Re: [PATCH] make hg-to-git compatible with python2.x and 3.x

[Junio C Hamano <gitster@pobox.com>]

Hervé Beraud <herveberaud.pro@gmail.com> writes:

> Signed-off-by: Hervé Beraud <herveberaud.pro@gmail.com>
> ---
>  contrib/hg-to-git/hg-to-git.py | 52 +++++++++++++++++++++---------------------
>  1 file changed, 26 insertions(+), 26 deletions(-)

I think you shrunk the scope of the change, but I feel that it is
still a bit under-explained.  Let me try to write a proposed commit
log message and ask you to see if I understood the idea behind the
changes correctly:

    Rewrite features that are no longer supported (or recommended)
    in Python 3 in the script so that it can be used with both
    Python 2 and 3, namely:

    - print is not a statement; use print() function instead.
    - dict.has_key(key) is no more; use "key in dict" instead.
    - map(lambda ..., collection) is not liked; use list comprehension.

Hopefully this would also serve as an illustration of the kind of
things we want in our log message.

I am not sure about the change from map(lambda ...) to list
comprehension, though.  Not that I have a preference for or against
(I am not a Python person), but I do not know if this is a change
necessary to run with Python 3 or if it is merely more preferred to
use list comprehension.

Thanks.

> diff --git a/contrib/hg-to-git/hg-to-git.py b/contrib/hg-to-git/hg-to-git.py
> index de3f81667ed97..8fa7698df5c20 100755
> --- a/contrib/hg-to-git/hg-to-git.py
> +++ b/contrib/hg-to-git/hg-to-git.py
> @@ -42,7 +42,7 @@
>  
>  def usage():
>  
> -        print """\
> +        print("""\
>  %s: [OPTIONS] <hgprj>
>  
>  options:
> @@ -54,7 +54,7 @@ def usage():
>  
>  required:
>      hgprj:  name of the HG project to import (directory)
> -""" % sys.argv[0]
> +""" % sys.argv[0])
>  
>  #------------------------------------------------------------------------------
>  
> @@ -104,29 +104,29 @@ def getgitenv(user, date):
>  if state:
>      if os.path.exists(state):
>          if verbose:
> -            print 'State does exist, reading'
> +            print('State does exist, reading')
>          f = open(state, 'r')
>          hgvers = pickle.load(f)
>      else:
> -        print 'State does not exist, first run'
> +        print('State does not exist, first run')
>  
>  sock = os.popen('hg tip --template "{rev}"')
>  tip = sock.read()
>  if sock.close():
>      sys.exit(1)
>  if verbose:
> -    print 'tip is', tip
> +    print('tip is', tip)
>  
>  # Calculate the branches
>  if verbose:
> -    print 'analysing the branches...'
> +    print('analysing the branches...')
>  hgchildren["0"] = ()
>  hgparents["0"] = (None, None)
>  hgbranch["0"] = "master"
>  for cset in range(1, int(tip) + 1):
>      hgchildren[str(cset)] = ()
>      prnts = os.popen('hg log -r %d --template "{parents}"' % cset).read().strip().split(' ')
> -    prnts = map(lambda x: x[:x.find(':')], prnts)
> +    prnts = [x[:x.find(':')] for x in prnts]
>      if prnts[0] != '':
>          parent = prnts[0].strip()
>      else:
> @@ -154,15 +154,15 @@ def getgitenv(user, date):
>          else:
>              hgbranch[str(cset)] = "branch-" + str(cset)
>  
> -if not hgvers.has_key("0"):
> -    print 'creating repository'
> +if "0" not in hgvers:
> +    print('creating repository')
>      os.system('git init')
>  
>  # loop through every hg changeset
>  for cset in range(int(tip) + 1):
>  
>      # incremental, already seen
> -    if hgvers.has_key(str(cset)):
> +    if str(cset) in hgvers:
>          continue
>      hgnewcsets += 1
>  
> @@ -180,27 +180,27 @@ def getgitenv(user, date):
>      os.write(fdcomment, csetcomment)
>      os.close(fdcomment)
>  
> -    print '-----------------------------------------'
> -    print 'cset:', cset
> -    print 'branch:', hgbranch[str(cset)]
> -    print 'user:', user
> -    print 'date:', date
> -    print 'comment:', csetcomment
> +    print('-----------------------------------------')
> +    print('cset:', cset)
> +    print('branch:', hgbranch[str(cset)])
> +    print('user:', user)
> +    print('date:', date)
> +    print('comment:', csetcomment)
>      if parent:
> -	print 'parent:', parent
> +	print('parent:', parent)
>      if mparent:
> -        print 'mparent:', mparent
> +        print('mparent:', mparent)
>      if tag:
> -        print 'tag:', tag
> -    print '-----------------------------------------'
> +        print('tag:', tag)
> +    print('-----------------------------------------')
>  
>      # checkout the parent if necessary
>      if cset != 0:
>          if hgbranch[str(cset)] == "branch-" + str(cset):
> -            print 'creating new branch', hgbranch[str(cset)]
> +            print('creating new branch', hgbranch[str(cset)])
>              os.system('git checkout -b %s %s' % (hgbranch[str(cset)], hgvers[parent]))
>          else:
> -            print 'checking out branch', hgbranch[str(cset)]
> +            print('checking out branch', hgbranch[str(cset)])
>              os.system('git checkout %s' % hgbranch[str(cset)])
>  
>      # merge
> @@ -209,7 +209,7 @@ def getgitenv(user, date):
>              otherbranch = hgbranch[mparent]
>          else:
>              otherbranch = hgbranch[parent]
> -        print 'merging', otherbranch, 'into', hgbranch[str(cset)]
> +        print('merging', otherbranch, 'into', hgbranch[str(cset)])
>          os.system(getgitenv(user, date) + 'git merge --no-commit -s ours "" %s %s' % (hgbranch[str(cset)], otherbranch))
>  
>      # remove everything except .git and .hg directories
> @@ -233,12 +233,12 @@ def getgitenv(user, date):
>  
>      # delete branch if not used anymore...
>      if mparent and len(hgchildren[str(cset)]):
> -        print "Deleting unused branch:", otherbranch
> +        print("Deleting unused branch:", otherbranch)
>          os.system('git branch -d %s' % otherbranch)
>  
>      # retrieve and record the version
>      vvv = os.popen('git show --quiet --pretty=format:%H').read()
> -    print 'record', cset, '->', vvv
> +    print('record', cset, '->', vvv)
>      hgvers[str(cset)] = vvv
>  
>  if hgnewcsets >= opt_nrepack and opt_nrepack != -1:
> @@ -247,7 +247,7 @@ def getgitenv(user, date):
>  # write the state for incrementals
>  if state:
>      if verbose:
> -        print 'Writing state'
> +        print('Writing state')
>      f = open(state, 'w')
>      pickle.dump(hgvers, f)
>  
>
> --
> https://github.com/git/git/pull/458