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Date: Thu, 22 May 2014 09:58:57 -0700 (PDT)
From: Albert-Jan Roskam <fomcl@yahoo.com>
Subject: shebang & windows: call an extensionless git hook
To: Python <python-list@python.org>
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Reply-To: Albert-Jan Roskam <fomcl@yahoo.com>
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Hi,=0A=0AI wrote the git pre-commit hook below. It is supposed to reject co=
mmits that contain large files (e.g. accidental commits by inexperienced us=
ers, think of "git add .")=0A=0A=0AAnyway, I tried this under Linux, but th=
e target platform is Windows. As per Git design the hook name *must* be "pr=
e-commit" (no .py extension). How will Windows know that Python should be r=
un? And (should it be relevant): how does Windows know which Python version=
 to invoke? I read about custom shebangs with Pylauncher. Is that my only o=
ption? (see: https://bitbucket.org/vinay.sajip/pylauncher, http://legacy.py=
thon.org/dev/peps/pep-0397/)=0A=0A=0AIn addition, I would really appreciate=
 general feedback on the hook script below.=A0=0A=0AThanks!=0A=0AAlbert-Jan=
=0A=0Aalbertjan@debian ~/Desktop/test_repo $ git config --global init.templ=
atedir ~/Desktop/git_template_dir=0Aalbertjan@debian ~/Desktop/test_repo $ =
cd ~/Desktop/git_template_dir=0Aalbertjan@debian ~/Desktop/git_template_dir=
 $ cat hooks/pre-commit=0A#!/usr/bin/python=0A#-*- mode: python -*-=0A=0A""=
"Git pre-commit hook: reject large files"""=0A=0Aimport=0Asys=0Aimport os=
=0Aimport re=0Afrom subprocess import Popen, PIPE=0A=0Adef git_filesize_hoo=
k(megabytes_cutoff=3D5, verbose=3DFalse):=0A=A0=A0=A0 """Git pre-commit hoo=
k: Return error if the maximum file size in the HEAD=0A=A0=A0=A0 revision e=
xceeds <megabytes_cutoff>, succes (0) otherwise. You can bypass =0A=A0=A0=
=A0 this hook by specifying '--no-verify' as an option in 'git commit'."""=
=0A=A0=A0=A0 if verbose: print os.getcwd()=0A=A0=A0=A0 cmd =3D "git ls-tree=
 --full-tree -r -l HEAD"=0A=A0=A0=A0 git =3D Popen(cmd, shell=3DTrue, stdou=
t=3DPIPE, cwd=3Dos.getcwd())=0A=A0=A0=A0 get_size =3D lambda item: int(re.s=
plit(" +",=0Aitem)[3].split("\t")[0])=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 =0A=A0=
=A0=A0 sizes =3D map(get_size, git.stdout.readlines())=0A=A0=A0=A0 cut_off_=
bytes =3D megabytes_cutoff * 2 ** 20=0A=A0=A0=A0 if max(sizes) > cut_off_by=
tes:=0A=A0=A0=A0=A0=A0=A0=A0 return ("ERROR: your commit contains at least =
one file "=0A=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 "that is larger =
than %d bytes" % cut_off_bytes)=0A=A0=A0=A0 return 0=0A=0Aif __name__ =3D=
=3D "__main__":=0A=A0=A0=A0 sys.exit(git_filesize_hook(0.000001, True))=0A=
=0Aalbertjan@debian ~/Desktop/git_template_dir $ cd -=0A/home/antonia/Deskt=
op/test_repo=0Aalbertjan@debian ~/Desktop/test_repo $ git init=A0 ## this a=
lso fetches my own pre-commit hook from template_dir=0AInitialized empty Gi=
t repository in /home/antonia/Desktop/test_repo/.git/=0Aalbertjan@debian ~/=
Desktop/test_repo $ touch foo.txt=0Aalbertjan@debian ~/Desktop/test_repo $ =
git add foo.txt=0Aalbertjan@debian ~/Desktop/test_repo $ ls -l .git/hooks=
=0Atotal 4=0A-rw-r--r-- 1 albertjan albertjan 1468 May 22 14:49 pre-commit=
=0Aalbertjan@debian ~/Desktop/test_repo $ git commit -a -m "commit"=A0=A0 #=
#### hook does not yet work=0A[master (root-commit) dc82f3d] commit=0A=A00 =
files changed=0A=A0create mode 100644 foo.txt=0Aalbertjan@debian=0A~/Deskto=
p/test_repo $ chmod +x .git/hooks/pre-commit=A0=A0 ###### can I avoid this =
in Linux? What should I do in Windows?=0Aalbertjan@debian ~/Desktop/test_re=
po $ echo "blaah\n" >> foo.txt=0Aalbertjan@debian ~/Desktop/test_repo $ git=
 commit -a -m "commit"=A0 ##### now the hook does its job=0A/home/antonia/D=
esktop/test_repo=0AERROR: your commit contains at least one file that is la=
rger than 1 bytes=0A=0ARegards,=0A=0AAlbert-Jan=0A=0A=0A=0A=0A~~~~~~~~~~~~~=
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=0A=0AAll right, b=
ut apart from the sanitation, the medicine, education, wine, public order, =
irrigation, roads, a =0A=0Afresh water system, and public health, what have=
 the Romans ever done for us?=0A=0A=A0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~