Python String Templates

Question

We are using string template to replace some values in Python String by supplying a dict . It works fine . However despite using safe_substitute this below code doesnt work as expected . Any idea why ?

from string import Template 
obj = Template("$$Tag$$") 
obj.safe_substitute({}) 

Output : '$Tag$' Expected : '$$Tag$$' 
(As there is no value to replace in the dict supplied .)

This same issue happens for '####' if I make '##' as the delimiter . Anyone knows why is it ignoring an extra delimiter ? Just trying to understand what happens under the hood .

Answer 1

From docs :

$$ is an escape; it is replaced with a single $ .

If you want double $ , then you can use something like:

>>> obj = Template("$$$$Tag$$$$")
>>> obj.safe_substitute({})
'$$Tag$$'
>>> obj.safe_substitute({'Tag':1})
'$$Tag$$'
>>> obj = Template("$$$Tag$$$") #First $ escapes the second $
>>> obj.safe_substitute({'Tag':1})
'$1$$'

Answer 2

From the doc :

"$$" is an escape; it is replaced with a single "$".

Answer 3

You have to put two dollar signs for each one that you want in the output:

>>> Template('$$$$Tag$$$$').substitute()
'$$Tag$$'