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Re: Problems with ChoiceDialog inside a Dynamic: Bug or not (well) documented limitation?

• To: mathgroup at smc.vnet.net
• Subject: [mg107786] Re: [mg107725] Problems with ChoiceDialog inside a Dynamic: Bug or not (well) documented limitation?
• From: Guido Tripaldi <guido at gtripaldi.it>
• Date: Fri, 26 Feb 2010 04:05:06 -0500 (EST)
• References: <201002250649.BAA20530@smc.vnet.net> <4B86A306.9020402@wolfram.com>

Thank you Adam! Problem solved!

I would like to propose two improvements in the Documentation Center: 
the first is to add the possibility to add custom comments in the 
functions/commands help pages (where to store, for example, the 
suggestions, like this, found in the user group, some personal sample 
code, etc). The second, similar but different, is to add a section in 
the help pages with a view to a sort of wiki where every mathgroup users 
can add samples, comments and explanations tagged for relevants 
functions/commands. This would make it possible to always have readily 
available the maximum information for each command.

Cheers,
   G


Il giorno 25/feb/2010, alle ore 17.19, Adam Griffith ha scritto:

> ChoiceDialog[] blocks the kernel evaluation until it is closed. 
Therefore you could do something like:
>
> TabView[{"Tab1" ->   Button["Show ChoiceDialog",    result = 
ChoiceDialog["This holds eval.. :-)."],    Method -> "Queued"],  "Tab2" 
->   Button["Show MessageDialog", MessageDialog["This works!"];]}]
>
> -Adam
>
>
>
>
>
> Guido Tripaldi wrote:
>> Hi Group,
>> suppose you wanna to display an alert to the user before to continue 
the execution of your code when some conditions occur : probably you'll 
use ChoiceDialog[], the useful function that "puts up a standard choice 
dialog that displays  expr together with OK and Cancel buttons, and 
returns  True if OK is clicked, and  False if Cancel is clicked.".
>>
>> But if you use this function inside some Dynamic[] object, it hangs 
the kernel. I've tried to find in the documentation some references to 
this bad combination without any luck, so I don't understand if this is 
a bug or there is something missing in the code.
>>
>> To better explain the problem here is a very basic example:
>>
>> (* just a silly example *)
>> Grid[{
>>  {"Choose a dividend: ",
>>   PopupMenu[Dynamic[dividend], Table[i, {i, 0, 10}]]},
>>  {"Choose a divisor : ", PopupMenu[Dynamic[divisor], Table[i, {i, 0, 
10}]]},
>>  {"Quotient: ", Dynamic[dividend / divisor]}
>>  }, Frame -> All]
>> Dynamic[
>> If[divisor == 0,
>>   ChoiceDialog["Uh-oh, you are going to do a division by zero! Please 
select a different divisor.", {"Ok"}];
>> ]];
>>
>> Instead, if you use the MessageDialog[] function to show a message 
window, all works well, but of course the execution will continue 
without waiting for the user action (that is not what I want).
>>
>> Same situation if you try to use ChoiceDialog[] inside a TabView, or 
other kind of Views:
>>
>> (* another silly example *)
>> TabView[{
>>  "Tab1" -> Button["Show ChoiceDialog", result = ChoiceDialog["This 
hangs.. :-(."];],
>>  "Tab2" -> Button["Show MessageDialog", MessageDialog["This 
works!"];]
>>  }]
>>
>>
>> Any suggestion?
>> thanks!
>>   G
>>
>> ps
>> M7.0.1.0 on Mac Snow 10.6.2
>>
>> ---
>> Guido Tripaldi
>>
>>
>> 
>

---
Guido Tripaldi
imho.gtripaldi.it

• References:
  • Problems with ChoiceDialog inside a Dynamic: Bug or not (well) documented limitation?
    • From: Guido Tripaldi <guido@gtripaldi.it>