[Tutor] string.Template

[Steven D'Aprano]

On 24/04/13 00:14, Albert-Jan Roskam wrote:
> Hello,
>
> Is there a better, *built-in* alternative for the code below? The recursion works,
> but it feels like reinventing the wheel.

What makes you think it is reinventing the wheel? The following looks like a perfectly sensible use for recursion. If your replacement strings themselves contain $-template strings, and you want to replace them as well, recursion seems like a good call.

Although, of course, the recursion may not converge on a single result. Consider what happens if you use the following replacement strings:

$spam -> $eggs
$eggs -> $spam



> import string
>
> def translate(template, *args):
>      """Recursively $-substitute <template> using <args> as a replacement"""
>      syntax = string.Template(template).substitute(*args)
>      if "$" in syntax:
>          return translate(syntax, *args)
>      return syntax
>
> template = """\
> Monty $surname
> $more
> """
> more = """\
> The quest for the holy $grail
> """
> surname="Python"
> grail="Grail"
> print translate(template, locals())



-- 
Steven