The Secret Powers of Includes

1
The Secret Powers of Includes
More than just pulling in code

• Charlie Arehart, CTO, New Atlantacharlie_at_newatlan
  ta.com

2
Overview

• Some common challenges
• Typical use of CFINCLUDE
• CFINCLUDE as code include
• Suprising Uses of CFINCLUDE
• CFINCLUDE as output grabber
• CFINCLUDE as content sender
• CFINCLUDE as file reader
• Processing application.cfm on include
• The many ways to reuse CFML code
• Presentation is based on article from July 2003
  CFDJ article of the same name
• http//www.sys-con.com/coldfusion/article.cfm?id6
  27
• Area provided at bottom of page for comments,
  feedback
• Or send me email directly charlie_at_newatlanta.com

3
Audience

• Whether experienced or newcomer to CFML, youll
  likely learn something new
• Some aspects apply to CFMX/BlueDragon
• Others apply to CF4 and 5 as well
• Some are new in BlueDragon only
• Most will apply and be useful to all CFML
  developers

4
About Your Speaker

• CTO of New Atlanta Communications since April 03
• Company based in Alpharetta, GA (30 miles north
  of Atlanta)
• 7 yrs CF experience (21 yrs in Enterprise IT)
• Co-author, ColdFusion MX Bible (Wiley)
• Frequent contributor to ColdFusion Dev Journal
• Past accomplishments of note
• Tech Editor, CFDJ
• Allaire/Macromedia Certified Adv CF Developer (4,
  5, MX)
• Allaire/Macromedia Certified Instructor
• Team Macromedia Member Customer Advisory Board
  Member
• Contributor to Macromedia Devnet, Dev Exchange
• Frequent speaker to user groups, conferences
  worldwide
• Also pursuing Masters at Dallas Theological
  Seminary
• part-time via Atlanta extension campus

5
Some Common Challenges

• Can you include a file other than CFML?
• Have you ever needed to send a file to a user
  when CFCONTENT is disabled?
• Have you ever needed to read a file if CFFILE is
  disabled?
• Have you ever wished that including a file would
  also execute its application.cfm at the same time?

6
What is CFINCLUDE?

• What does CFINCLUDE do, really?
• Is it a compile-time directive to pull code
  from one file into another?
• I will argue that no, its not
• Ill show you how and why
• What does that mean? How is it useful?
• Lets look at the many ways CFINCLUDE can be used

7
CFINCLUDE as Code Include

• We all know of using CFINCLUDE to include headers
  and footers on a page
• Typically done on many pages
• Benefit changes to the header/footer are
  immediately available to all including pages
• And we also know about the shared variable scopes
• Variables created/changed in included file are
  available to calling page, and vice-versa
• Challenge this can lead to unexpected results

8
Pulling Code? At Compile Time?

• But is it really pulling in code?
• Other languages do includes, like Cs include
• These pull in code at compile time
• Is that what CFML does? No.
• Need proof?
• CFINCLUDEs TEMPLATE attribute can be a variable.
  Really!
• Code can be changed in included file without
  recompile of including page
• CFMX allows you to see the date of compiled
  classes
• Change included file and run caller caller is
  not recompiled
• You cant open a tag in caller and close it in
  include

9
CFINCLUDE as Output Grabber

• So whats really happening?
• CFINCLUDE seems almost like a custom tag
• Simply gets output of included file, but with
  shared scope
• This is hard for experienced CFers to accept, but
  mull on it
• As further demonstration, the code included
  does not need to be a CFML file
• Could you CFINCLUDE an XML file? Yes!
• What does it do? Just shows it on screen
• But you may want to render it with proper mime
  type, and turn off debugging
• ltcfsetting showdebugoutput"No"gt
• ltcfcontent type"text/plain"gt
• ltcfinclude template"test.xml"gt
• Could certainly use CFSAVECONTENT to catch that
  output and process later in the template

10
CFINCLUDE as Content Sender

• If you can send XML, can you send a PDF?
• Sure, prefacing it with ltCFCONTENT
  TYPE"application/pdf"gt
• Couldnt you just use CFCONTENTs file attribute
  instead? What are differences?
• CFCONTENT allows full path, CFINCLUDE allows only
  relative path (or use of mapping)
• CFCONTENT FILE stops page processing
• CFCONTENT may be disabled for security reasons
• Interesting security concern CFINCLUDE cant be
  disabled

