dynamic string substitution using string.Template in Python

Question

Is it possible to do dynamic string substitution with Python's string.Template ? More precisely I don't want to replace occurrences of identifiers with results of functions, e.g.

from string import Template

f = lambda s: "123"

templateString = """first line: $replaceme
2nd line "$replaceme" """

s = Template(templateString).substitute(replaceme=f)

Instead of evaluating f its string representation is used:

first line: <function <lambda> at 0x7fb0367e3488>
2nd line "<function <lambda> at 0x7fb0367e3488>"

Any ideas how to do substitution with the result of f ?

BrenBarn · Accepted Answer · 2015-11-28 20:05:04Z

2

You need to call f by doing f(). f means the function; f() means its return value.

answered Nov 28, 2015 at 20:05

BrenBarn

253k39 gold badges421 silver badges392 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Stefan Armbruster Over a year ago

If using f() the evaluation is done once for all occurrences of replaceme. My intention was to call f for each occurrence.

BrenBarn Over a year ago

@StefanArmbruster: Pretty sure that's not possible with the way you're doing it. The placeholder in the template has to specify a static value, not an expression, so if you use $replaceme both times, you have to get the same value both times.

Collectives™ on Stack Overflow

dynamic string substitution using string.Template in Python

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related