Are Multiple Layout TBBs okay?

Question

Using multiple layout TBBs in a modular template makes multiple Output items in the Package, which I understand act as a stack of text/html items named Output.

Is it a bad idea to use this modular templating feature to manage various presentations for a given modular template? I suspect the TBB that chooses which Output to keep would be rather "hackish."

In other words, is there a way to choose a layout TBB at publish time?

Alternatively, using a single layout TBB, we can use conditional logic to show/hide certain markup.

<!-- TemplateBeginIf cond="somecondition" -->
Do something...
<!-- TemplateEndIf -->

The use case would be minimizing localization of templates across websites, devices, or other channels. We do this easily with fields saved in config components or publication metadata--I'm trying to find the equivalent for markup managed in the CMS (edit: without localizing templates to be clear).

Answer 1

The only time I used stacked DWT TBBs in a compound template was when I needed to iterate over nested lists.

I would use 2 DWT TBBs:

• the first one would only contain the markup for the 'inner' loop;
• the second for the actual output;

There would be a C# TBB in-between the DWTs that processes the first DWT (the inner loop markup) and prepares some variables in the package. The second DWT would then execute and it would include the results prepared by the C# TBB.

Using a similar approach, one could choose which DWT to include in the final output. However, note that all DWTs will be executed, potentially resulting in a performance hit.

There is no way to include a DWT inside another DWT (at least not by using OOTB DWT TBB syntax).

Regarding minimizing template localisation -- I don't think I would ever localize templates. Instead, I would probably:

• parameterise the TBBs (including DWT TBBs) such that I could reuse them in different contexts by simply changing a parameter/metadata;
• implement Content Delivery logic to change the generated markup (coming from the same TBB) on the Presentation server based on the targeted channel, device, media...;

Answer 2

It is sometimes appropriate to have multiple Output items in the package. For instance, Outbound E-mail does this when sending Mailings. The first Output contains the plain-text variation and the second contains the HTML variation. The two are then combined into one depending on the Contact's preferences (plain-text only, HTML only, or multi-part which contains both versions). It's always the last Output item in the package that will be used, by the way.

I would generally discourage the use unless you actually have two representations of the output, as mentioned above.