我在嘗試從檔案 b.py 中的函式訪問檔案 a.py 中的變數時遇到問題。我試著環顧互聯網，但找不到任何東西，或者我不知道如何尋找我需要的東西。我還嘗試創建另一個檔案并更新檔案 c.py 中的變數，但檔案 b.py 仍然看到變數的第一次初始化。我嘗試更新檔案 a.py 中的變數，然后在 b.py 的函式中匯入 a.py。
檔案 a.py
var = []
def run():
a.welcome()
while True:
menu = a.menu()
if menu == 1:
def retrieve_path(source_path):
"""The function takes 1 parameter and checks if the file name exist as well as the file path
Adds the csv data to a variable
source_path (str): Path against whom to check for validity
"""
if not source_path:
print("Invalid file name, Please try again\n")
return
else:
import os
isFile = os.path.isfile(source_path)
if not isFile:
print("Invalid file path\n")
return
else:
with open(source_path, "r") as csv_file:
csv_reader = csv.reader(csv_file, delimiter=',')
for line in csv_reader:
line = list(line)
var.append(line)
if __name__ == "__main__":
run()
檔案 b.py
我試過這樣，但我得到了變數的第一次初始化 var = []
我首先從檔案 a.py 更新了 var，然后，我嘗試在檔案 b.py 中使用下面的函式，但結果仍然相同。
from a import var
from a import *
import a
def a_function():
from a import var
from a import *
import a
print(var)
print(a.var)
這將列印 var which = [] 的第一次初始化，而不是在附加之后。
如果我從 a 列印 var，它會從函式內部列印它更新。
If I print var from a, from outside the function it prints it updated.
What I don’t understand is, why after updating it, and importing it into b, I still get the first initialization. Debugger didn’t help as well. I can work around it by adding the function retrieve_path inside b.py and then appending the data in another variable inside file b.py but I would like to know why its not importing var updated with the data.
File b.py
var2 = []
def retrieve_path(source_path):
"""The function takes 1 parameter and checks if the file name exist as well as the file path
Adds the csv data to a variable
source_path (str): Path against whom to check for validity
"""
if not source_path:
print("Invalid file name, Please try again\n")
return
else:
import os
isFile = os.path.isfile(source_path)
if not isFile:
print("Invalid file path\n")
return
else:
with open(source_path, "r") as csv_file:
csv_reader = csv.reader(csv_file, delimiter=',')
for line in csv_reader:
line = list(line)
var.append(line)
var2.append(line)
The reason I didn't use Class if that was one of the solutions, is because I haven't learned that much about Classes and don't know how to use them properly for the time being.
I hope I was quite explicit and you understand my dilemma. Also, have in mind I just started learning Python, so a newbi explanation and solution are more than welcomed.
uj5u.com熱心網友回復：
正確的方法是run在訪問之前呼叫函式var。任何一個
import a
a.run
print(a.var)
或者：
from a import var, run
run
print(var)
該import陳述句只運行模塊的內容，而不是其中宣告的函式。
運行腳本的慣用方式確實是你在 a.py 中所擁有的：
if __name__ == "__main__":
run()
run如果您像使用 腳本一樣使用該檔案，則會呼叫該函式python a.py，因為由解釋器直接啟動的檔案將被命名為__main__. 但是匯入的時候是按照檔案名來命名的。所以在這里它會a和不會main。換句話說，run在a.py匯入時永遠不會呼叫。
一種可能性是通過無條件呼叫來結束 a.py run：
...
