Chaining class decorators

The last (i.e. outer) decorator's behavior gets executed first.

def require_authentication_permission(permission):
    def decorator(cls):
        cls.dispatch = method_decorator(
            permission_required(
                permission, raise_exception=True)
            )(cls.dispatch)
        cls2 = class_login_required(cls)
        return cls2

    return decorator

In this case, the execution order is:

1. class_login_required
2. permission_required

Logging in Django

To log to console in Django. Source: Logging | djangoproject.com

settings.py 

LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'handlers': {
        'console': {
            'class': 'logging.StreamHandler',
        },
    },
    'loggers': {
        'django': {
            'handlers': ['console'],
            'level': os.getenv('DJANGO_LOG_LEVEL', 'INFO'),
        },
    },
}

File that uses logging

import logging

logger = logging.getLogger('django')

Write to log

logger.info('Hello')

Disable highlighting links in Vim

 By default, Vim underlines the text inside anchor tags, including spaces, e.g.:

   Some text

To disable this, create ~/.vim/syntax/html.vim:

" disable the current htmlLink syntax
highlight link htmlLink text

Mapping Keys in Mac OS 10.12 Sierra

To map keys in Mac OS 10.12 Sierra, install Karabiner-Elements.

I have a UK keyboard but am used to the US layout, so I've changed the section symbol § for the grave symbol `.

Being a vim user, I also like having

1. the esc key next to the shift key
2. the right command key act as a control key

Block domains on search engine results

Greasemonkey script to allow blocking of domains in search engine results. Works for Google, Duckduckgo and various other search engines.

Google Hit Hider by Domain (Search Filter / Block Sites)

Django Forms

Some common uses of Django Forms.

f = Form(request.POST)
Instantiating a form with data a dictionary, e.g. from POST, creates a form populated with the field-name & field-value pairs in the dictionary.

f.errors
Returns dictionary of errors with keys being field names.

f['field_name'].errors
Returns list of errors for the specified field.

bound_form = self.form_class(request.POST)
return render(request, self.template_name, {'form': bound_form})
In a class-based view, renders a form with data bound from POST. bound_form.is_bound returns True.

model_instance = get_object_or_404(
            self.form_class.Meta.model, slug__iexact=slug)
bound_form = self.form_class(request.POST, instance=model_instance)
As with previous line, renders a form with data bound from POST but also associated with a model instance so that it can be modified with a subsequent:
model_instance = bound_form.save()

form_class(initial={'title': 'Something'})
Creates a form with a field filled in already. However, the form is not bound.

Hide vim swap files in vim browser

While browsing files with vim, e.g. by entering the command ":e .", you might see a lot of swap files (*.swp, *.sw?) if you're using buffers. To hide them:

:let g:netrw_list_hide= '.*\.sw\w$'

Bash Colors

#!/bin/bash
#
#   This file echoes a bunch of color codes to the 
#   terminal to demonstrate what's available.  Each 
#   line is the color code of one forground color,
#   out of 17 (default + 16 escapes), followed by a 
#   test use of that color on all nine background 
#   colors (default + 8 escapes).
#

T='gYw'   # The test text

echo -e "\n                 40m     41m     42m     43m\
     44m     45m     46m     47m";

for FGs in '    m' '   1m' '  30m' '1;30m' '  31m' '1;31m' '  32m' \
           '1;32m' '  33m' '1;33m' '  34m' '1;34m' '  35m' '1;35m' \
           '  36m' '1;36m' '  37m' '1;37m';
  do FG=${FGs// /}
  echo -en " $FGs \033[$FG  $T  "
  for BG in 40m 41m 42m 43m 44m 45m 46m 47m;
    do echo -en "$EINS \033[$FG\033[$BG  $T  \033[0m";
  done
  echo;
done
echo 

Source: http://www.tldp.org/HOWTO/Bash-Prompt-HOWTO/x329.html

Create React Apps

https://github.com/facebookincubator/create-react-app

Disable mouse acceleration on Mac

Mouse acceleration makes it hard for me to point and click things based on muscle memory, so I turn it off by entering into the terminal:

defaults write .GlobalPreferences com.apple.mouse.scaling -1

Optionally, you can make an alias in ~/.profile and just enter the alias when you need to re-disable it, which you'll have to do often as the Mac resets this when you adjust mouse speed and sometimes upon login:

alias ma="defaults read .GlobalPreferences com.apple.mouse.scaling; defaults write .GlobalPreferences com.apple.mouse.scaling -1"

Note that the first command prints the current mouse acceleration, and the second one changes it.