11
CFINCLUDE as File Reader

• Similarly, you may know that CFFILE allows
  reading of a files contents into a variable
• But what if its disabled for security reasons?
• CFINCLUDE can come to the rescue
• We saw CFINCLUDE can grab output of any file,
  including a text file
• Recall that CFSAVECONTENT can be used to capture
  that?
• ltCFSAVECONTENT VARIABLE"input"gt
• ltCFINCLUDE TEMPLATE"test.txt"gt
• lt/CFSAVECONTENTgt
• ltCFOUTPUTgtinputlt/CFOUTPUTgt
• Again, could circumvent security, for better or
  worse
• Now can you see why I titled the presentation as
  I did?

12
Processing Application.cfm on Include

• Finally, have you ever wished you could include
  a file, or call it as a custom tag, and have it
  execute its application.cfm (and
  onrequestend.cfm)?
• Not something youd always want, but could make
  sense
• Some force-fit using CFHTTP to enable this
• Can CFINCLUDE do this?
• No, not in CF (but BlueDragon does offer such an
  option)
• Thought it is possible in CFMX if you know the
  right trick

13
GetPagteContext().include()

• You can make this happen with MXs new
  getpagecontext().include()
• Also supported in BlueDragon 6.1
• Despite what MX docs say, this is for more than
  including JSPs
• Can call CFM pages as well
• And it DOES execute the page along with its
  application.cfm and onrequestend.cfm!
• Also be aware of getpagecontext().forward() for
  doing forwards
• See my June 2002 CFDJ article on forwards, or
  server-side redirects
• http//www.sys-con.com/coldfusion/article.cfm?id4
  50

14
BlueDragons CFINCLUDE PAGE

• BlueDragon supports getpagecontext().include()
• And also getpagecontext().forward()
• And it also adds CFINCLUDE PAGE attribute to do
  these enhanced includes
• Does same as getpagecontext().include()
• Can include JSPs/servlets in Java editions,
  ASP.NET pages in .NET
• Also executes the application.cfm/onrequestend.cfm
  in CFML pages
• Also adds CFFORWARD to make forwarding easier
• Does same as getpagecontext().forward()
• Both these can open new doors to true MVC design
• But be aware with both page processing stops on
  caller
• And with forward, output of caller is flushed
  first

15
Bonus topic Trusted Cache and Included Content

• Background trusted cache setting in Admin
• Both CF and BlueDragon support this feature
• Intended to prevent server looking to find
  changed source code in templates, once template
  is executed and cached
• At least until server is restarted (or cache is
  flushed)
• Performance benefit less file I/O
• Typically used in production environment
• But what happens with included content when you
  enable trusted cache?
• Both CF and BlueDragon wont detect changes in
  included files
• Nor in application.cfm nor onrequestend.cfm
• To cause them to see changes in CFMX
• turn off trusted cache
• execute the page to cause it to be updated, then
  turn cache back on
• In BD, can use flush cache button in admin File
  CachegtRuntime State

16
The Many Ways to Reuse CFML Code

• So, how many ways can you reuse code in CFML now?
• From CF 4 and 5 (and BlueDragon 3)
• CFINCLUDE
• Custom tags and CFMODULE
• Application.cfm and OnRequestEnd.cfm
• CFLOCATION
• CFSCRIPT-based UDFs
• From CFMX and BlueDragon 6.1
• getpagecontext.include() and getpagecontext.forwar
  d()
• CFCs
• CFFUNCTION
• BlueDragon 3 and 6.1 add
• CFINCLUDE PAGE and CFFORWARD

17
Summary

• Learned that CFINCLUDE has powers you may not
  have expected
• Its NOT about pulling in code
• More about pulling in another pages results
• Can include other than CFML
• Can use as alternative to CFCONTENT, CFFILE
• Other approaches also exist to reuse code
• Some offer features well beyond CFINCLUDE
• Can even trigger application.cfm to execute
• All together, they offer many options to expand
  your CFML development

18
Contact info

• Charlie Arehart, CTO, New Atlanta
• Charlie_at_newatlanta.com
• [phone]

19
(No Transcript)
20
(No Transcript)