Language Enhancements in ColdFusion Splendor – Elvis operator

April 8, 2014

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April 8, 2014

Language Enhancements in ColdFusion Splendor – Elvis operator

awdheshkumar Follow

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(12)

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The Elvis operator (?:) is a small but elegant feature added in Splendor. I am going to show you how it shortens your conditional code and makes it look simpler. But before I get into the details, here is the list of language features added in ColdFusion Splendor.

Script support for tags
Member functions for CF data type/data structure
Improved JSON serialization
Easy to use CF functions for Query tag
Elvis operator (?:)
Promoting built-in CF function to first class
Miscellaneous new functions: QueryGetRow, ListEach and others.

The Elvis operator assigns the ‘right default’ for a variable or an expression. In an expression, if the resultant value is not defined, then the object will be assigned to the left most part of the expression otherwise a default value (define at the right most part) will be assigned.

Consider a conditional case where the displayname is populated with username variable, if the later is defined otherwise a default value “anonymous” needs to be assigned to the displayname variable. The code snippet shown below display both the syntaxes: one with Elvis operator and other without it:

Without Elvis

<cfscript>
   if(isdefined('username')){
       displayName = username;
   }
   else {
    displayName = "anonymous";
   }
</cfscript>

With Elvis operator

   displayName = username ?: "anonymous";

The support for Elvis operator has been provided for function calls and expressions too. Some of the expression cases are:

 securityNumber = securityStruct[‘Joe’] ?: -1;  // Retrieving from a struct
 colourCode = colourArray[index] ?: "black";   // Retrieving from an array
 employeeName = getEmployeeName(ID) ?: “Joe”;  // A function call

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12 Comments

Anonymous

Apr 10, 2014

Anonymous

Apr 10, 2014

@Henry, that ?: example just shows how the Adobe guys don’t actually understand how the null coalescing operator is supposed to work, and have ballsed it up.

See: http://cfmlblog.adamcameron.me/2014/02/coldfusion-11-good-stuff.html#nullCoalescingOperator

—
Adam

()

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Anonymous

Apr 10, 2014

Anonymous

Apr 10, 2014

@James yes, but the use case is too similar.

However, I just checked out http://www.raymondcamden.com/index.cfm/2014/4/10/Recording-and-demos-from-my-ColdFusion-11-presentation and his sample demonstrates elvis operator much better.

displayName = encodeForHTML(url.name) ?: “Anonymous”;

Without the magic of the new elvis operator, it would have thrown undefined at the encodeForHTML call. It’s like adding a big hidden try/catch for the expression before the operator.

()

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Anonymous

Apr 10, 2014

Anonymous

Apr 10, 2014

I think it is a little different. The changes the username, whereas the Elvis operator does not

()

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Anonymous

Apr 8, 2014

Anonymous

Apr 8, 2014

Btw, is

displayName = username ?: “anonymous”;

the same as?

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Anonymous

Apr 8, 2014

Anonymous

Apr 8, 2014

Thanks Awdhesh. Can I make a (constructive) suggestion? Get your peeps to first post their code on http://codereview.stackexchange.com/, and tag it with “ColdFusion”. Then people like @Peter and myself and others will actually volunteer our time to help you with it.

I am more than happy to help you guys with this stuff. But the quid pro quo is you need to start realising that posting poor code like this in public actually does have a negative impact on the credibility of ColdFusion, and it also does not help your community as it perpetuates bad practice.

And it’d just be *so easy* to do the job right.

Cheers.

—
Adam

()

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awdheshkumar

Apr 8, 2014

awdheshkumar

Apr 8, 2014

@Adam: no, its not me. but your point is well taken.

()

Anonymous

Apr 8, 2014

Anonymous

Apr 8, 2014

This is part of the code shoddiness I mentioned above. There is no need to have the example usage as a single line of CFSCRIPT, which gives one the incorrect impression it’s a script-only thing.

It’s just an operator, so is tag/script agnostic. The example could have (and SHOULD HAVE) been:

—
Adam

()

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Anonymous

Apr 8, 2014

Anonymous

Apr 8, 2014

This new syntax has no tag use equivalence?

()

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Anonymous

Apr 8, 2014

Anonymous

Apr 8, 2014

@Awdhesh: are you the one writing the code for these blog articles / the docs that @Peter has draw your attn to recently?

If so – seriously – stop writing CFML. Get someone else to do it.

—
Adam

()

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awdheshkumar

Apr 8, 2014

awdheshkumar

Apr 8, 2014

@Peter, thanks for pointing this out. Will make sure this does not happen again.

()

Anonymous

Apr 8, 2014

Anonymous

Apr 8, 2014

Yeah, again I agree with @Peter: you guys need to actually a) write proper code; b) test it before you post it to the public. A lot of your readership will expect you to be competent at the language you are responsible for.

It is clear the person/people writing the code examples on this blog is incompetent with CFML. I am not exaggerating or being a meany, they’re just not up to the task of writing sample code which the CFML community is supposed to take-up.

Users of this operator should also be aware that you ballsed-up the implementation of it too: https://bugbase.adobe.com/index.cfm?event=bug&id=3710381

Someone there closed it with the excuse that it’s working “as designed”. This might be the case, but this just means the design is wrong.

But it’s a reasonable attempt at a nice addition to the language.

—
Adam

()

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Anonymous

Apr 8, 2014

Anonymous

Apr 8, 2014

You need to get a real CFML developer to proof-read these articles before you post them.

At the very least, attempting to run your own examples in CF would highlight the main issues.

()

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