This is the final stage to the file system provided in previous recipes. A test of the seven other modules is shown here that demonstrates the abilities of this abstract design. Working disks is provided via a simple introductory menu, disk failure rate is fully customizable. A shell is provided with several commands that built in along with two programs that allow the creation and viewing of files.
Python, 327 lines
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from sys import exit
################################################################################
def main():
welcome()
loop()
def welcome():
print '+---------------------+'
print '| DISK DEMO |'
print '| by Stephen Chappell |'
print '+---------------------+'
def loop():
valid_disk = False
while True:
print
print 'PROGRAM MENU'
print '============'
print '(1) Create Disk'
print '(2) Load Disk'
if valid_disk:
print '(3) Save Disk'
print '(4) Use Disk'
while True:
try:
select = raw_input('Select: ')
except:
exit(0)
try:
select = int(select)
if 0 < select < 3 or (2 < select < 5 and valid_disk):
break
else:
print 'Select should be between 1 and',
if valid_disk:
print '4.'
else:
print '2.'
except:
print 'Select should be a number.'
print
if select == 1:
disk = create_disk()
disk.seed(False)
valid_disk = True
elif select == 2:
disk = load_disk()
disk.seed(False)
valid_disk = True
elif select == 3:
save_disk(disk)
else:
use_disk(disk)
def create_disk():
while True:
try:
print
print 'CREATE A DISK'
blocks = int(raw_input('BLOCKS: '))
size = int(raw_input('SIZE: '))
return DAL6(blocks, size)
except:
print 'INCORRECT VALUE'
def load_disk():
while True:
try:
print
print 'LOAD A DISK'
name = raw_input('FILENAME: ')
disk = DAL6(10, 10)
disk.load(name, False)
return disk
except:
print 'INVALID FILENAME'
def save_disk(disk):
while True:
try:
print
print 'SAVE THE DISK'
name = raw_input('FILENAME: ')
disk.dump(name)
break
except:
print 'INVALID FILENAME'
################################################################################
def use_disk(disk):
set_fail_rate(disk)
context = disk.new_context()
print
print 'CREATING A SHELL ...'
Shell(context)
print 'EXITING THE SHELL ...'
def set_fail_rate(disk):
while True:
try:
print
print 'SET DISK FAIL RATE'
probability = float(raw_input('PROBABILITY: '))
disk.fail(probability)
break
except:
print '0 <= PROBABILITY <= 1'
################################################################################
class Shell:
# The Users Interface
def __init__(self, context):
assert context.__class__ is Context
self.__context = context
self.__commands = ['chdir', 'getcwd', 'listdir', \
'mkdir', 'rmdir', 'remove', 'exit']
self.__programs = ['type', 'edit']
print 'Welcome to DAL'
print '=============='
while True:
try:
prompt = raw_input('>>> ')
except:
continue
if prompt == 'help':
print 'COMMANDS:'
print ' chdir: change current working directory'
print ' getcwd: get current working directory'
print ' listdir: display directory contents'
print ' mkdir: make a new directory'
print ' rmdir: remove an old directory'
print ' remove: remove a file'
print ' exit: terminates this shell'
print 'PROGRAMS:'
print ' type: display the contents of a file'
print ' edit: create a new file'
else:
prompt = prompt.split(' ')
command = prompt[0]
path = ' '.join(prompt[1:])
if command in self.__commands:
if command == 'chdir':
self.__chdir(path)
elif command == 'getcwd':
self.__getcwd()
elif command == 'listdir':
self.__listdir(path)
elif command == 'mkdir':
self.__mkdir(path)
elif command == 'rmdir':
self.__rmdir(path)
elif command == 'remove':
self.__remove(path)
else:
break
elif command in self.__programs:
if command == 'type':
try:
Type(self.__context, path)
except:
print 'Type has crashed.'
else:
try:
Edit(self.__context, path)
except:
print 'Edit has crashed.'
else:
print repr(command), 'is an unrecognized command or program.'
# Changes Current Directory
def __chdir(self, path):
try:
if self.__context.exists(path):
if self.__context.isdir(path):
self.__context.chdir(path)
else:
print 'PATH IS NOT A DIRECTORY'
else:
print 'PATH DOES NOT EXIST'
except:
print 'COULD NOT CHANGE CURRENT WORKING DIRECTORY'
# Get Current Directory
def __getcwd(self):
print self.__context.getcwd()
# Lists Directory Contents
def __listdir(self, path):
try:
if self.__context.exists(path):
if self.__context.isdir(path):
names = self.__context.listdir(path)
for name in names:
if len(name) > 40:
temp = name[:37] + '...'
else:
temp = name
print temp + ' ' * (41 - len(temp)) + '<>',
if path:
temp = path + ' ' + name
else:
temp = name
if self.__context.isdir(temp):
print 'DIR'
else:
print 'FILE'
else:
print 'PATH IS NOT A DIRECTORY'
else:
print 'PATH DOES NOT EXIST'
except:
print 'COULD NOT DISPLAY DIRECTORY CONTENTS'
# Create New Directory
def __mkdir(self, path):
try:
if self.__context.exists(path):
if self.__context.isfile(path):
print 'NAME IS ALREADY IN USE'
else:
print 'THE DIRECTORY ALREADY EXISTS'
else:
self.__context.mkdir(path)
except:
print 'DIRECTORY COULD NOT BE CREATED'
# Remove A Directory
def __rmdir(self, path):
try:
if self.__context.exists(path):
if self.__context.isdir(path):
self.__context.rmdir(path)
else:
print 'PATH IS NOT A DIRECTORY'
else:
print 'PATH DOES NOT EXIST'
except:
print 'DIRECTORY COULD NOT BE REMOVED'
# Remove A File
def __remove(self, path):
try:
if self.__context.exists(path):
if self.__context.isfile(path):
self.__context.remove(path)
else:
print 'PATH IS NOT A FILE'
else:
print 'PATH DOES NOT EXIST'
except:
print 'FILE COULD NOT BE REMOVED'
################################################################################
class Type:
# Display A File
def __init__(self, context, path):
assert context.__class__ is Context
assert type(path) is str
try:
print context.file(path, 'r').read()
except:
print 'FILE COULD NOT BE FOUND'
################################################################################
class Edit:
# Create A File
def __init__(self, context, path):
assert context.__class__ is Context
assert type(path) is str
while True:
try:
option = raw_input('write OR append? ')
assert option == 'write' or option == 'append'
break
except:
pass
if option[0] == 'a':
if context.exists(path):
if context.isfile(path):
self.__menu(context, path, 'a')
else:
print 'PATH IN NOT A FILE'
else:
print 'FILE DOES NOT EXIST AND WILL NOT BE CREATED'
else:
try:
if context.exists(path):
if context.isfile(path):
self.__menu(context, path, 'w')
else:
print 'PATH IS NOT A FILE'
else:
self.__menu(context, path, 'w')
except:
print 'FILE COULD NOT BE CREATED'
# Display A Menu
def __menu(self, context, path, mode):
file_object = context.file(path, mode)
data = self.__edit()
file_object.write(data)
file_object.close(False)
# Get New Lines
def __edit(self):
lines = []
while True:
try:
lines.append(raw_input())
except:
break
return '\n'.join(lines)
################################################################################
if __name__ == '__main__':
main()
|
This is the last recipe is a series of recipes demonstrating an abstract file system. dal_6.py can be found at http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/492214
Note: The files presented in these recipes are not guaranteed to be without errors. Not all functions have been implemented (primarily those for checking errors). These files have had rather limited testing and were written for an OS class.
Tags: files
