Why delimiters blocks must have at least two characters ?

[raplonu]

I'm working on a CMake tool that needs to handle template variables with the following syntax: ${<macro-name>} (I also have more complex cases, but let's ignore those for now).

I tried to configure Askama but got this error:

error: delimiters must be at least two characters long. The closing expression delimiter ("}") is too short

Reading the Askama documentation, I came across this note:

Values must be at least two characters long

I'm new to this crate, and I'm curious, why is that restriction in place?

As a follow-up: is it really necessary to apply this restriction to the *_end delimiter as well?