Category: JavaScript

Public vs. Private Functions: When is it just redundancy?

A couple of years ago when I first delved into object-oriented programming I was reading a lot of different resources.  One spent a great deal of time describing “public” methods vs. “private” methods.  While I was a little confused at first, I quickly understood that “public” methods were ones that could be accessed from outside of the package (in my case, CFC), and that “private” methods weren’t visible to anything but other methods within the same package (and probably the NSA).  In other words…the actions that take place “behind closed doors”.

This same resource went on to emphasize that best practices dictate that your public methods should contain virtually none of your business logic. In fact, they recommended that your public methods be nothing more than pass-throughs that send the request information on to a similarly named private method.  For example, if your CFC has a method named “login” that is passed the username and password, the only thing that method will do is call a private method named “_login” (note the convention of prefacing private functions with an underscore), and pass it the username and password. Of course, if the private method returns a value the public method will capture the private method’s return value and echo it back to the original caller.

On the whole, this process makes sense to me and indeed is exactly how I have written my CFCs since.  But I am often finding that my CFCs seem to be twice as long as they should be. If I have four public methods, then I have at least four private methods.  And since I love to comment the heck out of everything, this can lead to long CFCs for fairly simple tasks.

So this has left me wondering what you as a developer do.  Is what I am doing “best practice” or is it just bloating my CFCs? Is there a better approach to this that offers the security of private methods without overloading the file with redundant comments and code? I would appreciate comments and suggestions.

As a side note, I have been wanting to employ this same model in the JS files I write. But I think I must be missing something. I can’t figure out how to make “private” methods in JS. Any insight on this would be great as well.

Still playing catch up….and still learning everyday….and loving every minute of it!

Dropping CFScript Functions into Your JS File

This post is about the cool similarities between Javascript and CF Script in ColdFusion.  But since this is my first post, a little introduction is in order.  I have been a web developer since 1996 and started with ColdFusion in 1998.  But once I got to ColdFusion MX, I got in a rut, lost my passion for programming and pretty much took a nap….a long nap….until about 2011. Boy did I miss a lot!!!  It was like waking up to a whole different world!

What an exciting time to be a developer!  With jQuery and a bazillion other JS libraries, MVC  frameworks, CFScript, mobile development, cool things like node.js  (I hear tell it actually flies little helicopters) and even databases without SQL (who knew that was possible), there is so much to learn!  I want to learn it all! But in the meantime, I hope to share some of what I find with you, both in my day to day work, and in memory dumps of things I have picked up since I awoke.  Feel  free to join me in the journey.

What better  way  to kick off  the Script Van Winkle  blog than with a discussion of script.  Before my nap I had programmed a ton in ColdFusion…but in all tags of course.  I had also programmed often in JavaScript, so that was familiar to me as well.  My first thought when hearing you could now do script in CF was,  of course, “why?”.  It did not make sense to me at first.

Despite being a disorganized mess in my private life, I love organization in my code.  I like it to look neat and easy to read.  I love white space and tabbing lines  to make code more readable.  In playing around with CF Script,  I found it looked more organized.  To me,  it seemed much more readable.   So I got it. I thought I had discovered why CF Script was cool.  It’s easier to read.  All the functions in my new or rewritten CFCs are now in script.

But it turns out there is so much more!  I was working on a project at my day job where, when building the page,  a call is made to a third party image renderer  for a preview image.  I have a function in my CFC (in script of course), that builds the URL to use to call the third party rendering.  It works great!

But we wanted to give the user the opportunity to make changes,  have that image rerender  based on those changes, and to do it without  necessarily having to use our server as a go-between.  So I had to write a JavaScript version of the CFC function that built the URL. This is where it got cool!

I copied the CF Script from that function into my JS file. Did it work right away? Of course not.  But it only took a few little adjustments to get it up and running. I did not have to rewrite the whole thing (and my comments didn’t need to change either).

You can do the same thing…just keep a few things in mind:

  1. Don’t forget, arrays in CF start at 1. In JS they start at 0.  This will likely trip you up at some point. Make sure you adjust any loops to reflect that. This usually entails starting loops at zero rather than one, and often your “less than or equal to” comparison to the length of the object you are iterating over, becomes simply “less than” the length.
  2. Speaking of decision operators, operators  such as  “is less than”, “lt”, “lte”, “gt”, “gte”, “is greater than”, “eq”, “equals”, etc.,  need to be changed to the JavaScript equivalents like “<“,  “<=”,  “>”,  “==”, “===”,  etc.  Make sure you have checked all of your loops for this as well.
  3. Speaking of loops, particularly those of the “for” variety, you can replace the incremental in CF with the JS equivalent. For example: “for (intX = 1; intX LT 3; intX = intX + 1)”, becomes “for (intX = 1; intX < 3; intX ++)”
  4. If you are using ArrayLen or ListLen, or just plain Len in CF, change those to use the “.length” function in JS.  For instance: “ArrayLen(aryItems)” becomes “aryItems.length”.
  5. Functions like “Replace” need to be switched out with JS version.  For example “Replace(strTestString, “saint”, “st.”) in CF becomes “strTestString.replace(“saint”,”st.”)  in JS.  There are a few CF functions that fall into this category.  Just figure that any function that takes a variable name as its first argument in CF probably has to modified.

While the amount of changes necessary will depend on the complexity of your particular function, you will more than likely find that a large percentage of the code is unchanged.  This is especially true if your DOM variables on the client side mirror your variables on the server side.  In my case,  I was dropping the entire object containing the graphics information to the DOM via JSON……but that is another post!

There are many reasons why you should switch to using CF Script, these are but two.  Happy scripting!!!!

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