Avoid using a tag as parameter value for another tag

gistfile1.md

Avoid using a tag as parameter value for another tag in ExpressionEngine

Instead of this:

{exp:channel:entries param="{exp:some:plugin}"}
	...
{/exp:channel:entries}

Either use an embed, like this:

{embed="channel/entries" value="{exp:some:plugin}"}

{!-- And the embedded template: --}

{exp:channel:entries param="{embed:value}"}
	...
{/exp:channel:entries}

Or use the plugin as a tag pair (if supported), like this:

{exp:some:plugin parse="inward"}
	{exp:channel:entries param="{plugin_value}"}
		...
	{/exp:channel:entries}
{/exp:some:plugin}

Or add your own suggestions below.

You don't say why it's bad to pass a tag as a parameter, so here goes:

• you need to use parse="inward" for it to work at all. That makes EE create a new instance of the template parser to parse each parameter, whether it's the parameter containing your tag or not. More parameters = more overhead.
• if your passed tag outputs a quote character or a line break, the EE parser will choke.
• sometimes EE will choke if the parent tag parameters are separated onto new lines when using parse="inward"

Despite these caveats, I still think it's a useful technique for certain things and has far less overhead than an embed.

@jeromecoupe: EE provides a method for add-on devs to easily parse variables. But that method will automatically add {count}, {total_results} and {switch} to the mix. That's why there's conflicts. Not much you can do about that without getting complicated.

@croxton: The main reason why it's bad, is that it will not work in all cases. It might work in some, but inconsistency is a big pain to explain.