Installation guide

Specifying file attributes as relative URI paths improves the portability of CFML pages

by eliminating web server and operating system specific physical path specifications.

Note in the above example that the first tag is not portable to a Linux running Apache,

but the second one is.

The optional

URIDirectory attribute accepts the values “Yes” and “No”; the default

value is “No”.

4.5 New CFML Tags

This section lists new CFML tags that are unique to BlueDragon.

4.5.1 CFASSERT

CFASSERT is a new CFML tag introduced by BlueDragon that can be used as a testing

tool to enhance the reliability and robustness of your applications. The concept of using

assertions is frequently found in more advanced languages, and it’s critical to effective

unit-testing of your applications. Complete discussion of the benefits and uses of asser-

tions is beyond the scope of this manual, but a brief explanation follows.

CFASSERT (and its corresponding assert() function discussed in Section 5.4.1) takes an

expression that is expected to evaluate to a Boolean result (true or false). It throws an

exception if the result is false but does nothing if the result is true. They are also ignored

if assertions have not been enabled in the BlueDragon admin console, as discussed at the

end of this section. The intention is that you can place these assertions in your code to

help ensure that some expected state of the application is indeed occurring as expected.

More accurately, they cause failure if the state is not as expected.

A typical use is during testing, when you expect that a given variable will have a given

value (or perhaps a range of values), perhaps after calling a custom tag, UDF, or CFC

method. Another example is when you want to test the mere existence of a given variable

(such as an expected session or application variable).

The difference between this and using a

CFIF is that the CFIF is intended to control the

flow of the logic, executing code depending on a condition. An assertion test is intended

to simply throw an error is the expected condition is not true. The

CFIF test handles

expected conditions, while the assertion flags unexpected conditions.

It could be surrounded by a

CFTRY to catch and handle the error that will be thrown, or

the error can be allowed to pass up to the caller of the code throwing the exception. It

could also be left to be handled by any

CFERROR or site-wide error handler, or if unhan-

dled will simply result in a BlueDragon runtime error. (There is a body of opinion in the

industry that suggests that assertion failures should not be caught at runtime, or at least

ought not be used to alter the flow of processing and allow execution to continue. These

proponents expect that an assertion failure should result in a cease of processing.)

BlueDragon 6.1 CFML Compatibility and Reference Guide 23