python goto 包，,http://ent

python goto 包，,http://ent

http://entrian.com/goto/

# Example 1: Breaking out from a deeply nested loop:from goto import goto, labelfor i in range(1, 10):    for j in range(1, 20):        for k in range(1, 30):            print i, j, k            if k == 3:                goto .endlabel .endprint "Finished\n"# Example 2: Restarting a loop:from goto import goto, labellabel .startfor i in range(1, 4):    print i    if i == 2:        try:            output = message        except NameError:            print "Oops - forgot to define ‘message‘!  Start again."            message = "Hello world"            goto .startprint output, "\n"# Example 3: Cleaning up after something fails:from goto import goto, label# Imagine that these are real worker functions.def setUp(): print "setUp"def doFirstTask(): print 1; return Truedef doSecondTask(): print 2; return Truedef doThirdTask(): print 3; return False  # This one pretends to fail.def doFourthTask(): print 4; return Truedef cleanUp(): print "cleanUp"# This prints "setUp, 1, 2, 3, cleanUp" - no "4" because doThirdTask fails.def bigFunction1():    setUp()    if not doFirstTask():        goto .cleanup    if not doSecondTask():        goto .cleanup    if not doThirdTask():        goto .cleanup    if not doFourthTask():        goto .cleanup    label .cleanup    cleanUp()bigFunction1()print "bigFunction1 done\n"# Example 4: Using comefrom to let the cleanup code take control itself.from goto import comefrom, labeldef bigFunction2():    setUp()    if not doFirstTask():        label .failed    if not doSecondTask():        label .failed    if not doThirdTask():        label .failed    if not doFourthTask():        label .failed    comefrom .failed    cleanUp()bigFunction2()print "bigFunction2 done\n"# Example 5: Using a computed goto:from goto import goto, labellabel .getinputi = raw_input("Enter either ‘a‘, ‘b‘ or ‘c‘, or any other letter to quit: ")if i in (‘a‘, ‘b‘, ‘c‘):    goto *ielse:    goto .quitlabel .aprint "You typed ‘a‘"goto .getinputlabel .bprint "You typed ‘b‘"goto .getinputlabel .cprint "You typed ‘c‘"goto .getinputlabel .quitprint "Finished\n"# Example 6: What happens when a label is missing:from goto import goto, labellabel .realgoto .unreal      # Raises a MissingLabelError exception.

python goto 包