Beginners November 2009

beginners@lists.squeakfoundation.org

40 participants
37 discussions

Building a remote count down clock
by Andy Burnett 08 Nov '09

08 Nov '09

Hello I want to build a count down clock that will be used for presenters at an upcoming conference. The important point is that the clock needs to be started and stopped by the 'admin' guy, but displayed on one or more screens for the speaker. My initial thought was to do it in seaside. However, I then wondered whether it would be better to build it all in Squeak. The benefit of the Squeak approach (I am guessing) is that I could somehow broadcast to the listening images that I wanted them to start/stop, rather than have them polling every second. Obviously, the app is tiny, so in practical terms it doesn't matter either way, but I am now curious about how I might communicate the start/stop messages over the network to the images. Is this relatively easy in Squeak? cheers Andy

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Re: Building a remote countdown clock
by Andy Burnett 08 Nov '09

08 Nov '09

Herbert said << no, you haven't. I used the code in a network with fixed IP's and no DHCP running. Right here using NetNameResolver works just fine. If you doIt: (NetNameResolver addressForName: 'aComputersName') inspect you should get an Inspector on a ByteArray with the IP address. >> Hmmm, I was expecting to get an inspector on a ByteArray, but what I actually got was an inspector on SocketAddress. Something is obviously not quite right here! :-)

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isStepping question
by Christine Wolfe 07 Nov '09

07 Nov '09

If I have a morph that is stepping through some process I know I can test for whether or not it is still stepping by using the isStepping method. But, how to I put this into a loop so that the next instruction doesn't start until the stepping is done. Here is my mouseDown code. I want to put something in before the last instruction so it doesn't execute until isStepping becomes false. mouseDown: evt path := OrderedCollection new. 0 to: 9 do: [:i | path add: self position + (0@(10 * i))]. path := path, path reversed. self startStepping. self owner moveTheGameBall.

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Re: Building a remote countdown clock
by Andy Burnett 07 Nov '09

07 Nov '09

David Corking said << > > Andy, > > RFB (VNC) is quite popular in Squeak and may do what you want. > > I haven't used Nebraksa, but as far as I can tell it solves the > distribution problem for you - if you want to build the UI in Morphic > or MVC. > > http://wiki.squeak.org/squeak/1356 > > According to this ticket Nebraska is broken in recent Etoys releases > https://dev.laptop.org/ticket/7745 (I don't know about its state in > mainstream Squeak images, so you may prefer to go to an older Squeak, > or use Socket directly as Herbert suggested.) > > Hope that helps, David > > >> > Thanks David, I have never heard of the Nebraska system. It looks very interesting. I will have a go with it. Cheers Andy

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Re: Building a remote countdown clock
by Andy Burnett 07 Nov '09

07 Nov '09

Herbert said <<Some code: Socket initializeNetwork "Only once per image" dst := Socket newUDP setPort: 1979. src := Socket newUDP setPort: 2345. buff := ByteArray new: 1026. delay := Delay forMilliseconds: 10. localhost := ByteArray withAll: { 192. 168. 42. 11 }. received := nil. rp := [[ received := dst receiveUDPDataInto: buff. received first isZero ] whileTrue: [ delay wait ]. WorldState addDeferredUIMessage: [ { buff. received } inspect ]] fork. src sendUDPData: ( 'ctmame' , (String value: 10) , (String value: 162)) toHost: localhost port: 1979. rp terminate. src closeAndDestroy. dst closeAndDestroy. src := nil. dst := nil. buff := nil. delay := nil. rp := nil. Smalltalk garbageCollect Socket allInstances>> That's great, thank you very much. I have a couple of other questions that sprang from using this code. 1. I couldn't get the WorldState addDeferredUIMessage: to do anything. What is supposed to happen? I am running the latest Pharo build. The class exists, and I didn't get a DNU, but I didn't get anything else either! 2. Out of curiosity, I tried used the NetNameResolver addressForName: method as a way of getting a socket address (instead of using the ByteArray. I tried this when nothing was working, and I noticed the method call in several of the Socket methods. However, Squeak gave me a DNU. Is there a simple way to enter host names using the NetNameResolver, or have I completely misunderstood its function? Cheers Andy

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chain reaction
by Christine Wolfe 06 Nov '09

06 Nov '09

I have an image morph X on top of which I have added two other morphs: A and B. I want to be able to click on morph A and have it move and at the end of its motion, automatically trigger the movement of morph B. Here's my dilemma. A, B, and X are all instances of different classes of morphs that I defined. X has two instance variables, a and b to which I assign new instances of the classes A and B. a responds to the mouse down event by moving - that part works. Now I want B to move too without the user having to do any more clicking. If I try to add a method to A that calls a movement method in B, it doesn't know what B is - I assume because at this point, I'm just defining the classes and they don't know about the instance names of other objects. I will greatly appreciate it if you can help me think of a way to make a chain reaction and a group of morphs based on clicking only one of the morphs. Thanks!

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Odd Transcript message
by Lynn Fogwell 03 Nov '09

03 Nov '09

Hi, Whenever I compile a particular method, the transcript displays the following line: IdentityManager class >> populateDevelopersTable (name is shadowed) So, it names the class and method I just compiled and then states that it is shadowed. What is 'shadowing' and how did I activate it for this particular method? PS) I am using the Pharo image, but they don't have a newbies list... Thanks, Lynn Fogwell

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Beginners November 2009