Feature #15538
Updated by kke (Kimmo Lehto) almost 6 years ago
In `Erb`, would it be possible to add a new trim mode that would indent the following content to match the depth of the tag? The tag could for example be `<%|` and it would be enabled using `Erb.new(template, trim_mode: '|')`
## Reason
Something like this would be easy to follow:
``` ruby
1
<%- [2, 3, 4].each do |num| -%>
<%- unless num == 3 -%>
<%= num %>
<%- end -%>
<%- end -%>
5
```
But unfortunately it will render with "extra" indentation:
```
1
2
4
5
```
Currently, to avoid this, you have to write your template using either no indentation:
```
1
<%- [2, 3, 4].each do |num| -%>
<%- unless num == 3 -%>
<%= num %>
<%- end -%>
<%- end -%>
5
```
Or a weird jumpy indentation:
```
1
<%- [2, 3, 4].each do |num| -%>
<%- unless num == 3 -%>
<%= num %>
<%- end -%>
<%- end -%>
5
```
With the `|` trim mode it could be written as:
```ruby
1
<%|- <%| [2, 3, 4].each do |num| -%>
<%- unless num == 3 -%>
<%= num %>
<%- end -%>
<%|- <%- end -%>
5
```
And it would output as desired without the "extra" indentation:
```
1
2
4
5
```
## Using with `=`
It would also be handy if the `|` could be used with `<%=`, perhaps `<%|=`, this would be excellent for example when templating YAML's:
```yaml
<%- bar_content = "- abc\n- " -def" -%>
foo:
bar:
<%|= bar_content |%> %>
```
Which would produce something like:
```yaml
foo:
bar:
- abc
- def
```
Instead of the invalid YAML:
```yaml
foo:
bar:
- abc
- def
```
Currently there's no way to accomplish this without manually counting the leading spaces and using something like:
```yaml
<%- bar_content = "- abc\n- " -def" -%>
foo:
bar:
<%= bar_content.gsub(/(?<!\A)^(?!$)/m, ' ' * 4) %>
```