Pass argument to callback?

Question

I'm working on my first python script. I want to use a variable within a callback-function:

def run(self, edit):
    gitFolder = os.path.basename(gitRoot)
    #Get branch
    self.run_command(['git', 'rev-parse','--abbrev-ref','HEAD'], self.branchDone)


def branchDone(self, result):
    build =  "./Build-Release.ps1 " + gitFolder + " " + result +" -Deploy;"
    print build

How do I make gitFolder available to the method branchDone?

return gitFolder - after `self.run_command(...)` in your `run(...)` function definition. try that. Also, you can add gitFolder as an argument in your `branchDone(self,result,gitFolder)` where you can pass it in. Otherwise, just declare gitFolder globally, and use it in both functions. — ha9u63a7, Nov 12 '14 at 08:31
nope, File ".\Panagora.py", line 40, in branchDone NameError: global name 'gitFolder' is not defined — Himmators, Nov 12 '14 at 08:33
I would guess it's because the return has not executed when branchDone is run. — Himmators, Nov 12 '14 at 08:35
possible duplicate of [Using global variables in a function other than the one that created them](http://stackoverflow.com/questions/423379/using-global-variables-in-a-function-other-than-the-one-that-created-them) — ha9u63a7, Nov 12 '14 at 08:36

Vishnu Upadhyay · Accepted Answer · 2014-11-12T08:44:00.907

2

simply return gitFolder from run and call run in branchcode Try this:-

def run(self, edit):
    gitFolder = os.path.basename(gitRoot)
    #Get branch
    self.run_command(['git', 'rev-parse','--abbrev-ref','HEAD'], self.branchDone)
    return gitFolder

def branchDone(self, result):
    build =  "./Build-Release.ps1 " + run() + " " + result +" -Deploy;" #run() returns gitfolders
    print build

There is another way

   def run(self, edit):
        self.gitFolder = os.path.basename(gitRoot)
        #Get branch
        self.run_command(['git', 'rev-parse','--abbrev-ref','HEAD'], self.branchDone)


    def branchDone(self, result):
        build =  "./Build-Release.ps1 " + self.gitFolder + " " + result +" -Deploy;"

But it carries a problem that you need to execute the run function before executing branchcode, else self.gitfolder will be undefined and raise Attribute error.

edited Nov 12 '14 at 08:44

answered Nov 12 '14 at 08:35

Vishnu Upadhyay

5,043
1
13
24

1

I think that needs to be self.run(), but apart from that, great! – Himmators Nov 12 '14 at 08:37
@KristofferNolgren i think i gave answer of your question, check the updated code. – Vishnu Upadhyay Nov 12 '14 at 08:44
Yes, this is great I just needed to wait before I could confirm! – Himmators Nov 12 '14 at 08:47

Devesh Saini · Answer 2 · 2014-11-12T08:47:46.303

1

As I am observing, these are class methods, you can define a class attribute to share gitFolder across them.

def run(self, edit):
    self.gitFolder = os.path.basename(gitRoot)
    #Get branch
    self.run_command(['git', 'rev-parse','--abbrev-ref','HEAD'], self.branchDone)


def branchDone(self, result):
    build =  "./Build-Release.ps1 " + self.gitFolder + " " + result +" -Deploy;"
    print build

edited Nov 12 '14 at 08:47

answered Nov 12 '14 at 08:39

Devesh Saini

557
5
16

1

these are class methods, no reason to use global. – jwillis0720 Nov 12 '14 at 08:43

score 1 · Answer 3 · answered Nov 12 '14 at 08:40

One way would be using functools.partial:

def run(self, edit):
    gitFolder = os.path.basename(gitRoot)
    #Get branch
    callback = functools.partial(self.branchDone, gitFolder)
    self.run_command(['git', 'rev-parse','--abbrev-ref','HEAD'], callback)

def branchDone(self, gitFolder, result):
    build =  "./Build-Release.ps1 " + gitFolder + " " + result +" -Deploy;"
    print build

score 1 · Answer 4 · answered Nov 12 '14 at 08:57

If you don't need branchDone except for as a callback, consider defining it as a closure inside run:

from subprocess import check_output

def run_command(command, callback):
    callback(check_output(command).strip())

class Foo(object):
    def run(self, edit):
        gitFolder = "some_magic"
        def branch_done(result):
            print "./Build-Release.ps1 " + gitFolder + " " + result + " -Deploy;"
        run_command(['git', 'rev-parse','--abbrev-ref','HEAD'], branch_done)

Foo().run("edit")

Pass argument to callback?

4 Answers4