ActionScript – Default Datatype for Untyped Variables?
if i don't specifically type a variable in my code will it compile as a default datatype? for example, the "for each ... in" function works best without typing the variable:
for each (var element in myArray)
{
//process each element
}
does my element variable have a datatype? if it is typed as Object is it better to actually write element:Object or does it matter?
EDIT
actually, that was a bad example, since the eleme开发者_StackOverflow中文版nt variable is going to be typed to whatever element is in myArray.
but is that how it works if a variable is untyped? it will simply become what is passed to it?
here's a better example for my question:
var a = "i'm a string"; //does this var becomes a String?
var b = 50.98; //does this var becomes a Number?
var c = 2; //does this var becomes an int?
for each (var element in myArray)
The element
variable doesn't have any data type - it is untyped and thus can hold anything.
And yeah, it is equivalent to writing element:Object
or element:*
, but it is always advisable to type your variables - this will help you catch some errors before you run the code. The mxmlc compiler will emit a warning if you don't do this, which can be fixed by typing it as e:Object
or e:*
.
var a = 45.3; //untyped variable `a`
a = "asd"; //can hold anything
/*
This is fine: currently variable `a` contains
a String object, which does have a `charAt` function.
*/
trace(a.charAt(1));
a = 23;
/*
Run time error: currently variable `a` contains
a Number, which doesn't have a `charAt` function.
If you had specified the type of variable `a` when
you declared it, this would have been
detected at the time of compilation itself.
*/
trace(a.charAt(1)); //run time error
var b:Number = 45.3;
b = "asd"; //compiler error
trace(a.charAt(1)); //compiler error
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