How to Avoid Trailing Commas in Go Text Template Ranges?

Special Case Treatment for the Last Element of a Range in Go's Text Templates

When working with Go's text templates, handling the last element of a range can be tricky. Take, for instance, the task of creating a string like "(p1, p2, p3)". If you use a simple range loop, you may end up with an extra comma at the end, resulting in "(p1, p2, p3, )".

To address this, we can leverage a key feature of template ranges: the ability to declare two variables, separated by a comma. For example:

range $index, $element := .

In this case, $index represents the iteration index, and $element contains the current item in the range.

Using this trick, we can modify the template to:

{{range $index, $parameter := .}}{{$parameter}}{{$if $index}},{{end}}

Here, the $if statement checks whether $index is non-zero. If so, we display a comma. This approach ensures that the comma is only added before the last element, resolving the dangling comma issue.

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