I've been following with some interest the work of the CFML Advisory Committee on the CFML2009 specification, particularly the proposed enhancements to CFSCRIPT. The question of being able to call Custom Tags from CFSCRIPT has helped crystalize thoughts I've been forming for some time regarding the relationship between CFML tags and CFSCRIPT, and how to write better CFML applications.
The thing that makes CFML great is its tag-based syntax when used to generate dynamic HTML content. CFML is simply unmatched by any other web application development language in this regard. In fact, you could argue that JSP tag libraries (including the JSP Standard Tag Library) and ASP.NET server controls are nothing more than attempts to mimic CFML tag-based syntax.
However, CFML tag-based syntax is awkward and verbose when writing lengthy computational or business logic that isn't generating HTML output. CFML suffers in comparison to other programming languages in this regard. But, this is where CFSCRIPT shines. It's unfortunate that many (most?) people only know about CFML's tag-based syntax and are completely unaware of CFSCRIPT; and, that CFSCRIPT has often been treated as secondary to the tag-based syntax by both CFML developers and CFML server vendors. Conversely, while CFSCRIPT is good for computational or business logic, you would not want to use CFSCRIPT and the writeOutput() function to generate large amounts of HTML content.
In summary:
CFML tags. Good (great!) for generating dynamic HTML content. Bad for writing computational or business logic.
CFSCRIPT. Good for writing computational or business logic. Bad for generating dynamic HTML content.
If you accept this view, then the answer to the question of calling Custom Tags from CFSCRIPT is simple: don't do it. Custom Tags are an extension mechanism for CFML tag-based syntax. Custom Tags are intended to generate dynamic HTML content, not to contain computational or business logic. CFSCRIPT should be used for computational or business logic, not to generate HTML content. Calling Custom Tags from CFSCRIPT makes no sense.
Following on these thoughts, user-defined functions and components are extension mechanisms for adding computational or business logic to CFML, not for generating HTML content. In retrospect--and I'm not being critical here--the CFFUNCTION and CFCOMPONENT tags were probably a mistake. It might have been better for the CFML language and CFML developers if these features had originally been introduced and/or remained CFSCRIPT-only enhancements.
I welcome the proposed enhancements to CFSCRIPT, and have these suggestions for the CFML Advisory Committee and CFML developers:
- Don't add support for calling Custom Tags from CFSCRIPT to the CFML2009 specification. If it is added, CFML developers shouldn't use it.
- As soon as your favorite CFML server supports CFML2009 and the CFSCRIPT enhancements, ban the use of the CFFUNCTION and CFCOMPONENT tags. Require that user-defined functions and components be implemented using CFSCRIPT.
- Immediately ban the use of the writeOutput() function and require that all HTML content be generated using tag-base syntax.
Following these suggestions will take maximum advantage of the respective benefits of CFML tags and CFSCRIPT, and encourage separatation of presentation layer (CFML tags) and business layer (CFSCRIPT) logic within your applications. The result will be better organized CFML applications that are easier to enhance and maintain.
