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Repeat iteration in a loop if an error occurs

Is there a command, for example, breakand continuethat can repeat the recent iteration?

For example, when an exception is thrown.

for i in range(0,500):
    try:
        conn = getConnection(url+str(i))
        doSomething(conn)
    except:
        repeat

Let there be an iteration, where is the ivalue of the variable 6. A connection error occurred during this iteration. I want to repeat this iteration.

Is there a team that can do this?

Of course I can do this:

i=0
while i!=500:
    try:
        conn = getConnection(url+str(i))
        doSomething(conn)
        i+=1
    except:
        pass
+10
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5 answers

No, there is no command to “rewind” a for loop in Python.

You can use a loop while True:inside a for loop:

for i in range(500):
    while True:
        try:
            conn = getConnection(url+str(i))
            doSomething(conn)
        except Exception: # Replace Exception with something more specific.
            continue
        else:
            break

or without else::

for i in range(500):
    while True:
        try:
            conn = getConnection(url+str(i))
            doSomething(conn)
            break
        except Exception: # Replace Exception with something more specific.
            continue

, , .

+9

:

def process_connections(n_connections, url, max_tries=50):
    i = 0
    try_count = 0
    while i < n_connections:
        try:
            conn = getConnection(url+str(i))
            yield conn
        except:
            try_count += 1
            if try_count > max_tries:
                raise Exception("Unable to connect after %s tries" % max_tries)
        else:
            i += 1 # increments only if no exception

:

for conn in process_connections(500, url):
    do_something(conn)
+2
for i in range(500):
    while True
        try:
            conn = getConnection(url+str(i))
            break
        except Exception: # still allows to quit with KeyboardInterrupt
            continue
    do_your_stuff()

, while.

, :

def keep_trying(fn, *args, **kwargs):
    def inner(*args, **kwargs):
        while True:
            try:
                return fn(*args, **kwargs)
            except Exception:
                continue
    return inner

# later you can use it simple like this:
for i in range(500):
    conn = keep_trying(getConnection)(url+str(i))
+2

if?

n=6
i=0
while i!=500:
    failed = False;
    try:
        conn = getConnection(url+str(i))
        doSomething(conn)
        i+=1
    except:
        #handle error
        failed = True;

    #try again if n-th case failed first time
    if(i == n and failed):
        try:
            conn = getConnection(url+str(i))
            doSomething(conn)
        except:
            #handle error
0

, . sam @PierreAlex, .

for i in range(500):
    for retry in range(10):
        try:
            conn = getConnection(url+str(i))
            doSomething(conn)
        except Exception: # Replace Exception with something more specific.
            time.sleep(1)
    else:
        print "iteration", i, "failed"
0

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