Bypass code block without conditional

tips & tricks
1

Typical construct:

{{ $doThis := true }}

{{ if $doThis }}
  {{ warnf "I did it" }}
{{ else }}
  {{ warnf "I didn't do it" }}
{{ end }}

But that’s a simple example. With multiple and/or nested conditions, adding another condition can make the code difficult to read or maintain. What we really, really want is:

{{ $doThis := true }}

{{ if $doThis }}
  {{ warnf "I did it" }}
  {{ exit }}    <-- pseudo code; this template function does not exist
{{ end }}
{{ warnf "I didn't do it" }}

There’s a proposal to add this functionality to Go’s template packages, but the effort has died on the vine.

But you can get the desired behavior by wrapping the code in a loop that executes once, using the break statement:

{{ $doThis := true }}

{{ range seq 1 }}
  {{ if $doThis }}
    {{ warnf "I did it" }}
    {{ break }}
  {{ end }}
  {{ warnf "I didn't do it" }}
{{ end }}

It’s a bit clumsy, but in some situations the resulting code is more manageable.

7 Likes
2

Thanks for the tip @jmooring.