?
=?ISO-8859-1?Q?Andr=E9_Roberge?=
Hi all,
I posted the following on the python tutor list 3 days ago ... and
haven't heard a peep from anyone - which is highly unusual on that list.
[Apologies for the slightly longer post due to code
with tests cases included at the end .]
====================
I have created a "severely restricted" environment within with
users can learn the basics of programming in Python.
[note: eval, exec, chr, input, raw_input are not allowed.]
Within that environment, I want to have the user test the five
valid forms that an import statement can have, by attempting to
import a fake module whose name is "useful". Other "import"
statements are disallowed.
1. import useful
2. from useful import *
3. from useful import valid_function1 [, valid_function2, ...]
4. from useful import valid_function as better_named_function
5. import useful as not_so_useful_after_all
As far as I can tell, the following works, but it looks rather
"clunky" to me. My *very limited* experience with the
"re" module may have something to do with this.
Any suggestion would be most welcome.
André
=======Here's the code formatted (fingers crossed) to work if cut and
pasted from email =========================
# test_import.py
import re
isolate_words = re.compile(r'\W+') # used with .split()
# pre-compiled some regular expression with allowable use of "import"
imp_use = re.compile('^import useful', re.MULTILINE)
imp_use_as = re.compile('^import useful as (\w+)', re.MULTILINE)
from_use_imp_star = re.compile('^from useful import \*', re.MULTILINE)
from_use_imp_names = re.compile(
"^from useful import (\w+(,[ ]*\w+)*)",
re.MULTILINE)
from_use_imp_as = re.compile(
"^from useful import (\w+) as (\w+)",
re.MULTILINE)
# In the following, "r" is used so that \b identifies a word boundary,
# and is not interpreted as backslash by Python.
import_misuse = re.compile(r'\bimport\b', re.MULTILINE)
# use to commenting out the valid "import" statements after processed.
comment_from = re.compile('^from ', re.MULTILINE)
comment_import = re.compile('^import ', re.MULTILINE)
# Create a fake module which can be "imported"
right = "turn_right():\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" turn_left()\n\n"
around = "turn_around():\n"+\
" turn_left()\n"+\
" turn_left()\n\n"
up_east = "climb_up_east():\n"+\
" turn_left()\n"+\
" move()\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" turn_left()\n\n"
up_west = "climb_up_west():\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" move()\n"+\
" turn_left()\n\n"
down_west = "climb_down_west():\n"+\
" turn_left()\n"+\
" move()\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" turn_left()\n\n"
down_east = "climb_down_east():\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" move()\n"+\
" turn_left()\n\n"
commands = {'turn_right': right, 'turn_around': around,
'climb_up_east': up_east, 'climb_up_west': up_west,
'climb_down_east': down_east, 'climb_down_west': down_west}
#=== end of info on fake module
# The following fonctions are helper functions to
# process the "import" statement:
# they add the appropriate "imported commands"
# before the "import" statement,
# before commenting out (by pre-pending #) the "import" statement line
def import_useful():
added_text = ''
for instruction in commands:
new = "def " + 'useful.' + commands[instruction]
added_text += new
return added_text, True
def from_useful_import_star():
added_text = ''
for instruction in commands:
new = "def " + commands[instruction]
added_text += new
return added_text, True
def import_useful_as(syn):
added_text = ''
for instruction in commands:
new = "def " + syn + '.' + commands[instruction]
added_text += new
return added_text, True
def from_useful_import_names(names):
added_text = ''
for instruction in isolate_words.split(names):
try:
new = "def " + commands[instruction]
except:
print instruction, " not found in module useful"
added_text += new
return added_text, True
def from_useful_import_as(name, syn):
added_text = ''
try:
new = "def " + commands[name].replace(name, syn)
except:
print name, " not found in module useful"
added_text += new
return added_text, True
def process_no_import():
added_text = ''
return added_text, True
# the basic processing function
def process_file(file_text):
if imp_use_as.search(file_text): # look for "import useful as ..."
