ADF Dynamic Expression - concat/if missing period

Question

In what I would have thought was relatively simple code, I can't figure out what the issue is with adding another string to my list of concatenations

Below is the code that I currently have and I get expected output

@concat('start ', if(equals(coalesce(pipeline().parameters.p_source_object.TYPE,''),'x'), 'a', 'b'))

However, I want to add more strings to the concatenation but when I add a comma between the two end brackets like so

@concat('start ', if(equals(coalesce(pipeline().parameters.p_source_object.TYPE,''),'x'), 'a', 'b'), )

I get an "Invalid" error with "Missing period" message. If I put a period before the comma, the error goes away (but obviously invalid syntax)

What is it expecting here?

On a related note, is there a better way to concatenate while also doing some functions that output strings? It's the most unintuitive interface imaginable (Microsoft do seem to pride themselves in the ridiculous!)

Hoping someone can find my sanity for me!

Answer 1

In the end, I completely reworked it avoiding the layers... however, I have discovered a resolution

@{concat('start ', if(equals(coalesce(pipeline().parameters.p_source_object.TYPE,''),'x'), 'a', 'b'), 'dd')}

While it doesn't stand out as to how... there's a space at the start of the line, this stops it being considered "Dynamic content" but instead uses string interpolation