2015/10/9 Python基础(21)：可调用和可执行对象

>>> dir(type)
[‘__abstractmethods__‘, ‘__base__‘, ‘__bases__‘, ‘__basicsize__‘, ‘__call__‘, ‘__class__‘, ‘__delattr__‘, ‘__dict__‘, ‘__dictoffset__‘, ‘__doc__‘, ‘__eq__‘, ‘__flags__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, ‘__gt__‘, ‘__hash__‘, ‘__init__‘, ‘__instancecheck__‘, ‘__itemsize__‘, ‘__le__‘, ‘__lt__‘, ‘__module__‘, ‘__mro__‘, ‘__name__‘, ‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subclasscheck__‘, ‘__subclasses__‘, ‘__subclasshook__‘, ‘__weakrefoffset__‘, ‘mro‘]

>>> type(dir)
<type ‘builtin_function_or_method‘>

>>> def foo():pass

>>> type(foo)
<type ‘function‘>

>>> lambdaFunc = lambda x: x * 2
>>> lambdaFunc(12)
24
>>> type(lambdaFunc)
<type ‘function‘>
>>> lambdaFunc.__name__
‘<lambda>‘

>>> def foo():pass

>>> foo.__name__
‘foo‘

>>> type([].append)
<type ‘builtin_function_or_method‘>

>>> eval_code = compile(‘10-2‘,‘‘,‘eval‘)
>>> eval(eval_code)
8

>>> single_code = compile(‘print "Hello world"‘,‘‘,‘single‘)
>>> single_code
<code object <module> at 024DC698, file "", line 1>
>>> exec single_code
Hello world

>>> exec_code = compile("""
req = input(‘Count how many numbers?‘)
for eachNum in range(req):
　　print eachNum
""",‘‘,‘exec‘)
>>> exec exec_code
Count how many numbers?6
0
1
2
3
4
5

>>> eval(‘123‘)
123
>>> int(‘123‘)
123
>>> eval(‘123+234‘)
357
>>> int(‘123+234‘)

Traceback (most recent call last):
File "<pyshell#10>", line 1, in <module>
int(‘123+234‘)
ValueError: invalid literal for int() with base 10: ‘123+234‘

exec obj

>>> exec """
x = 0
print ‘x is currently:‘,x
while x < 5:
　　x += 1
　　print ‘incrementing x to:‘,x
"""
x is currently: 0
incrementing x to: 1
incrementing x to: 2
incrementing x to: 3
incrementing x to: 4
incrementing x to: 5

>>> f = open(‘xcount.py‘) # open the file
>>> exec f # execute the file
x is currently: 0
incrementing x to: 1
incrementing x to: 2
incrementing x to: 3
incrementing x to: 4
incrementing x to: 5

>>> exec f
>>>

>>> f.tell()
116
>>> f.close()
>>> from os.path import getsize
>>> getsize(‘xcount.py‘)
116

>>> f.seek(0)
>>> exec f
x is currently: 0
incrementing x to: 1
incrementing x to: 2
incrementing x to: 3
incrementing x to: 4
incrementing x to: 5
>>> f.close()

dashes = ‘\n‘ + ‘-‘ * 50
exec_dict = {
‘f‘:‘‘‘               #for loop
for %s in %s:
    print %s
‘‘‘,

‘s‘:‘‘‘               # sequence while loop
%s = 0
%s = %s
while %s < len(%s):
    print %s[%s]
    %s = %s + 1
‘‘‘,

‘n‘:‘‘‘                # counting while loop
%s = %d
while %s < %d:
    print %s
    %s = %s + %d
‘‘‘
}

def main():

    ltype = raw_input(‘Loop type? (For/While)‘)
    dtype = raw_input(‘Data type? (Number/Sequence)‘)

    if dtype == ‘n‘:
        start = input(‘Starting value? ‘)
        stop = input(‘Ending value (non-inclusive)? ‘)
        step = input(‘Stepping value? ‘)
        seq = str(range(start, stop, step))

    else:
        seq = raw_input(‘Enter sequence:‘)

    var = raw_input(‘Iterative variable name?‘)

    if ltype == ‘f‘:
        exec_str = exec_dict[‘f‘] % (var, seq, var)

    elif ltype == ‘w‘:
        if dtype == ‘s‘:
            svar = raw_input(‘Enter sequence name? ‘)
            exec_str = exec_dict[‘s‘] %                        (var, svar, seq, var, svar, svar, var, var, var)
        elif dtype == ‘n‘:
            exec_str = exec_dict[‘n‘] %                        (var, start, var, stop, var, var, var, step)

    print dashes
    print ‘The custom-generated code for you is:‘ + dashes
    print exec_str + dashes
    print ‘The execution of the code:‘ + dashes
    exec exec_str
    print dashes

if __name__ == ‘__main__‘:
    main()

    

def foo():
    return True

def bar():
    ‘bar() does not do much‘
    return True

foo.__doc__ = ‘foo() does not do much‘
foo.tester = ‘‘‘
if foo():
    print ‘PASSED‘
else:
    print ‘FAILED‘
‘‘‘

for eachAttr in dir():
    obj = eval(eachAttr)
    if isinstance(obj, type(foo)):
        if hasattr(obj, ‘__doc__‘):
            print ‘\nFunction "%s" has a doc string:\n\t%s‘                  % (eachAttr, obj.__doc__)
        if hasattr(obj, ‘tester‘):
            print ‘Function "%s" has a tester... executing‘                  % eachAttr
            exec obj.tester
        else:
            print ‘Function "%s" has no tester... skipping‘                  % eachAttr
    else:
        print ‘"%s" is not a function‘ % eachAttr

>>> 
"__builtins__" is not a function
"__doc__" is not a function
"__file__" is not a function
"__name__" is not a function
"__package__" is not a function

Function "bar" has a doc string:
bar() does not do much
Function "bar" has no tester... skipping

Function "foo" has a doc string:
foo() does not do much
Function "foo" has a tester... executing
PASSED