Default parameters in ActionScript 3.0 - actionscript-3

I have a function, for example
function test(p1:int=7,p2:Boolean=true,p3:uint=0xffff00,p4:Number=55.5)
{
//instructions
}
How to change only p4, for example, and parameters p1,p3,p3 was still default?
Next time I want to change for example only p2, and parameters p1,p3,p4 was still default?
etc.

you could always do something like (but I don't think it's a great idea):
private function test(a1:Object=null, a2:Object=null, a3:Object = null, a4:Object = null):void {
var p1:int = (a1 !== null ? int(a1) : 3);
var p2:Boolean = (a2 !== null ? Boolean(a2) : true);
var p3:uint = (a3 !== null ? uint(a3) : 0xFFFF00);
var p4:Number = (a4 !== null ? Number(a4) : 55.5);
}
that way if you want something to be default, you can just pass in null:
with:
test(null,false,null,null);
but again, it's a bad idea. Maybe make the parameter an object -- it sounds like you're passing in a colortransform object -- which already has rgb + alpha + transparency? (just a wild guess)

You can't. You can leave p3 and p4 out and they will use the default value when you want to only specify p2. But then you'd have to enter a value for p1 too.

Related

Is there a simple way to have a local webpage display a variable passed in the URL?

I am experimenting with a Firefox extension that will load an arbitrary URL (only via HTTP or HTTPS) when certain conditions are met.
With certain conditions, I just want to display a message instead of requesting a URL from the internet.
I was thinking about simply hosting a local webpage that would display the message. The catch is that the message needs to include a variable.
Is there a simple way to craft a local web page so that it can display a variable passed to it in the URL? I would prefer to just use HTML and CSS, but adding a little inline javascript would be okay if absolutely needed.
As a simple example, when the extension calls something like:
folder/messageoutput.html?t=Text%20to%20display
I would like to see:
Message: Text to display
shown in the browser's viewport.
You can use the "search" property of the Location object to extract the variables from the end of your URL:
var a = window.location.search;
In your example, a will equal "?t=Text%20to%20display".
Next, you will want to strip the leading question mark from the beginning of the string. The if statement is just in case the browser doesn't include it in the search property:
var s = a.substr(0, 1);
if(s == "?"){s = substr(1);}
Just in case you get a URL with more than one variable, you may want to split the query string at ampersands to produce an array of name-value pair strings:
var R = s.split("&");
Next, split the name-value pair strings at the equal sign to separate the name from the value. Store the name as the key to an array, and the value as the array value corresponding to the key:
var L = R.length;
var NVP = new Array();
var temp = new Array();
for(var i = 0; i < L; i++){
temp = R[i].split("=");
NVP[temp[0]] = temp[1];
}
Almost done. Get the value with the name "t":
var t = NVP['t'];
Last, insert the variable text into the document. A simple example (that will need to be tweaked to match your document structure) is:
var containingDiv = document.getElementById("divToShowMessage");
var tn = document.createTextNode(t);
containingDiv.appendChild(tn);
getArg('t');
function getArg(param) {
var vars = {};
window.location.href.replace( location.hash, '' ).replace(
/[?&]+([^=&]+)=?([^&]*)?/gi, // regexp
function( m, key, value ) { // callback
vars[key] = value !== undefined ? value : '';
}
);
if ( param ) {
return vars[param] ? vars[param] : null;
}
return vars;
}