syn = imp_use_as.findall(file_text)
added_text, safe_import_flag = import_useful_as(syn[0])
file_text = comment_import.sub('#import ', file_text)
elif imp_use.search(file_text): # perhaps the "as ..." part is
# missing
added_text, safe_import_flag = import_useful()
file_text = comment_import.sub('#import ', file_text)
elif from_use_imp_star.search(file_text):
added_text, safe_import_flag = from_useful_import_star()
file_text = comment_from.sub('#from ', file_text)
elif from_use_imp_as.search(file_text):
names = from_use_imp_as.findall(file_text)
name = names[0][0]
syn = names[0][1]
added_text, safe_import_flag = from_useful_import_as(name, syn)
file_text = comment_from.sub('#from ', file_text)
elif from_use_imp_names.search(file_text):
names = from_use_imp_names.findall(file_text)
added_text, safe_import_flag = \
from_useful_import_names(names[0][0])
file_text = comment_from.sub('#from ', file_text)
elif import_misuse.search(file_text):
safe_import_flag = False
file_text = '' # remove it all
added_text = '# import keyword used improperly'
else:
added_text = ''
safe_import_flag = True # nothing found
added_text += file_text
return added_text, safe_import_flag
#======== Various test cases == only self-testing stuff follows
test1 = '''# test1: no import
other instructions'''
test2 = '''# test2
import useful
other instructions'''
test3 = '''# test3
from useful import *
other instructions'''
test4 = '''# test4
from useful import turn_around, turn_right, climb_up_east
other instructions'''
test5 = '''# test5
import useful as use
other instructions'''
test6 = '''# test6
from useful import turn_right
other instructions'''
test7 = '''# test6
from useful import turn_right
other instructions'''
test8 = '''# test8
from useful import turn_right as vire_a_droite
other instructions'''
test9 = '''# test9
import sys
other instructions'''
test10 = '''# test10
from sys import *
other instructions'''
test11 = '''# test11
# import in comment
import useful
other instructions'''
test12 = '''# test12
important test'''
test13 = '''# test 13
import useful
# import sys
other instructions'''
test14 = '''# test14: two import statements; good one first
import useful
import sys
other instructions'''
test15 = '''# test15: two import statements; bad one first
import useful
import sys
other instructions'''
test16 = '''# test16: bad import, indented
import sys
other instructions'''
if __name__ == "__main__":
print "=====begin 1: no import======"
added_text, safe_import_flag = process_file(test1)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 2======"
added_text, safe_import_flag = process_file(test2)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 3======"
added_text, safe_import_flag = process_file(test3)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 4======"
added_text, safe_import_flag = process_file(test4)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 5======"
added_text, safe_import_flag = process_file(test5)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 6======"
added_text, safe_import_flag = process_file(test6)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 7======"
added_text, safe_import_flag = process_file(test7)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 8======"
added_text, safe_import_flag = process_file(test8)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 9: import not allowed======"
added_text, safe_import_flag = process_file(test9)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 10: import not allowed======"
added_text, safe_import_flag = process_file(test10)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 11: import ok in text and import in comment======"
added_text, safe_import_flag = process_file(test11)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 12: word used: important; should be ok ======"
added_text, safe_import_flag = process_file(test12)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 13: 2nd import in comment ======"
added_text, safe_import_flag = process_file(test13)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 14: two import statements; good one first ======"
added_text, safe_import_flag = process_file(test14)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 15: two import statements; bad one first ======"
added_text, safe_import_flag = process_file(test15)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 16: bad import, indented ======"
added_text, safe_import_flag = process_file(test16)
print added_text
print "safe import flag = ", safe_import_flag
print "====="
wait = input("Press enter to exit.")
I posted the following on the python tutor list 3 days ago ... and
haven't heard a peep from anyone - which is highly unusual on that list.
[Apologies for the slightly longer post due to code
with tests cases included at the end .]
====================
I have created a "severely restricted" environment within with
users can learn the basics of programming in Python.
[note: eval, exec, chr, input, raw_input are not allowed.]
Within that environment, I want to have the user test the five
valid forms that an import statement can have, by attempting to
import a fake module whose name is "useful". Other "import"
statements are disallowed.
1. import useful
2. from useful import *
3. from useful import valid_function1 [, valid_function2, ...]
4. from useful import valid_function as better_named_function
5. import useful as not_so_useful_after_all
As far as I can tell, the following works, but it looks rather
"clunky" to me. My *very limited* experience with the
"re" module may have something to do with this.
Any suggestion would be most welcome.
André
=======Here's the code formatted (fingers crossed) to work if cut and
pasted from email =========================
# test_import.py
import re
isolate_words = re.compile(r'\W+') # used with .split()
# pre-compiled some regular expression with allowable use of "import"
imp_use = re.compile('^import useful', re.MULTILINE)
imp_use_as = re.compile('^import useful as (\w+)', re.MULTILINE)
from_use_imp_star = re.compile('^from useful import \*', re.MULTILINE)
from_use_imp_names = re.compile(
"^from useful import (\w+(,[ ]*\w+)*)",
re.MULTILINE)
from_use_imp_as = re.compile(
"^from useful import (\w+) as (\w+)",
re.MULTILINE)
# In the following, "r" is used so that \b identifies a word boundary,
# and is not interpreted as backslash by Python.
import_misuse = re.compile(r'\bimport\b', re.MULTILINE)
