How can I specify a class method as a callback target in Python?

Question

I'm using the sftp module of paramiko to transfer payloads to remote hosts. Part of the

sftp.put

call allows for specifying a callback method with signature

func(int,int)

. I'm trying to put a transfer stats method into my

Connection

class to keep track of payload progress.

Here's the class I have currently:

class Connection:



    def __init__(self, endpoint, RSAKeyObj):

        self.displayHost = bcolors.OKGREEN + endpoint + bcolors.ENDC

        self.transport = paramiko.Transport((endpoint,4022))

        self.transport.connect(username='transit', pkey=RSAKeyObj)

        self.sftp = paramiko.SFTPClient.from_transport(self.transport)



        try:

            # initial sftp directory setup

            log.info('[{0}]: Setting up remote directories...'.format(self.displayHost))

            log.info(self.sftp.mkdir(JAIL_DIR))

        except:

            pass



    def static_vars(**kwargs):

        def decorate(func):

            for k in kwargs:

                setattr(func, k, kwargs[k])

            return func

        return decorate



    @static_vars(counter=0)

    def TransferStats(self, transferedBytes, totalBytes):

        if (transferedBytes / totalBytes) >= TransferStats.counter:

            log.info('Transferred: {}% [{}/{}]'.format(round((transferedBytes/totalBytes)*100,2), transferedBytes, totalBytes))

            TransferStats.counter += 0.025



    def Transmit(self,targetDir, payloadPath):

        displayText = 'Transferring package {}...'.format(payloadPath)

        self.TransferStats().counter=0



        log.info('[%s] ' % self.displayHost + displayText)

        log.info(self.sftp.put(payloadPath, '%s/%s' % (targetDir,payloadPath), callback=self.TransferStats()))

However when I try this, I get the following error:

ERROR - (, TypeError('TransferStats() takes exactly 3 arguments (1 given)',), )

This makes me think that the callback isn't getting recognized by paramiko when it tries to send it's

(int,int)

because of the

self

declaration. Is there a way around this?

Answer 1

Your problem is in :

    log.info(self.sftp.put(payloadPath, '%s/%s' % (targetDir,payloadPath), callback=self.TransferStats()))

Your error :

ERROR - (, TypeError('TransferStats() takes exactly 3 arguments (1 given)',), )

Is caused by calling TransferStats with no arguments (self.TransferStats() will result in 1 argument : the class (as it is a class method))

Just pass the classmethod:

    log.info(self.sftp.put(payloadPath, '%s/%s' % (targetDir,payloadPath), callback=self.TransferStats))

EDIT : You have the same problem in the following line :

self.TransferStats().counter=0

Remove the parentheses :

self.TransferStats.counter=0

Also, your counter attribute on TransferStats is a hidden a global, resetted at each Transmit call.

How can I specify a class method as a callback target in Python?

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