Need to alter space from postal code in results array

Hi my requirement need to get postal code from
var address= results[0].formatted_address ;
this formatted value.
Because nether land address have "Danzigerkade 12,1013 AP Amsterdam,Netherlands" this kind of address. but i don't want postal code like this"1013 AP" . i need "1013AP" like this.
Please give me the solution.
Thanks in advance.
I don't recommend parsing the formatted_address to get the postal code or any other specific address fields. Instead, you should scan through the address_components and check the types array of each one to find the address field you need. This is much more reliable than parsing the formatted string.
Once you have the postal code, removing the space is trivial.
To find the postal code for an entry in your results array (e.g. results[0]), you can use code like this:
function getAddressComponent( result, type ) {
var components = result.address_components;
for( var i = 0; i < components.length; ++i ) {
var component = components[i], types = component.types;
for( var k = 0; k < types.length; ++k ) {
if( types[k] == type ){
return component;
}
}
}
return {};
}
var component = getAddressComponent( results[0], 'postal_code' );
var postalCode = component ? component.short_name : '';
var postalCodeNoSpace = postalCode.replace( ' ', '' );
console.log( postalCodeNoSpace );
Update in reply to your comment:
The code you're asking about with ? and : uses the conditional operator found in JavaScript and many other languages:
var postalCode = component ? component.short_name : '';
That works just like this longer form that should look more familiar:
if( component )
postalCode = component.short_name;
else
postalCode = '';
The idea was to not try to reference component.short_name if component itself is null or undefined, because of course that would be an error. In other words, to protect the program from crashing if getAddressComponent() does not find a postal code.
But interestingly enough, there's a bug in the way I was using it. Look at the last line of getAddressComponent():
return {};
Originally I was going to return null there - and then the code you asked about would have been correct - but for some reason I decided to return an empty object instead. So the code in question wasn't quite right with that change.
One way to fix this would be to go back to what I originally meant to do, and change the last line of getAddressComponent() from this:
return {};
to:
return null;

which method should i use to create a new keyboard using adobe flash

I'm trying to create a new keyboard somehow, for educational purposes.
I've written this code using actionscript 3.I've created an input text field (named it t1) .when the user presses q button on keyboard(which has an ASCII aquals 81 ) I want the letter b to be printed out on the text field so i've written this code :
stage.addEventListener(KeyboardEvent.KEY_DOWN, pressing);
function pressing(event:KeyboardEvent):void
{
//trace(event.keyCode);
if(event.keyCode==81)
t1.replaceSelectedText("b");
}
the problem was that the method replaceSelectedText prints the tow letters on the screen(q&b) which method can i use instead?
Any help would be appreciated.
When using the replaceSelectedText method, you first need to select the text you want to replace. This can be done with the "setSelection" method. This from the adobe help website:
setSelection(beginIndex:int, endIndex:int):void
"Sets as selected the text designated by the index values of the first and last characters, which are specified with the beginIndex and endIndex parameters."
At the moment, since you don't have any text selected, it appears to just be adding the text "b" as it's replacing nothing. Therefore, you should try first selecting the "q".
Alternatively, you can just use a different method. from the adobe help website:
replaceText(beginIndex:int, endIndex:int, newText:String):void
"Replaces the range of characters that the beginIndex and endIndex parameters specify with the contents of the newText parameter."
This would cut out an extra line of code.
I haven't actually done this myself, so if that doesn't work, here's the link to the adobe help page for Text Fields: http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/text/TextField.html
I think that to do what you are looking for ( replace a char when it's typed ), a KeyboardEvent.KEY_DOWN is not enough, because when that event is fired, the text is not yet changed, so any change that you did in its handler to your text field will not cancel the insertion of the current typed char. Also, using KeyboardEvent.KEY_UP ( in addition to KeyboardEvent.KEY_DOWN ) will not resolve the problem, because you can fire n times a KeyboardEvent.KEY_DOWN event with the KeyboardEvent.KEY_UP event fired once !
So, I think that the best event that can do the job is the Event.CHANGE event which is fired every time the text of your text field is changed, so you can do like this :
// is there a char to replace ?
var replace_char:Boolean = false;
// the position of the char that we want to replace
var char_position:int = -1;
var text_input:TextField = new TextField();
text_input.type = 'input';
text_input.border = true;
text_input.addEventListener(Event.CHANGE, onTextChange);
function onTextChange(e:Event):void {
if(replace_char && char_position >= 0){
text_input.replaceText(char_position, char_position + 1, 'b');
replace_char = false;
}
}
addChild(text_input);
stage.addEventListener(KeyboardEvent.KEY_DOWN, _onKeyDown);
function _onKeyDown(e:KeyboardEvent):void {
if(e.keyCode == 81) {
replace_char = true;
char_position = text_input.selectionBeginIndex;
}
}
EDIT :
To use a list of keys and their equivalents, you can use an object to stock your keys like this :
// list of all keys (chars) and their equivalents
var chars:Object = {
81: 'b', // q => b
83: 'v', // s => v
68: 'c' // d => c
// other chars
}
var char_to_replace:int = -1;
// other instructions
function onTextChange(e:Event):void {
if(replace_char && char_position >= 0 && char_to_replace >= 0){
// get the equivalent of the pressed key from chars object using : chars[key_pressed]
text_input.replaceText(char_position, char_position + 1, chars[char_to_replace]);
replace_char = false;
}
}
// other instructions
function _onKeyDown(e:KeyboardEvent):void {
if(chars[e.keyCode]) {
replace_char = true;
// save the last pressed key to get its equivalent, or save this last one directly, to replace it next
char_to_replace = e.keyCode;
char_position = text_input.selectionBeginIndex;
}
}
Hope that can help.

