Selecting how to create variable names
The
following two examples describe cases when you need dynamic variable names:
Form applications where the number and names of fields
on the form vary dynamically. In this case, the form posts only
the names and values of its fields to the action page. The action
page does not know all the names of the fields, although it does
know how the field names (that is, the variable names) are constructed.
If the following are true:
ColdFusion calls
a custom tag multiple times.
The custom tag result must be returned to different variables
each time.
The calling code can specify the variable in which to return
the custom tag result.
In this case, the custom
tag does not know the return variable name in advance, and gets
it as an attribute value.
In both cases, it might appear that dynamic expressions using
the Evaluate function are needed
to construct the variable names. However, you can achieve the same
ends more efficiently by using dynamic variable naming, as shown
in Example: a dynamic shopping cart.
This does not mean that you must always avoid dynamic evaluation.
However, given the substantial performance costs of dynamic evaluation,
first ensure that one of the following techniques cannot serve your
purpose:
An array (using index variables)
Associative array references containing expressions to access
structure elements
Dynamically generated variable names
