首先，请为下面非常长的，非常可怕的代码道歉。它正在进行中，我粘贴了所有内容，因为它可能需要运行才能找到问题所在。
我得到错误代码“在赋值之前引用的局部变量'dennisov_type'，我认为这是因为我试图从外层（缩进之外）引用它。但是我试图通过在if语句之前的行上键入“global dennisov_type”来使得要引用的变量（dennisov_type）成为一个全局变量，以及在函数内部之后，在它之外输入“global dennisov_type”，几乎无处不在我可以。但是当我这样做时，我正在获取错误代码“全局名称'dennisov_type'未被定义”，即使它被定义了。
从Tkinter窗口的下拉框中选择一个选项并按下“选择”按钮后，代码出现。
有人会介意在Python编辑器中为我运行这个，并告诉我哪里出错了吗？
from Tkinter import Tk, Button, Canvas, END, Spinbox
from ttk import Progressbar, Combobox
from urllib import urlopen
from re import findall
import re
import itertools
## Create a window
window = Tk()
## Give the window a title
window.title('Watch finder')
## Types of Dennisov watches
dennisov_type_list = ['Barracuda Limited','Barracuda Chronograph',
'Barracuda Mechanical','Speedster','Free Rider',
'Nau Automatic','Lady Flower','Enigma','Number One']
dennisov_file = open('dennisov_url.html', 'w')
dennisov_file.write('''
<!DOCTYPE html>
<html>
<head>
<title>Watches</title>
</head>
<body>
''')
#### Display the quanity of watches available for each type
##quantity_box = len(watch_option)
##
####
##for watch, number in enumerate(watch_option):
## watch_number_name = watch_option[number][0]
## watch_number_image = watch_option[number][1]
## watch_number_price = watch_option[number][2]
## watch_number_link = watch_option[(number)][3]
#### dennisov_file.write('<h1>' + watch_number_name + '</h1>')
## print watch_number_image
#### dennisov_file.write('<img src="' + watch_number_image + '">\n')
## print watch_number_price
#### dennisov_file.write('<h2>' + watch_number_price + '</h2>')
## print watch_number_link
#### dennisov_file.write('<a href="'+watch_number_link+'">'+watch_number_link+'</a>')
##
dennisov_file.write('''
</body>
</html>
''')
## Define function for ...............
def display_choice():
dennisov_type_selection = (dennisov_type_dropdown.get() + '\n')
if dennisov_type_selection == 'Barracuda Limited':
dennisov_type = 'barracuda_chronograph'
elif dennisov_type_selection == 'Barracuda Chronograph':
dennisov_type = 'barracuda_chronograph'
elif dennisov_type_selection == 'Barracuda Mechanical':
dennisov_type = 'barracuda_mechanical'
elif dennisov_type_selection == 'Speedster':
dennisov_type = 'speedster'
elif dennisov_type_selection == 'Free Rider':
dennisov_type = 'free_rider'
elif dennisov_type_selection == 'Nau Automatic':
dennisov_type = 'nau_automatic'
elif dennisov_type_selection == 'Lady Flower':
dennisov_type = 'lady_flower'
elif dennisov_type_selection == 'Enigma':
dennisov_type = 'enigma'
elif dennisov_type_selection == 'Number One':
dennisov_type = 'number_one'
dennisov_url = 'https://denissov.ru/en/'+ dennisov_type + '/'
dennisov_url_subpage = dennisov_url[19:]
## Make the html document just created equal to an opened and read URL????
##???????????????????????????????????????????????????????????????????
dennisov_html = urlopen(dennisov_url).read()
## Replace instances of double quotation marks in the text with singles
## so that the findall regex code does not get confused
dennisov_html = dennisov_html.replace('"', "'")
## Find all of the images of the watches. Each watch image starts with the text
## "img src=". Do not match those with any " symbols in the URL
watch_image_urls = findall("<img src='(/files/collections/o[^']*)'", dennisov_html)
## Add the URL domain to each watch image subpage to create full addresses
watch_image_urls = ['https://denissov.ru' + remainder for remainder in watch_image_urls]
## dennisov_file.write(' <img src="' + image + '">\n')
## Return the watch type. The watch type is in a title tag called "titlusref"
## and can be any combination of letters and spaces, followed by a space and
## "<" symbol.
watch_type = findall("titlusref'\>([a-zA-Z]+ *[a-zA-Z]*) *\<", dennisov_html)[0]
## Find all of the links when each watch is clicked. Each watch link starts
## with the text "a href=" followed by the subpage, followed by any
## letter, number and "_" symbol combination, followed by a backslash
watch_link_urls = findall("a href='" + (dennisov_url_subpage) + "([A-Za-z0-9_]+/)", dennisov_html)
## Add the main URL to each watch subpage
watch_link_urls = [str(dennisov_url) + remainder for remainder in watch_link_urls]
