Is there a way to fail a template silently?

[felipecrs]

I'm doing this:

{{- $chezmoiForce := or (has "--force" .chezmoi.args) (has "--force=true" .chezmoi.args) -}}

{{ $name := "" -}}
{{- if hasKey . "name" -}}
{{-   $name = .name -}}
{{- end -}}
{{- if and stdinIsATTY (not $chezmoiForce) -}}
{{-   $question := "What is your full name" -}}
{{-   if $name -}}
{{-     $name = promptString $question $name -}}
{{-   else -}}
{{-     $name = promptString $question -}}
{{-   end -}}
{{-   if $name -}}
{{-     writeToStdout (printf "✔ Name set as '%s'\n" $name) -}}        
{{-   else -}}
{{-     writeToStdout "❌ Invalid name, please start over.\n" -}}
{{-     fail "" -}}
{{-   end -}}
{{- end -}}

But it fails like:

❯ chezmoi init --data=false
What is your full name?
❌ Invalid name, please start over.
chezmoi: template: chezmoi.yaml:18:8: executing "chezmoi.yaml" at <fail "">: error calling fail:

It would be cool if I could simply fail with a stdout message, rather than a "debug" mesage.

[twpayne]

I don't think this is possible. As mentioned in other discussions and issues, text/template is a templating language designed to render static data, not a programming language.

[felipecrs]

I don't think this is possible.

May I suggest a new initTemplateFunc called failWithStdout *message* or just failSilently?

text/template is a templating language designed to render static data, not a programming language.

I don't see how this is relevant here.

[twpayne]

May I suggest a new initTemplateFunc called failWithStdout *message* or just failSilently?

I don't think this is possible. text/template.Template.Execute either succeeds (in which case it returns nil) or fails (in which case it returns an error). There is no concept of early termination.

text/template is a templating language designed to render static data, not a programming language.

I don't see how this is relevant here.

It's relevant because programming languages have richer control flow, e.g. while loops, returns, etc. The template in the original post is not rendering static data, it's trying to run an interactive loop.

[felipecrs]

I don't think this is possible. text/template.Template.Execute either succeeds (in which case it returns nil) or fails (in which case it returns an error). There is no concept of early termination.

I think it's possible by returning a specific error from the new function and treating it before exiting chezmoi to handle the exit message. No?

It's relevant because programming languages have richer control flow, e.g. while loops, returns, etc. The template in the original post is not rendering static data, it's trying to run an interactive loop.

The loop itself is being discussed at #1671. There is no loop here.

Regardless, sprig provides the fail function just because of it: flow control. I'm not reinventing the wheel as sprig already provides it, I just want to improve the message.

[twpayne]

I think it's possible by returning a specific error from the new function and treating it before exiting chezmoi to handle the exit message. No?

You're right. #1674 should implement this.

[twpayne]

With #1674, failing silently can be achieved with {{ exit 0 }}. chezmoi must be built with Go 1.17 or later for this to work.

[twpayne]

With #1674, chezmoi now has an exit template function which allows you to fail templates silently with {{ exit 0 }}. This function is only available when generating the initial config file (#1771).