# use to commenting out the valid "import" statements after processed.
comment_from = re.compile('^from ', re.MULTILINE)
comment_import = re.compile('^import ', re.MULTILINE)
# Create a fake module which can be "imported"
right = "turn_right():\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" turn_left()\n\n"
around = "turn_around():\n"+\
" turn_left()\n"+\
" turn_left()\n\n"
up_east = "climb_up_east():\n"+\
" turn_left()\n"+\
" move()\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" turn_left()\n\n"
up_west = "climb_up_west():\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" move()\n"+\
" turn_left()\n\n"
down_west = "climb_down_west():\n"+\
" turn_left()\n"+\
" move()\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" turn_left()\n\n"
down_east = "climb_down_east():\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" turn_left()\n"+\
" move()\n"+\
" turn_left()\n\n"
commands = {'turn_right': right, 'turn_around': around,
'climb_up_east': up_east, 'climb_up_west': up_west,
'climb_down_east': down_east, 'climb_down_west': down_west}
#=== end of info on fake module
# The following fonctions are helper functions to
# process the "import" statement:
# they add the appropriate "imported commands"
# before the "import" statement,
# before commenting out (by pre-pending #) the "import" statement line
def import_useful():
added_text = ''
for instruction in commands:
new = "def " + 'useful.' + commands[instruction]
added_text += new
return added_text, True
def from_useful_import_star():
added_text = ''
for instruction in commands:
new = "def " + commands[instruction]
added_text += new
return added_text, True
def import_useful_as(syn):
added_text = ''
for instruction in commands:
new = "def " + syn + '.' + commands[instruction]
added_text += new
return added_text, True
def from_useful_import_names(names):
added_text = ''
for instruction in isolate_words.split(names):
try:
new = "def " + commands[instruction]
except:
print instruction, " not found in module useful"
added_text += new
return added_text, True
def from_useful_import_as(name, syn):
added_text = ''
try:
new = "def " + commands[name].replace(name, syn)
except:
print name, " not found in module useful"
added_text += new
return added_text, True
def process_no_import():
added_text = ''
return added_text, True
# the basic processing function
def process_file(file_text):
if imp_use_as.search(file_text): # look for "import useful as ..."
syn = imp_use_as.findall(file_text)
added_text, safe_import_flag = import_useful_as(syn[0])
file_text = comment_import.sub('#import ', file_text)
elif imp_use.search(file_text): # perhaps the "as ..." part is
# missing
added_text, safe_import_flag = import_useful()
file_text = comment_import.sub('#import ', file_text)
elif from_use_imp_star.search(file_text):
added_text, safe_import_flag = from_useful_import_star()
file_text = comment_from.sub('#from ', file_text)
elif from_use_imp_as.search(file_text):
names = from_use_imp_as.findall(file_text)
name = names[0][0]
syn = names[0][1]
added_text, safe_import_flag = from_useful_import_as(name, syn)
file_text = comment_from.sub('#from ', file_text)
elif from_use_imp_names.search(file_text):
names = from_use_imp_names.findall(file_text)
added_text, safe_import_flag = \
from_useful_import_names(names[0][0])
file_text = comment_from.sub('#from ', file_text)
elif import_misuse.search(file_text):
safe_import_flag = False
file_text = '' # remove it all
added_text = '# import keyword used improperly'
else:
added_text = ''
safe_import_flag = True # nothing found
added_text += file_text
return added_text, safe_import_flag
#======== Various test cases == only self-testing stuff follows
test1 = '''# test1: no import
other instructions'''
test2 = '''# test2
import useful
other instructions'''
test3 = '''# test3
from useful import *
other instructions'''
test4 = '''# test4
from useful import turn_around, turn_right, climb_up_east
other instructions'''
test5 = '''# test5
import useful as use
other instructions'''
test6 = '''# test6
from useful import turn_right
other instructions'''
test7 = '''# test6
from useful import turn_right
other instructions'''
test8 = '''# test8
from useful import turn_right as vire_a_droite
other instructions'''
test9 = '''# test9
import sys
other instructions'''
test10 = '''# test10
from sys import *
other instructions'''
test11 = '''# test11
# import in comment
import useful
other instructions'''
test12 = '''# test12
important test'''
test13 = '''# test 13
import useful
# import sys
other instructions'''
test14 = '''# test14: two import statements; good one first
import useful
import sys
other instructions'''
test15 = '''# test15: two import statements; bad one first
import useful
import sys
other instructions'''
test16 = '''# test16: bad import, indented
import sys
other instructions'''
if __name__ == "__main__":
print "=====begin 1: no import======"
added_text, safe_import_flag = process_file(test1)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 2======"
added_text, safe_import_flag = process_file(test2)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 3======"
added_text, safe_import_flag = process_file(test3)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 4======"
added_text, safe_import_flag = process_file(test4)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 5======"
added_text, safe_import_flag = process_file(test5)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 6======"
added_text, safe_import_flag = process_file(test6)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 7======"
added_text, safe_import_flag = process_file(test7)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 8======"
added_text, safe_import_flag = process_file(test8)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 9: import not allowed======"
added_text, safe_import_flag = process_file(test9)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 10: import not allowed======"
added_text, safe_import_flag = process_file(test10)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 11: import ok in text and import in comment======"
added_text, safe_import_flag = process_file(test11)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 12: word used: important; should be ok ======"
added_text, safe_import_flag = process_file(test12)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 13: 2nd import in comment ======"
added_text, safe_import_flag = process_file(test13)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 14: two import statements; good one first ======"
added_text, safe_import_flag = process_file(test14)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 15: two import statements; bad one first ======"
added_text, safe_import_flag = process_file(test15)
print added_text
print "safe import flag = ", safe_import_flag
print "=====begin 16: bad import, indented ======"
added_text, safe_import_flag = process_file(test16)
print added_text
print "safe import flag = ", safe_import_flag
print "====="
wait = input("Press enter to exit.")