Coding a triple-state Boolean in AS3

I know that a Boolean can have only 2 values, false and true. And I can code a Class that has a property that can have 3 states. But how can I code it in such a way so that, when setting or getting its state, I can refer to the object itself as opposed its property? eg:
var triBoolean:TriBoolean = 0;
// later...
triBoolean = 1;
The reason I want to do this is so I can have a value that toggles through three states and I'm assuming it would be quicker to refer directly to the object - but perhaps that's not right.
Or is it only primitive types that can be used in this way?
If you use an Object type you can do it, having: (null, true or false) tri-state, you will lose type safety, but still valid:
var triBoolean:Object = null;
// Then you can assign your triple states...
triBoolean = false; //valid
triBoolean = true; //valid
triBoolean = null; //valid

What does this line of Actionscript do?

I'm looking at the as3delaunay library and most of the code is clear to me. This part is not, however (note the line that I put preceded with an arrow):
public function circles():Vector.<Circle>
{
var circles:Vector.<Circle> = new Vector.<Circle>();
for each (var site:Site in _sites)
{
var radius:Number = 0;
var nearestEdge:Edge = site.nearestEdge();
=======>> !nearestEdge.isPartOfConvexHull() && (radius = nearestEdge.sitesDistance() * 0.5);
circles.push(new Circle(site.x, site.y, radius));
}
return circles;
}
For reference, isPartOfConvexHull() is found in Edge.as and looks like this:
internal function isPartOfConvexHull():Boolean
{
return (_leftVertex == null || _rightVertex == null);
}
What does !nearestEdge.isPartOfConvexHull() do? Does that mean that the radius = nearestEdge.sitesDistance() * 0.5 only executes if false is returned from the call to isPartOfConvexHull()? Does that stop execution of any other code?
It is equivalent to:
if (!nearestEdge.isPartOfConvexHull()) {
radius = nearestEdge.sitesDistance() * 0.5;
}
In the following line:
var b:Boolean = expression1 && expression2;
expression2 will not be evaluated if expression1 is false because we already know the final result: b = false.
Now in the following line:
expression1 && expression2;
The same thing happens except the fact that we are not assigning the result to a variable.
And this is exactly what happens in the line you are asking about where !nearestEdge.isPartOfConvexHull() is the first expression and (radius = nearestEdge.sitesDistance() * 0.5) is the second expression.
To extends #sch answer with some explanations (I didn't knew if editing answer to almost double it was ok).
This is based on lazy execution of the interpreter. If (!nearestEdge.isPartOfConvexHull()) is False then there's no need to execute the second part of the AND statement to know it'll be False, then it's left unexecuted. If it's true the evaluation of the complete statement is needed (and then done) to tell wether or not this boolean is True. So this is equivalent to an if statement.
TMHO this is bad code since it's to much condensed and hard to understand.