十六、complie方法
1、定义:
compile(...) compile(source, filename, mode[, flags[, dont_inherit]]) -> code object Compile the source string (a Python module, statement or expression) into a code object that can be executed by the exec statement or eval(). The filename will be used for run-time error messages. The mode must be 'exec' to compile a module, 'single' to compile a single (interactive) statement, or 'eval' to compile an expression. The flags argument, if present, controls which future statements influence the compilation of the code. The dont_inherit argument, if non-zero, stops the compilation inheriting the effects of any future statements in effect in the code calling compile; if absent or zero these statements do influence the compilation, in addition to any features explicitly specified.
2、解释:将source编译为代码或者AST对象。代码对象能够通过exec语句来执行或者eval()进行求值。
3、举例:
例1: >>> code = "for i in range(0, 10): print i" >>> cmpcode = compile(code, '', 'exec') >>> exec cmpcode 0 1 2 3 4 5 6 7 8 9 >>> str = "3 * 4 + 5" >>> a = compile(str,'','eval') >>> eval(a) 17 例2: test.cfg内容如下: SQLALCHEMY_POOL_RECYCLE = 10 SQLALCHEMY_ECHO = False filename = 'test.cfg' _dict = {} with open(filename) as config_file: code_obj = compile(config_file.read(), '', 'exec') exec(code_obj, _dict) print _dict.get('SQLALCHEMY_POOL_RECYCLE') print _dict.get('SQLALCHEMY_ECHO') 输出: 10 False 因此_dict 变量获得了test.cfg文件中的配置信息
十七、complex类
1、定义:
class complex(object) | complex(real[, imag]) -> complex number | | Create a complex number from a real part and an optional imaginary part. | This is equivalent to (real + imag*1j) where imag defaults to 0.
2、解释:生成一个复数
3、举例:
>>> complex(1,5) (1+5j) >>> complex(1) (1+0j) >>> complex(1,-5) (1-5j)
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