i don't know how easy or hard this would be to do. i want to have a function that gets a sting from a caller and make it be like an f-string and do it it the context of the caller even though the caller does not have it as an f-string literal. it might be read from a file, for example. the str can have "{n}" in it and the n i gets is the caller's variable n. anyone know how to do this?
The following worked for me
n = 48
def func(fstring):
n = 100
return eval('f' + repr(fstring))
if __name__ == '__main__':
result = func("There are {n} items")
print(result)Output:
There are 100 items
i want the caller's context. so, 48 would be expected.
It is very difficult because I'm typing with my cat on my knees but this works
import sys
n = 48
def eval_fstring(fstring, globals=None, locals=None):
"""Evaluate an fstring
arguments:
fstring: the fstring to evaluate
globals, locals: same meaning as in the eval() function
returns:
the string evaluated
"""
f = sys._getframe(1)
try:
if globals is None:
globals = f.f_globals
elif locals is None:
locals = globals
if locals is None:
locals = f.f_locals
return eval('f' + repr(fstring), globals, locals)
finally:
del f, globals, locals
def foo():
result = eval_fstring("There are {n} items")
print(result)
def bar():
n = 300
result = eval_fstring("There are {n} items")
print(result)
if __name__ == '__main__':
foo()
bar()Output:
There are 48 items
There are 300 items