如何修复 StringVar.get() 问题

Question

I am trying to make autocomplete GUI (like Google's) in Tkinter using StringVar. I defined a callback function, where i used StringVar.get(), where I for different input in Entry I get different output via autocomplete suggestions in ListBox. The problem is that after typing one letter in Entry I get right output but after typing 2 or more I get empty ListBox. Here's the code.

num=input()
num=int(num)
sv=StringVar()
def callback(sv,list,num):
    a=sv.get()
    pom_list = list
    bin_list = []
    lexicographic_sort(pom_list)
    x = binary_search(a, pom_list)
    while x != -1:
        bin_list.append(x)
        pom_list.remove(x)
        x = binary_search(a, pom_list)

    i = 0
    l = Listbox(root, width=70)
    l.grid(row=2, column=5)
    if len(bin_list) == 0 or len(a) == 0:
        l.delete(0, END)

    else:
        for list1 in bin_list:
            if i == num:
                break
            l.insert(END, list1[0])
            i += 1
sv.trace("w", lambda name, index, mode, sv=sv: callback(sv,list,num))
te = Entry(root, textvariable=sv)
te.grid(row=1,column=5)

where list outside callback function is a list of all suggestions, and bin_list is a list of suggestions of StringVar.get() using binary_search.

Answer 1

It is because all matched items for the first letter have been removed from the search list. You should use a cloned search list in callback() . Also don't create new list to show the result list, create the result list once and update its content in callback() . Furthermore, sort the search list beforehand:

def callback(sv, wordlist, num):
    result.delete(0, END) # remove previous result
    a = sv.get().strip()
    if a:
        pom_list = wordlist[:]  # copy of search list
        #lexicographic_sort(pom_list)  # should sort the list beforehand
        x = binary_search(a, pom_list)
        while x != -1 and num > 0:
            result.insert(END, x)
            pom_list.remove(x)
            num -= 1
            x = binary_search(a, pom_list)

...

lexicographic_sort(wordlist)
sv = StringVar()
sv.trace("w", lambda *args, sv=sv: callback(sv, wordlist, num))

...

result = Listbox(root, width=70)
result.grid(row=2, column=5)