fuglyducky wrote:
I am a complete newbie to Python (and programming in general) and I
have no idea what I'm missing. Below is a script that I am trying to
work with and I cannot get it to work. When I call the final print
function, nothing prints. However, if I print within the individual
functions, I get the appropriate printout.
Am I missing something??? Thanks in advance!!!!
################################################
# Global variable
sample_string = ""
def gen_header(sample_string):
HEADER = """
mymultilinestringhere
"""
sample_string += HEADER
return sample_string
def gen_nia(sample_string):
NIA = """
anothermultilinestringhere
"""
sample_string += NIA
return sample_string
gen_header(sample_string)
gen_nia(sample_string)
print(sample_string)
sample_string = gen_header(sample_string)
sample_string = gen_nia(sample_string)
print sample_string
That should work.
I guess you made an error thinking that
sample_string += HEADER
would change the value of the given parameter. It does not. The value is
changed only for sample_string within the function This is the case for
any immutable object (strings are immutable) in Python.
Example:
class AMutable(object):
def __init__(self):
self.description = 'I am X'
myString = 'I am a immutable string' # an immutable object
myMutable = AMutable() # a mutable object
def bar(myMutable):
myMutable.description = 'I am Y' # change the attribute description
of the object
def foo(aString):
aString = 'fooooooooo' # will have no effect outside the function
print 'before calling bar: ', myMutable.description
bar(myMutable)
print 'after calling bar: ', myMutable.description
print 'before calling foo: ', myString
foo(myString)
print 'after calling foo: ', myString
>
before calling bar: I am X
after calling bar: I am Y
before calling foo: I am a immutable string
after calling foo: I am a immutable string
cheers,
JM
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