Looking for very light weight template library (not framework)

[Duncan Booth]

"Malcolm Greene" <python at bdurham.com> wrote:

> New to Python and looking for a template library that allows Python
> expressions embedded in strings to be evaluated in place. In other 
words
> something more powerful than the basic "%(variable)s" or "$variable"
> (Template) capabilities.
> 
> I know that some of the web frameworks support this type of template
> capability but I don't need a web framework, just a library that
> supports embedded expression evaluation.

You could try using the Template class:

>>> from string import Template
>>> class EvalTemplate(Template):
	idpattern = '[^{}]+'

	
>>> class EvalDict(dict):
	def __getitem__(self, name):
		if name in self:
			return dict.__getitem__(self, name)
		return eval(name, globals(), self)

	
>>> class Invoice:
	def __init__(self, total):
		self.total = total

		
>>> i = Invoice(42)
>>> template = EvalTemplate("The total cost is ${invoice.total}")
>>> template.substitute(EvalDict(invoice=i))
'The total cost is 42'

The usual caveats about using 'eval' apply (maybe it should be called 
EvilDict), and I'm sure you could override substitute/safe_substitute to 
construct the EvalDict transparently.