## Find all of the model numbers of each watch. Each model starts with the text
## "covername" then any combination of letters, dots and spaces.
watch_models = findall("covername'>([A-Z a-z0-9\.]+)", dennisov_html)
## Add the watch type to each watch model, seperated by a space, to create the
## full watch names
watch_names = [str(watch_type) + " " + remainder for remainder in watch_models]
## Get current USD to AUD exchange rate using a known currency website
currency_converter_url = 'http://www.xe.com/currencyconverter/convert/?From=USD&To=AUD'
currency_html = urlopen(currency_converter_url).read()
## Replace instances of double quotation marks in the text with singles
## so that the findall regex code does not get confused
currency_html = currency_html.replace('"', "'")
## Find the exchange rate. The exchange rate starts with "uccResultAmount'>"
## and is then followed by any combination of numbers with a decimal place
exchange_rate = float(findall("uccResultAmount'\>([0-9]+\.[0-9]*)", currency_html)[0])
## Find the price of the models and make into floats. Each model price contains
## numbers followed by the text "USD"
USD_watch_price = [float(price) for price in (findall("([0-9]*) usd", dennisov_html))]
## Convert the USD watch prices to current AUD prices and round to 2 decimals
watch_price = [round(exchange_rate*price, 2) for price in USD_watch_price]
## Add the currency to the prices
watch_price = ["AU $" + str(price) for price in watch_price]
## Match each watch name to its image and URL inside a tuple and place each
## tuple inside a list
watch_list = zip(watch_names, watch_image_urls, watch_price, watch_link_urls)
## For each watch tuple (matching image, name and URL), assign a watch number
watch_option = {'watch_{}'.format(i): e for i, e in enumerate(watch_list)}
## Create a spinbox
spinbox_list = []
spinbox_grid_list = []
for watch, number in enumerate(watch_names):
spinbox = 'spinbox_' + str(watch) + ' = Spinbox(window, width = 5, from_=0, to=10)'
spinbox_grid = 'spinbox_' + str(watch) + '.grid(padx = 2, pady = 2, row = ' + str(1+ 4*watch) +', column = 0)'
spinbox_list.append(spinbox)
spinbox_grid_list.append(spinbox_grid)
spinbox_option = {'spinbox_{}'.format(i):e for i, e in enumerate(spinbox_list)}
spinbox_option_string = '\n'.join(spinbox_option.values())
spinbox_grid_option = {'spinbox_grid_{}'.format(i):e for i, e in enumerate(spinbox_grid_list)}
spinbox_grid_option_string = '\n'.join(spinbox_grid_option.values())
exec(spinbox_option_string)
exec(spinbox_grid_option_string)
## Create the dropdown box for the Dennisov watch types
dennisov_type_dropdown = Combobox(window, width = 25,
values = dennisov_type_list)
## Create the Dennisov model selection canvas
dennisov_model_selection = Canvas(window, width = 400, height = 500,
bg = 'white')
## Create Dennisov type selection button
dennisov_select_button = Button(window, text = 'Select',
command = display_choice)
## Locate elements on grid
dennisov_type_dropdown.grid(pady = 2, padx = 2, row = 0, column = 1)
dennisov_model_selection.grid(padx = 2, pady = 2, row = 1,
column = 0, rowspan = 15, columnspan = 3)
dennisov_select_button.grid(pady = 2, padx = 2, row = 0, column = 2)
dennisov_file.close()
window.mainloop()
答案 0 :(得分：2)
您的dennisov_type_selection == ...条件都不会评估为True。 dennisov_type_selection始终以换行符结尾，并且没有任何字符串与新行进行比较。
由于没有条件执行，因此dennisov_type没有分配任何内容，因此dennisov_url = 'https://denissov.ru/en/'+ dennisov_type + '/'失败并显示"local variable 'dennisov_type' referenced before assignment
尝试将作业更改为
dennisov_type_selection = dennisov_type_dropdown.get()
您还应该在if-elif块中添加else子句，以处理用户输入您不期望的内容时发生的情况。要么使用有用的消息崩溃，要么提前从函数返回，或者指定某种回退值。
elif dennisov_type_selection == 'Number One':
dennisov_type = 'number_one'
else:
raise Exception("Did not recognize selection: {}".format(repr(dennisov_type_selection)))
或者
elif dennisov_type_selection == 'Number One':
dennisov_type = 'number_one'
else:
return
或者
elif dennisov_type_selection == 'Number One':
dennisov_type = 'number_one'
else:
dennisov_type = 'unknown'