My requirements are that control needs to remain with applications to
provide feedback about any of a _variety_ of actions a program may be
*doing* -- not simply how long a user has been waiting.  Changing the
cursor form is already process-intensive enough without needing to
endure any more performance degradation, please.

I struggle to understand why, for any package that thinks it wants to
do something graphical like operate on a Cursor, should not depend on
the Graphics package anyway?  Why so worried to the point of getting
away from simple OO sending a message to the Form object and moving to
some kind of relational lookup simply because of a valid package
dependency..?

If we MUST sterilize the system, Frank seems to have the best
compromise with performance so far with the CASE statement.
Unfortunately it still chips away at the simplicity and also
functionality we have now, such as the ability for an application to
conveniently extend with its own cursor forms.  Is it about "feeling
squeaky clean," or is there some bigger payoff I'm missing?  Is this
about getting to a smaller core?


On Mon, Jun 24, 2013 at 12:43 PM, Frank Shearar <frank.shearar at gmail.com> wrote:
> On 24 June 2013 18:30, tim Rowledge <tim at rowledge.org> wrote:
>>
>> On 24-06-2013, at 5:31 AM, Frank Shearar <frank.shearar at gmail.com> wrote:
>>>  You would then write:
>>>
>>>    UIManager default showCursor: #wait during: ["stuff"]
>>
>>> snip]
>>
>>> The reason for the icky reflection is to fit in with the existing way
>>> cursors are used. I'd be happy to unroll the #perform: into a #caseOf:
>>> mapping explicitly to the existing cursors.
>>>
>>> Thoughts
>>
>> Well I really dislike seeing #respondsTo: et al in general code so I'd propose something along the lines of a list of known cursors (it's reasonable in my opinion to make that list using reflection at either startup or add-new-cursor time) and then
>>
>> Cursor class >> #named: aSymbol
>>    ^  cursorList at: aSymbol ifAbsent:[self normal]
>
> Yep, reflection hides the actual API, and makes things slow as well.
> So in Cursor's particular case, it has loads of classvars with names
> of the form FooCursor, Foo naturally corresponding to the selector
> #foo. So there's CrossHairCursor, BlankCursor, etc. That means you end
> up duplicating the list of cursors (between the set of class vars and
> cursorList), or you make a rather invasive change of ripping out all
> the class vars. A middle ground might be this:
>
> Cursor >> named: aSymbol
>     ^ aSymbol caseOf: {
>        [#down] -> [self down].
>         [#wait] -> [self wait].
>     } otherwise: [self normal].
>
> frank
>
>> tim
>> --
>> tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
>> Strange OpCodes: CCC: Crash if Carry Clear
>>
>>
>>
>