Please let me know if you know a clean way to persist this setting.

Call C DLL from Python

http://www.lejordet.com/2009/04/simple-python-ctypes-example-in-windows/

Vim for Python

Option 1

~/.vimrc

syntax enable
if !exists("autocommands_loaded")
  let autocommands_loaded = 1
    autocmd BufRead,BufNewFile,FileReadPost *.py source ~/.vim/python
    endif

    " This beauty remembers where you were the last time you edited the file, and returns to the same position.
    au BufReadPost * if line("'\"") > 0|if line("'\"") <= line("$")|exe("norm '\"")|else|exe "norm $"|endif|endif

~/.vim/python

" The magical turn-Vim-into-a-Python-IDE vim resource file!
"
" Mostly taken from http://www.sontek.net/category/Vim.aspx
" Other bits culled from various sources, Canonical guys, or made up by me.
"
" Julian Edwards 2008-05-30

" Wrapping and tabs.
set tw=78 ts=4 sw=4 sta et sts=4 ai

" More syntax highlighting.
let python_highlight_all = 1

" Smart indenting
set smartindent cinwords=if,elif,else,for,while,try,except,finally,def,class

" Auto completion via ctrl-space (instead of the nasty ctrl-x ctrl-o)
set omnifunc=pythoncomplete#Complete
inoremap

" Wrap at 72 chars for comments.
set formatoptions=cq textwidth=72 foldignore= wildignore+=*.py[co]

" Highlight end of line whitespace.
highlight WhitespaceEOL ctermbg=red guibg=red
match WhitespaceEOL /\s\+$/

" The next two highlight matches break the previous one, I don't know why.
" Show long lines.
"highlight LongLine guibg=red ctermbg=red
"match LongLine /\%>79v.\+/
" Highlight bzr merge markers.
"highlight MergeMarker guibg=red ctermbg=red
"match MergeMarker /^[<=>\|]\{7\}\( [A-Z]\+\)?$/

" `gf` jumps to the filename under the cursor.  Point at an import statement
" and jump to it!
python << EOF
import os
import sys
import vim
for p in sys.path:
    if os.path.isdir(p):
        vim.command(r"set path+=%s" % (p.replace(" ", r"\ ")))
EOF

" Use :make to see syntax errors. (:cn and :cp to move around, :dist to see
" all errors)
set makeprg=python\ -c\ \"import\ py_compile,sys;\ sys.stderr=sys.stdout;\ py_compile.compile(r'%')\"
set efm=%C\ %.%#,%A\ \ File\ \"%f\"\\,\ line\ %l%.%#,%Z%[%^\ ]%\\@=%m

" Execute a selection of code (very cool!)
" Use VISUAL to select a range and then hit ctrl-h to execute it.
python << EOL
import vim
def EvaluateCurrentRange():
    eval(compile('\n'.join(vim.current.range),'','exec'),globals())
EOL
map :py EvaluateCurrentRange()

" Use F7/Shift-F7 to add/remove a breakpoint (pdb.set_trace)
" Totally cool.
python << EOF
def SetBreakpoint():
    import re
    nLine = int( vim.eval( 'line(".")'))

    strLine = vim.current.line
    strWhite = re.search( '^(\s*)', strLine).group(1)

    vim.current.buffer.append(
       "%(space)spdb.set_trace() %(mark)s Breakpoint %(mark)s" %
         {'space':strWhite, 'mark': '#' * 30}, nLine - 1)

    for strLine in vim.current.buffer:
        if strLine == "import pdb":
            break
    else:
        vim.current.buffer.append( 'import pdb', 0)
        vim.command( 'normal j1')

vim.command( 'map :py SetBreakpoint()')

def RemoveBreakpoints():
    import re

    nCurrentLine = int( vim.eval( 'line(".")'))

    nLines = []
    nLine = 1
    for strLine in vim.current.buffer:
        if strLine == "import pdb" or strLine.lstrip()[:15] == "pdb.set_trace()":
            nLines.append( nLine)
        nLine += 1

    nLines.reverse()

    for nLine in nLines:
        vim.command( "normal %dG" % nLine)
        vim.command( "normal dd")
        if nLine < nCurrentLine:
            nCurrentLine -= 1

    vim.command( "normal %dG" % nCurrentLine)

vim.command( "map :py RemoveBreakpoints()")
EOF

Source: https://dev.launchpad.net/UltimateVimPythonSetup minus the pydoc.vim part, which breaks it on my machine.

Option 2

This setup is more like an IDE: VIM as Python IDE