Python - 未引发异常

Question

我正在尝试编写一个小脚本来检查作为命令行参数传递的文件是否带有正确的括号。

我创建了一个异常来处理函数停止点，但似乎无法正确引发它。

当我在Python解释器中测试代码时，它似乎可以工作(即它识别出它应该引发异常，但是当我使用我拥有的示例文件(括号错误)测试我的文件时，它仍然打印表明已成功检查

你有什么想法吗？

最好，

代码:

import sys
from stack import *


class BracketException(Exception) :
    """
    Exception qui gère les problèmes de parenthesage : mauvaise parenthèse,
    mauvais placement etc...
    """

    def __init__(self, char, lineNumber, charNumber) :
        self.char = char
        self.lineNumber = lineNumber
        self.charNumber = charNumber

    def __str__(self) :
        return(self.char + " at line " + str(self.lineNumber) + " char " + str(self.charNumber))


def checker(file) :
    lineNumber = 1
    charNumber = 1

    stacked = Stack()
    openers = ["(", "[", "{"]
    closers = [")", "]", "}"]

    inChannel = open(file, "r")

    for line in file :
        for char in line :
            if char in openers :
                stacked.push([char, lineNumber, charNumber])
                print(stacked.top())
            elif char in closers :
                try :
                    if openers[closers.index(char)] == stacked.top()[0] :
                        stacked.pop()
                    else :
                        raise BracketException(char, lineNumber, charNumber)
                except StackEmptyError :
                    raise BracketException(char, lineNumber, charNumber)

            charNumber += 1
        charNumber = 1
        lineNumber += 1

    inChannel.close()

    if not stacked.is_empty() :
        raise BracketException(stacked.top()[i] for i in range(3))

def __main__() :

    try :
        fichier = sys.argv[1]
        checker(fichier)
        print("it's checked !")
    except BracketException as ex :
        print(ex)
    except IndexError :
        print("Wrong number of parameters")
    except Exception as e :
        print(e)

if __name__ == "__main__" :
    __main__()

Answer 1

您正在迭代给定的文件名，而不是创建的文件句柄。文件名中可能没有不平衡的括号，因此也不异常(exception)。

def checker(file) :
    lineNumber = 1
    charNumber = 1

    stacked = Stack()
    openers = ["(", "[", "{"]
    closers = [")", "]", "}"]

    inChannel = open(file, "r")  # file handle is inChannel

    for line in file :  #  iterating over file name, not file handle

您应该切换到

with open(file, "r") as inChannel:
    for line in inChannel :

即使抛出异常，也要确保关闭文件 - 这是文件处理的首选方式，请参阅 docs.python.org - reading and writing files

<小时/>

我无法测试这个(没有堆栈模块 - 如果需要，我使用列表)，但这应该更快:

def checker(filename) :
    lineNumber = 1
    charNumber = 1

    stacked = Stack()

    openers = set( "{[(")  # sets are better suited for test of "in"
    closers = set( "}])")  # same

    # mapping between closing bracket at hand and what should be on the stack
    # also faster then .index()ing into a list
    open_for_close = { ")":"(","}":"{","]":"[" }

    with open(filename, "r") as f:
        for line in f:            # iterate over the filehandle 
            for char in line:
                if char in openers:
                    stacked.push([char, lineNumber, charNumber])
                    print(stacked.top())
                elif char in closers:
                    try :
                        if open_for_close[char] == stacked.top()[0] :
                            stacked.pop()
                        else :
                            raise BracketException(char, lineNumber, charNumber)
                    except StackEmptyError :
                        raise BracketException(char, lineNumber, charNumber)
                charNumber += 1
            charNumber = 1
            lineNumber += 1

    if not stacked.is_empty() :
        raise BracketException(stacked.top()[i] for i in range(3))