Multiple identifiers

BlitzMax Forums/BlitzMax Programming/Multiple identifiers

Marmoth

(Posted 2009) [#1]

Hello,

There is one thing about BMax that still confuses me: how to make more than one identifier pointing on the same variable so that i can modify this single variable using any of them?

The rough idea:
-------
a=1

b=a

b=b+1

print a
------

and have the printed text be "2".

Don't hesitate to ask if i didn't make me clear.

Thanks in advance for your answers!

BladeRunner

(Posted 2009) [#2]

For simple basic types as Int, float, double, you can't do this.
What is possible is to use var in function headers:

bar = 1
foo(bar)
print bar
function foo(bar:int var)
    bar:+1
end function

Objects always are treated as references, so

type foo
    field bar:int
end type

a:foo = new foo
a.bar = 1
b:foo = a
b.bar:+1
print a.bar

will behave like you want it to.

ImaginaryHuman

(Posted 2009) [#3]

You can do it with pointers.

local a:Int=1
local b:Int Ptr=VarPtr(a)
b[0]:+1
print a

Marmoth

(Posted 2009) [#4]

Thank you very much for your quick and useful answers!

:-)

NB: Pointers don't work with custom types. For object, only fields seems to work this way (if you nullify the second object variable, the first will still be there).