line = list(line)
var.append(line)
run()
它應該是無害的，因為 Python 會跟蹤已經匯入的模塊，run即使模塊是從多個地方匯入的，也應該只呼叫一次。然而，這將是一種反模式，因為按照慣例import 應該有盡可能少的副作用，而 run 似乎做了很多動作。
uj5u.com熱心網友回復：
好的，這只是我完成的學校專案的一部分，但我想讓這部分的唱片與我為年級所做的有點不同。如果某些功能沒有意義，那是因為專案還沒有完成。我唯一關心的是記錄變數。
主檔案
import tui, csv
records = []
def run():
tui.welcome()
while True:
menu = tui.menu()
if menu == 1:
def retrieve_path(source_path):
"""The function takes 1 parameter and checks if the file name exist as well as the file path
Adds the csv data to a variable
source_path (str): Path against whom to check for validity
"""
if not source_path:
print("Invalid file name, Please try again\n")
return
else:
import os
isFile = os.path.isfile(source_path)
if not isFile:
print("Invalid file path\n")
return
else:
with open(source_path, "r") as csv_file:
csv_reader = csv.reader(csv_file, delimiter=',')
for line in csv_reader:
line = list(line)
records.append(line)
tui.started("Data Loading")
retrieve_path(tui.source_data_path())
tui.completed("Data Loading")
if menu == 2:
tui.started("Retrieving data")
process_menu = tui.process_type()
tui.completed("Retrieving data")
if process_menu == 1:
tui.started("Retrieving entity name")
tui.entity_name()
tui.completed("Retrieving entity name")
if process_menu == 2:
tui.started("Retrieving entity details")
entity, cols = tui.entity_details()
tui.list_entity(entity, cols)
tui.completed("Retrieving entity details")
if menu == 3:
print(tui.main_records)
if menu == 4:
break
if __name__ == "__main__":
run()
第二個檔案是：
tui.py
def welcome():
message = "System Management"
print("*" * len(message))
print(message)
print("*" * len(message))
def menu():
main_menu = "-"
while main_menu != "0":
if main_menu == "-":
print('Main Menu:'
'\n1. Load Data'
'\n2. Process Data'
'\n3. Visualise Data'
'\n4. Save Data'
'\n0. Exit')
elif main_menu in "1234":
return int(main_menu)
elif main_menu not in "1234":
error(main_menu)
return None
else:
print('Main Menu:'
'\n1. Load Data'
'\n2. Process Data'
'\n3. Visualise Data'
'\n4. Save Data'
'\n0. Exit')
main_menu = input()
def started(operation):
print("{} has started.\n".format(operation))
def completed(operation):
print("{} has completed.\n".format(operation))
def error(error_msg):
print("Error! {} is not a valid option.".format(error_msg))
def source_data_path():
print("Please enter the path to the source data file:")
source_path = input()
if ".csv" not in source_path:
return None
else:
return source_path
def process_type():
process_menu = "-"
while process_menu != "0":
if process_menu == "-":
print('Process Menu:'
'\n1. Retrieve entity'
'\n2. Retrieve entity details'
'\n3. Categorise entities by type'
'\n4. Categorise entities by gravity'
'\n5. Summarise entities by orbit'
'\n6. Return to Main Menu')
elif process_menu == "6":
menu()
return None
elif process_menu in "12345":
return int(process_menu)
elif process_menu not in "12345":
error(process_menu)
return None
else:
print('Process Menu:'
'\n1. Retrieve entity'
'\n2. Retrieve entity details'
'\n3. Categorise entities by type'
'\n4. Categorise entities by gravity'
'\n5. Summarise entities by orbit'
'\n6. Return to Main Menu')
process_menu = input()
def entity_name():
entity = input("Please enter the name of an entity: ")
return entity
def entity_details():
entity = input("Please enter the name of an entity: ")
indexes = input("Please enter the indexes number (e.g. 0,1,5,7):\n")
return entity, list(indexes)
第一次做這個專案時，我將 defretrieve_path(source_path): 添加到 tui.py 并且它運行良好。
我真正不明白的是為什么要附加變數記錄，我可以從運行內部和運行函式外部列印它，但在 tui.py 中我只得到記錄 = [] 以及如何在不創建tui.py 中的函式retrieve_path
這是當時對我們的要求，這樣做不是我個人的選擇。
我很抱歉沒有在此處粘貼所有內容并錯誤輸入 == _ main _ 之類的部分。
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標籤：python function file variables