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WolfShade
WolfShade
Legend
Jan 17, 2019 5:44 PM UTC
Answered

Struct of functions [dispatch table]

Hello, all,

I am waiting for a customer to respond to a request, and thought I'd play around, for a bit, while waiting.  (Sometimes, these waits can go for days.)

I was thinking about something I had learned in Javascript a long time ago, and wondered if I could do the same thing in CF:  a dispatch table.

Here is an example of a JS dispatch table:

<a href="javascript:void(0);" alt="This is title one." id="title1" class="test">One</a>

<a href="javascript:void(0);" alt="This is title two." id="title2" class="test">One</a>

<a href="javascript:void(0);" alt="This is title three." id="title3" class="test">One</a>

<div id="testText"> </div>

<script> // Pretend I'm loading jQuery

    $(".test").click(function(){

        var divAlign = {

            title1:function(){$("#testText").css('textAlign','left');},

            title2:function(){$("#testText").css('textAlign','center');},

            dflt:function(){$("#testText").css('textAlign','right');}

            }

        var alignIt = function(doWhat){

            var doWhat = divAlign.hasOwnProperty(doWhat) ? doWhat : 'dflt' ;

            divAlign[doWhat]();

            };

        alignIt($(this).attr('id'));

        $("#testText").html($(this).attr('alt'));

        });</script>

Click a link, change the text in the div to the value of the alt attribute, and align the text based upon which one is clicked.  Slightly faster than a switch/case.

I'm trying to do the same in CFSCRIPT (but show alerts instead of changing the DOM), and I'm banging my head into a wall.  I have essentially the same code in CFSCRIPT, but I get an error:

"Element doWhat is undefined in divAlign"

I've even tried setting a variable called "doWhat" prior to creating the divAlign struct, and same error message.

What am I missing, here?

V/r,

^ _ ^

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    BKBK
    BKBKCorrect answer
    Community Expert
    Jan 19, 2019 10:28 AM UTC

    An idea:

    <cfscript> 

                obj = { 

                    title1:function(){writeOutput("<script>alert('Title One');</script>");}, 

                    title2:function(){writeOutput("<script>alert('Title Two');</script>");}, 

                    deflt:function(){writeOutput("<script>alert('Title Three');</script>");} 

                    }; 

                alertIt = function(doWhat){ 

                    var thisAction = "deflt"; 

                    if(StructKeyExists(obj,doWhat)){ 

                        thisAction = doWhat; 

                        } 

                    var func=obj[thisAction]; 

                    func();

                    }; 

                alertIt('title1');  

               alertIt('title2');   

               alertIt('abcd'); 

       </cfscript>

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    5 replies

    WolfShade
    WolfShadeAuthor
    Legend
    Jan 18, 2019 5:14 PM UTC

    Here is the code I have, so far, if it helps.  Error message is "Invalid CFML construct found on line 20 at column 37.  ColdFusion was looking at the following text: thisAction".

    <!DOCTYPE HTML>
    <html>
        <head>
            <meta charset="utf-8">
            <title>Untitled Document</title>
        </head>
        <body>
            <cfscript>
                obj = {
                    title1:function(){writeOutput("<script>alert('Title One');</script>");},
                    title2:function(){writeOutput("<script>alert('Title Two');</script>");},
                    deflt:function(){writeOutput("<script>alert('Title Three');</script>");}
                    };
                alertIt = function(doWhat){
                    var thisAction = "deflt";
                    if(StructKeyExists(obj,doWhat)){
                        thisAction = doWhat;
                        }
                    obj[thisAction]();
                    };
                alertIt('title1'); 
               alertIt('title2');  
              alertIt('abcd');
            </cfscript>
        </body>
    </html>

    V/r,

    ^ _ ^

    UPDATE:  I placed the code inside a try/catch block, and it's not triggering the catch.  It displays the same error message on the page, as if the catch were being ignored.

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    BKBK
    Community Expert
    BKBKCommunity ExpertCorrect answer
    Community Expert
    Jan 19, 2019 10:28 AM UTC

    An idea:

    <cfscript> 

                obj = { 

                    title1:function(){writeOutput("<script>alert('Title One');</script>");}, 

                    title2:function(){writeOutput("<script>alert('Title Two');</script>");}, 

                    deflt:function(){writeOutput("<script>alert('Title Three');</script>");} 

                    }; 

                alertIt = function(doWhat){ 

                    var thisAction = "deflt"; 

                    if(StructKeyExists(obj,doWhat)){ 

                        thisAction = doWhat; 

                        } 

                    var func=obj[thisAction]; 

                    func();

                    }; 

                alertIt('title1');  

               alertIt('title2');   

               alertIt('abcd'); 

       </cfscript>

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    WolfShade
    WolfShadeAuthor
    Legend
    Jan 22, 2019 1:50 PM UTC

    I'll give it a shot.  But I suspect that since the error message indicates that "thisAction" doesn't exist, it will still throw an error.

    I'll report back once I've tried it.  Thanks.

    V/r,

    ^ _ ^

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