Learning ColdFusion 8: All Hail The New ++ Operator

ColdFusion 8 has introduced some new, very exciting mathematical operators. Most of these operators can be used through out the ColdFusion language while some (since ColdFusion is a tag-based language) can only be used and parsed properly from within a CFScript block. The following operators can be used any where: ++, --, %, +=, -=, *=, /=, %=, &&, ||, and !. The following operators can only be used within CFScript: ==, !=, <. <=, >, >=. And, &= can be used anywhere to concatenate a string to "self".

All of those operators are good, don't get me wrong, but I have been waiting so long for the ++ operator to get here. This operator increments a given value. Placing this operator before or after a variable has different effects. Placing it after the variable causes the variable to be evaluated first and then incremented. Placing it before the variable causes the variable to be incremented first and then evaluated.

This gives us the following output:

A. 0
B. 2

Notice that on line A, the value, intKisses, was evaluated and displayed prior to the increment. Then, on line B, it was incremented first and then evaluated and displayed. One of the first things that jumps to mind with this operator is how much nicer the last property of a FOR-Loop will look in CFScript:

This gives us the following output:

0,1,2,3,4

Notice how much nicer it was to use intI++ rather than the unsightly intI = (intI + 1). Does anyone else feel like shedding a tear or two over this simplistic beauty?

These operators can also be used inside of delated evaluation expressions, such as those used in conjunction with ColdFusion's IIF() method:

This gives us the output:

9
9

Notice that the operator acted on the variable, intKisses, only when the codition held true (and in a delayed manner). Also notice that not only was the value incremented for use in the display, the second outputted number proves that the value continues to be incremeted even after the delayed evaluation.

Another form of delayed evaluation is that of the tag-based ColdFusion condition method. Remember, the condition attribute of a condition loop is evaluated for each iteration of the loop to determine whether or not another iteration can take place. This is a place where these operators can be applied:

This gives us the output:

2 of 11
4 of 12
6 of 13
8 of 14
10 of 15
12 of 16
14 of 17
16 of 18
18 of 19
20 of 20

Not only was the variable, intHug, incremented explicitly in the body of the loop, the variable, intGoalHugs, was also evaluated for each iteration and at the time of that evaluation, the variable was incremted.

This operator also works in the Evaluate() method, but come on, does anyone still use that function??

The ++ operator will dynamically convert booleans into numeric values prior to evaluation:

This gives us the output:

2

In this case, since we are applying a mathematical operator, ColdFusion converts the boolean value of TRUE into a one. It then pre-increments the 1 and returns 2.

Similarly, using the ++ operator with date/time objects will dynamically convert dates into their numerical floating values and perform "date math" on them:

This gives us the output (this was run on May 31st):

01-Jun-07

One note of caution when using this operator to convert data types: since this operator acts directly on the variable, the ongoing data type of that variable is changed. So, for example, with out date math example, if, after we performed the date math, we output the intToday variable:

... we get the value:

39234.8717708

intToday no longer holds a date in string format.

There are, however, some limitations to the way these operators can be used. For starters, while they can be used as part of mathematical equations if the value being incremented is a variable:

... which gives us:

3

... if you tried to do that with a straight-up number:

ColdFusion will throw the following error:

Invalid CFML construct found on line 44 at column 3. ColdFusion was looking at the following text: ++

Now, why would you want to do that with a number, not a variable, no idea. You wouldn't, but at least now you know that it cannot be done.

These operators must not be used in conjuction with a nameless function return value. Imagine a scenario where we wanted to get the next available index of an array, we might do something like this:

Sounds good, but unfortunately, ColdFusion throws the same invalid CFML construct error. This is something that I could have seen being quite useful at times. It's a shame that ColdFusion doesn't handle returned values more elegantly in general (not just with operator use but with many commands really).

This operator cannot be used in conjunction with the access of an underlying Java method. Trying to pre-increment a number and then get its string value:

... throws the ColdFusion error:

Invalid CFML construct found on line 53 at column 22. ColdFusion was looking at the following text: (

Again, this is something that you probably will not do, but this is an exploration of the new ColdFusion 8 features. I am just trying to get a thurough sense of can and cannot be done.

While this is an in-depth exploration of ColdFusion 8's new ++ operator, I am sure most of the other new operators will have the same exactly or very similar limitations.

What Other People Are Searching For

[ local search ] coldfusion 8 tutorial
[ local search ] coldfusion 8 demo
[ local search ] coldfusion 8 samples
[ local search ] coldfusion 8 examples
[ local search ] learning coldfusion 8
[ local search ] coldfusion 8 operators
[ local search ] how to use coldfusion 8 operator

You Might Also Be Interested In: