I’m sure people have mentioned this before, I develop in EE alot and I am always running into the same problem of not being able to create any dynamic variables.  If I want to decide which categories to show based on a segment, then it would be nice to simply have a variable I could assign within a loop to do that.  I run into this on almost every project and I usually have two options, write sloppy EE code that has my code recopied for every instance within a If then Else statement or use PHP, which I really try to avoid doing.  It wouldn’t have to be very robust, but it would add a great degree of functionality if we could just assign dynamic string vars.  I bet there’s a good reason this isn’t already a feature, but I know several people who do EE development, and they’ve run into the same problem. 
BTW-  EE is an awesome product!

The reason is two-fold, Kev-O, and I’ll try to explain.

First, show me any conditional and I can give you an example of it used in a context of where the developer does want it parsed and evaluated in time to create a variable, and another where they would not want it parsed at that time.  Because people wish to do so many things in the templates, EE can only be predictive to a degree within the confines of things taking place in a particular order.

Second is that with thoughtful template design and URL structure, that type of assignment is often unnecessary, as ExpressionEngine has many ways to automatically constrain tag output with semantic and useful URLs.  In the cases that it does not meet your needs, these segment conditionals you refer to can simply call a shared embedded template, passing the necessary variable via an embed variable.  The result is that you end up with cleaner looking templates, and have less duplicated code.

Yeah right on, I get it.  Hadn’t thought of using embedded templates for conditional segments, thats a really good idea.  Thanks for the explanation…

Ah ha.. embedded templates as a sort of a little call back routine. Isn’t this expensive in EE template passing?

Hinterlands - 06 July 2008 11:03 PM

Ah ha.. embedded templates as a sort of a little call back routine. Isn’t this expensive in EE template passing?

Not in normal circumstances.  Turn on your template parsing log and you’ll be able to see the time and memory increase.  Where it can become expensive is when you start doing some really silly things with embeds, such as a weblog entries tag within an template that gets embedded a hundred or so times in a loop.