The problem with not testing my code:
Enginestart
start the engine
[self fuel notEmpty] whileTrue: [
movement := self fuel burnFuelWith: self spark
].
self transmission addMovement: movement
Doesn't move until the gas runs out! :)
So how about:
Enginestart
start the engine
self spark turnOnElectricity.
self engageStarter.
self car isKeyInOnPosition whileTrue: [
self runEngine
].
EnginerunEngine
run engine and pass movement to car
self fuel notEmpty ifTrue: [
movement := self fuel burnFuelWith: self spark
self transmission addMovement: movement
] ifFalse: [
self flashAnnoyingGasGuageLight.
].
Ok I realize I'm probably only amusing myself but just incase it helps
someone I thought I'd point out my mistake!
Happy coding!
Ron
From: Ron Teitelbaum
Sent: Tuesday, June 06, 2006 9:43 AM
Hi Marko,
How are things in Finland? I hear it is nice there and there seems to be
a
bit of a marketing campaign to get Americans to visit.
Anyway let's get to your question. There are a number of ways to pass
variables around. The least effective way is to call methods with a lot
of
parameters. Usually when I see methods with lots of parameters there is a
problem and the problem most likely is that the methods is implemented in
the wrong class.
Consider for a moment an example (since you asked for code examples)
Object subclass: Car
Object subclass: Engine
Object subclass: Fuel
Object subclass: Spark
Now we all know that for engine it run it needs Fuel and Spark so we could
model the car so that it has each
Car
instanceVariables: 'engine fuel spark'
Then we have
Carstart
Start the car
self engine startWithFuel: self fuel andSpark: self spark onCar:
self
EnginestartWithFuel: someFuel andSpark: someElectricity onCar: aCar
run the engine
[someFuel notEmpty] whileTrue: [
movement := someFuel burnFuelWith: someElectricity
].
aCar addMovement: movement
CaraddMovement: someMovement
handle the movement of the engine through a transmission
self transmission handleMovement: someMovement
Ok so now I'm just amusing myself and thinking of the car being in idle so
not using the fuel to move at all, wasting gas and promoting global
warming.
Getting back to your question what would happen instead if we have the
parameters modeled where they are needed. Ask yourself does the car need
gas and fuel or does the engine need it instead?
So
Car
instanceVariables: 'engine'
Engine
instanceVariables: 'fuel spark transmission car'
Now when we build the objects we get much less parameter passing.
Carstart
start the car
self engine start
Enginestart
start the engine
[self fuel notEmpty] whileTrue: [
movement := self fuel burnFuelWith: self spark
].
self transmission addMovement: movement
Now this was a long answer to your question and you may be sitting there
saying; What does this have to do with databases and buttons!
Well if you model your parameters in objects they don't need passing.
TestDatabase
instanceVariables: 'dataSource user password myDBConnection'
Then your button's method #executeTest
TestDatabaseexecuteTest
self myDBConnection on: self dataSource logon: self user password:
self password.
Where dataSource can have host and port and dbname ...
I hope this helps for specific examples you could try
http://www.google.com/search?hl=enq=mysql+squeak
If this doesn't make sense, feel free to ask questions. Let me know how
it
goes!
Happy coding!
Ron Teitelbaum
President / Principal Software Engineer
US Medical Record Specialists
[EMAIL PROTECTED]
From: Marko Koivuniemi
Sent: Monday, June 05, 2006 4:14 PM
Greetings from Finland. I am very excited about Squeak and SmallTalk - I
have find myself trying and exploring new programming things and that
hasn't happen since days of Commodore 64.
Now I am trying to build (with one partner) a program which uses MySQL.
I wonder what would be best way to do login screen and actual program.
Now we have morphs in windows which has login and password fields and
button. At this time idea is that this startup screen test login
information and then sends user (or user id) to another screen.
I tested various styles and this kind of test works with button.
test := DatabaseTest new.
loginbutton := MyButtonMorph new send: #executeTest to: test;
openInHand.
But what would be the best way to send many variables or values with
button click. (I have couple TextFieldMorphs storing values)
I have googled a lot - and most examples deals scriptable buttons. (And
that is something I am not familiar
