with a .ils suffix
myPackage=let(()
  procedure(createGUI()
    hiDisplayForm(
      hiCreateAppForm(
	?name 'forumGUI
	?fields
          list(
            list(
              hiCreateStringField(
                ?name 'name 
                ?prompt "Name"
              )
              0:0 400:30 100)
            list(
              hiCreateButton(
                ?name 'button
                ?buttonText "Press me"
                ; pass the callback as a function object rather than
                ; the name of the function or a SKILL expression
                ?callback buttonCB
              )
              100:30 150:30)
          )
      )
    )
  )
  procedure(buttonCB(field scope)
    printf("Button pressed - field:%L scope:%L\n"
      field scope
    )
  )
  list(nil 'createGUI createGUI)
)

Regards,

Andrew.

Perfect!  Got it working.  Thanks!

Is there a way to make the deRegApp callbacks private?  Can I use a function object as the callback there also?

-Curtis

Hi,

Once all questions of Curtis are answered, I would like to understand how loading this file in SKILL++ context helps here. What is the we have achieved here by going for SKILL++ instead of just SKILL?

I have read Jim Newton's SKILL++ blog but still I miss something. Any help here?

-Ramakrishnan

Also, is there a way to declare a file to be read as skill++ without setting the extension.  Specifically I'm thinking about situations lwhere we don't have the option to change the file name.  For example, can we use SKILL++ in the .cdsinit or the library manager init file.  

Should I just include toplevel( 'ils ) at the top of my .cdsinit file to get it to use SKILL++?

Here I am trying to encapsulate my code so only a well-defined interface is made public.  This allows me to hide implementation details and avoids cluttering the top-level namespace.  SKILL++ also enables the use of an object-oriented programming methodology with the SKILL++ object system.  This can be used to improve the maintainability of the code and encourages reuse of code.  SKILL++ brings some modern software engineering techniques to SKILL.  

Now if only there was some type of testing framework and a modern IDE...

Curtisma said:

Is there a way to make the deRegApp callbacks private?  Can I use a function object as the callback there also?

Hi Curtis,

No. These callbacks currently have to be specified as the symbol for the name of the function. There may well be an enhancement request to change this (I didn't check as I'm on vacation this week), but it would be worth you contacting customer support to request this.

Regards,

Andrew.

For Ramakrishnan - one of the key benefits (other than the object system) is that SKILL++ provides lexical scoping rather than SKILL's dynamic scoping. That then enables local functions (so a function defined within a surrounding let is not visible outside by default) - and you can share private data between multiple functions in the same lexical scope. This allows creation of closures, packages and so on.

There is an IDE (a relatively recent addition - it's got a lot better in recent versions). Not as advanced as some IDEs for other languages, maybe, but a step in the right direction. As for testing frameworks, it's reasonably easy to build your own of course...

Regards,

Andrew.

Curtisma said:

Should I just include toplevel( 'ils ) at the top of my .cdsinit file to get it to use SKILL++?

You can't just put toplevel('ils) at the top of your file - that won't work. You can surround your code with inScheme() though:

inScheme(
  ; your SKILL++ code sitting in a file read with SKILL semantics
)

Similarly there's an inSkill macro for the opposite.

Regards,

Andrew.

Andrew:

I assume your team some sort of SKILL testing framework.  Do you have anything you can share so I don't have to reinvent the wheel? If not, any suggestions on starting one?

-Curtis