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Mr. T

Sun Jun 04, 2006 2:27 pm


Exporting Variables from Procedures

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procedure test (var a : int)
    a := 3
end test

put a

Clearly this won't work because the variable 'a' only exists in its own little procedure world.  But let's say there's an instance when i need to export a variable (along with its value) from a procedure.  How would I go about doing this?


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wtd

Sun Jun 04, 2006 2:39 pm



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Ok, so you have...

procedure test (var a : int)
    a := 3
end test

Now, let's declare a variable.

var foo : int := 42

Now, let's pass it to the procedure.

test (foo)

Now, let's see what the value of "foo" is.

put foo


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Mr. T

Sun Jun 04, 2006 2:45 pm


Alex's Opinion

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Ok, but doesn't doing that render a := 3 inside the procedure useless?


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Cervantes

Sun Jun 04, 2006 3:25 pm



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No, it is not useless. It will change the value of the variable you pass to it (foo, in this case).

However, this is a terrible practice. Parameters are good, but when the procedure is allowed to change the value of the variables you pass in as parameters, you've got a situation almost as bad as global variables.

If you want to change the value of 'foo', don't do it from within the procedure. Rather, make your procedure a function and use that.


function test : int
    result 3
end test
var foo : int := 42
put foo
foo := test
put foo


42
3



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Mr. T

Sun Jun 04, 2006 3:36 pm


Alex's Opinion

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Thanks.  :P