erict1689 a écrit :
I am writing this program in which I open up a file and update that
information but to a new file. I already have a global variable for
it
A global variable ??? WHY ???
but how do I go about creating an openable file in the source code?
It's in the FineManual(tm)
If it helps here is what I have:
def startUp():
# Purpose: opens files and print report headings
global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
payFileUpdated, newYTD, currentPay
payFile=open("payroll.txt", "r")
payFile.readline()
def readRecord():
# Purpose: reads a record
global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
payFileUpdated, newYTD, currentPay
employeeRec = payFile.readline()
if employeeRec == "":
eof = True
else:
# parse file line for record fields and format/convert for
final output
empName = employeeRec[0:25].strip()
previousYTD = float(employeeRec[25:40])
payRate = float(employeeRec[40:55])
hoursWorked = float(employeeRec[55:70])
recordCount += 1
eof = False
def writeRecord():
# Purpose: writes the updated record to the output file
#Parameter
global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
payFileUpdated, newYTD, currentPay
def processRecords():
# Purpose: loops through input file and processes each record
global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
payFileUpdated, newYTD, currentPay
while not eof:
calculatePay()
printReportLine()
writeRecord()
readRecord()
def calculatePay():
# Purpose: calculates pay and updated YTD
# Return values: float - calculated pay, float - updated YTD amount
global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
payFileUpdated, newYTD, currentPay
def printReportLine():
# Purpose: prints employee pay information
# Parameters passed: float - calculated pay, float - updated YTD
amount
global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
payFileUpdated, newYTD, currentPay
def closeUp():
# Purpose: end of program housekeeping
global empName, previousYTD, payRate, hoursWorked, recordCount,
eof, payFile, \
payFileUpdated, newYTD, currentPay
payFile.close()
payFileUpdated.close()
print "\nNumber of records in the file was",recordCount
OMG ! Good Ole Almighty Procedural Programming (With Lots Of Useless
Gobals(tm)) is back ! Where have you been these 20 last years ???
Any and all help is appreciated.
Err... Python is not BASIC ?-)
Not tested, but you may be interested in another approach (which *also*
contains the answer to your question)...
import sys
def parse_field(slice, transform, line):
return transform(line[slice].strip())
# key => processing function mapping
INFIELDS = dict(
emp_name=partial(parse_field, slice(0,25), lambda x : x),
previous_ytd=partial(parse_field, slice(25,40), float),
payrate=partial(parse_field, slice(40,55), float),
hoursworked=partial(parse_field, slice(55,70), float)
)
def parse_line(line):
"""
parse a line and return a record (key=>value mapping) from it
"""
return dict(
(fname, parse(line))
for fname, parse in INFIELDS.items()
)
def calculate_pay(record):
"""
calculate pay etc and returns updated record with additional fields
"""
# dummy code
record['yadda'] = "yadda"
return record
def format_record(record):
"""
returns a formatted string for output
"""
# dummy code, assuming output is csv like format
return "%(emp_name)s;%(payrate)s;%(yadda)s" % record
def print_report_line(record):
""" print tracing / debugging info on stderr """
print >> sys.stderr, record
def process_line(lineno, line):
"""
parse a line, compute pay, and return a nicely formatted output
"""
source = parse_line(line)
source['num_record'] = lineno
dest = calculate_pay(source)
print_report_line(dest)
return format_record(dest)
def main(infile, outfile):
"""
process lines from infile and write the result to outfile
"""
for lineno, line in enumerate(infile):
line = line.strip()
if line:
print >> outfile, process_line(lineno, line)
if __name__ == '__main__':
#
# the boring part... would better be done using optparse...
#
# we expect two optional params:
# 1/ the path to an input file - default to stdin
# 2/ the path to an output file - default to stdout
#
try:
infile = open(args[0])
except IndexError:
infile = sys.stdin
except IOError, e:
sys.exit(
"could not open file %s for reading : %s" \
% (args[0], e)
)
try:
outfile = open(args[1], 'w')
except IndexError:
outfile = sys.stdout
except IOError, e:
if infile is not sys.stdin:
infile.close()
sys.exit(
"could not open file %s for writing : %s" \
% (args[1], e)
)
try:
# processing
main(infile, outfile)
finally:
# housekeeping...
if infile is not sys.stdin:
infile.close()
if outfile is not sys.stdout:
outfile.close()
HTH
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