Lisp type languages usually provide an abstraction which allows you to open a string as a file, and then print to it using any function which can normally print to a file. When you close the string you can recuperate the string that was printed.
Does something like this exist for python?
It probably would like something like this:
f = open_string_as_output()
f.write("hello")
if some_condition:
f.write(" ")
g(f) # allow g to write to the sting if desired
f.close()
str = f.get_string()
There is a class called StringIO, which does what you described.
import io
string_out = io.StringIO()
string_out.write('Foo')
if some_condition:
string_out.write('Bar')
string_out.getvalue() # Could be 'Foo' or 'FooBar'
the io module allows exactly that: use the versatility of the print() function with the flux redirected to a string.
from io import StringIO
output = StringIO()
print("Hello World!", file=output)
print(f"I have written so far this to my string: {output.getvalue()}", file=output)
result = output.getvalue()
print(result)
outputs:
Hello World!
I have written so far this to my string: Hello World!
You cannot overuse this technique. See this example:
from io import StringIO
garbage = StringIO()
def foo(stuff, out_flux=None):
''' A function that prints stuff but you need to mute from time to time. '''
result = stuff
print(result, file=out_flux)
# normal use
foo(10) # prints 10
# muted use
foo(10, out_flux=garbage) # prints nothing
print(garbage.getvalue()) # prints whatever was collected so far
There is somthing called a string stream which might help you.
import io # the library for input and output
words = ["PEPPERS", "SWEET", "BELL", "AMPIUS", "PKT" "$2.00"]
str_strm = io.StringIO()
# `sep` is `separator`
# `end` is `end of line`
print(*iter(words), sep="...", end="\r\n", file=str_strm)
final_result = str_strm.getvalue()
str_strm.close() # a close the string stream to avoid a memory leak
However, there are simpler ways to print to a string.
def print2str(*args, sep=' ', end='\n') -> str:
it = iter(str(arg) for arg in args)
result = sep.join(it) + end
return result
