ColdFused?

My Views on ColdFusion, Java and related technologies

Archive for February 15th, 2007

A page in CFSwitch-CFCase' diary

Feb 15

Posted by Rupesh Kumar in coldfusion | 1 Comment

Undoubtedly I am one of the most powerful programming construct of ColdFusion language. And definitely more powerful than all my cousins in other programming languages. All my cousins and even my brother (read java switch-case) work only on integers but I work on almost every kind of objects be it string or any numeric data or even date. Since I can work on almost all datatypes, I make cf developers life so much simpler. I was created this way because the world I was going to be in was UnTyped – where every one was equal and where there was no discrimination between datatypes and I really thank God (ColdFusion Architects) for creating such a wonderful world.
Recently I heard someone talking about me that I am not as fast as my cousins. Some one even talked about ignoring me and taking help of kiddo cfif-cfelse. I dont want to say anything against anyone coz I know “with great power comes great responsibility err..cost”.

Its sheer hardwork that makes me so much more powerful than all my cousins. This is what I do when any object comes to me. First I try to see if it is numeric. I do that because that is what all my cousins are used to and I have to remain as fast as them in that case. If it is not numeric, then I check if it can be date. If it is not even date, I try converting it in String. Once I arrive at the data, I use my own data structure to match it with appropriate CASE. So when the data is string, i will take some more time as compared to what i will take when data is numeric. Is that so bad? My cousins dont even do that!

Sometimes I compare myself to a busy lawyer who likes working on many CASEs. I dont like to work just for 2-3 cases. I prefer my grandson cfif-cfelse take care of those small no of cases.
I hope someday people will read these pages and if even after reading this they think that I am too slow and I should be ignored I only want to say “God, forgive them, for they dont know what they are doing!”.

Performance Tips : ColdFusion List

Feb 15

Posted by Rupesh Kumar in coldfusion, performance | 3 Comments

how many of you have written/seen code like this?

<cfset mylist="jan,feb,mar,apr,may,jun,jul,sep,oct,nov,dec">
<cfloop from="1" to=#ListLen(mylist)# index="i">
 <cfset month = ListGetAt(mylist, i)>
 <!--- do something with this month --->
 <cfoutput>#month#</cfoutput>
</cfloop>

While there is nothing wrong with it syntactically or functionally, performance wise it is very poor. Why? ColdFusion list is nothing but String (delimited by delimiter). ColdFusion does not have any way to build any intelligence to keep it in any other datastructure because you can use it like a normal string also. So what happens when you call any List function on this string? We parse the string using the delimiter and get the delimited tokens and process that.
Now lets take ListGetAt(list, index) function. It will keep parsing and getting the token unless it reaches the required index. Imagine doing in a loop. We will be parsing the same string again and again and traversing from the beginning everytime till we reach the next loop index. So, in the Nth iteration, it will start from beginning and tokenize N times. Thus by the time you have completed the loop, you have parsed/tokenized the string N*(N+1)/2 times. Isn’t that too costly? Lesson – Never ever use ListGetAt() in a loop. Either iterate using OR convert the list into array using ListToArray() and iterate over it. Using cfloop is the most optimized way to do this.

Even if you are not iterating over list but you need to call ListGetAt() many times, it is better to convert it to array and then search the index in that.

Same thing applies to search functions like ListFind, ListContains etc. If you need to call these multiple times on the same list, you will be better off converting the list to array and searching in that.

If you need to append many items to the list, then also you will get a better performance by converting the list to array and doing all appends on that.

This does not mean you should not use list at all or you should always convert the list to array and work on that. If the number of operations that you are doing on the list is less, you should stick to list because converting the list to array is also costly. If you are inserting an element in the middle of list, list will be better than array in most cases.