Comments on: isDefined() vs structKeyExists() http://www.simonwhatley.co.uk/isdefined-vs-structkeyexists The opposite of every great idea is another great idea Fri, 21 Nov 2008 22:14:51 +0000 http://wordpress.org/?v=2.6.3 By: Paul Thornton http://www.simonwhatley.co.uk/isdefined-vs-structkeyexists#comment-2945 Paul Thornton Mon, 24 Sep 2007 16:08:31 +0000 http://www.simonwhatley.co.uk/?p=341#comment-2945 I dropped using isDefined() many moons ago as well, I thought it was common knowledge that isDefined() was inefficient and structKeyExists() was the way to go. Well, reading around and coming across <a href="http://www.placona.co.uk/blog/index.cfm/2006/11/30/Performance-Test-isDefined-x-structKeyExists" rel="nofollow">Marcos Placona's blog</a> where he has conducted a test, it turns out, to my amazement, structKeyExists() is slower then isDefined()! The key here is that isDefined() is super-fast when the scope exists, i.e. isDefined("session.userID"), but mega-slow if a non-existent scope is used, e.g. isDefined("unknownStruct.userID"). structKeyExists() is consistent regardless of what you provide. So, as long as you are asking for a SCOPED variable that is extant, isDefined will be faster on average! structKeyExists(), may be comparatively slower, but forces scoping, which is good practice. I dropped using isDefined() many moons ago as well, I thought it was common knowledge that isDefined() was inefficient and structKeyExists() was the way to go.

Well, reading around and coming across Marcos Placona’s blog where he has conducted a test, it turns out, to my amazement, structKeyExists() is slower then isDefined()!

The key here is that isDefined() is super-fast when the scope exists, i.e. isDefined(”session.userID”), but mega-slow if a non-existent scope is used, e.g. isDefined(”unknownStruct.userID”).

structKeyExists() is consistent regardless of what you provide.

So, as long as you are asking for a SCOPED variable that is extant, isDefined will be faster on average!

structKeyExists(), may be comparatively slower, but forces scoping, which is good practice.

]]> By: Russell Brown http://www.simonwhatley.co.uk/isdefined-vs-structkeyexists#comment-2944 Russell Brown Mon, 24 Sep 2007 11:58:15 +0000 http://www.simonwhatley.co.uk/?p=341#comment-2944 I also believe there is another performance factor with isDefined. When you execute something like isDefined("session.user") is checks other scopes for the key as well such as variables.session.user and request.session.user. I stopped using isDefined() all together years ago now and I'm not sure of a reason why to use it, unless maybe you don't know what scope the var will be in [variable, form, url]. I also believe there is another performance factor with isDefined. When you execute something like isDefined(”session.user”) is checks other scopes for the key as well such as variables.session.user and request.session.user. I stopped using isDefined() all together years ago now and I’m not sure of a reason why to use it, unless maybe you don’t know what scope the var will be in [variable, form, url].

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