Modularity goes hand-in-hand with the DRY principle. When creating a complex logic, it is good practice to break it down, and each piece of code should only do one thing. By creating modular code we are also creating reusable code.
Compare the following two pieces of code:
def dashboard(request):
if request.method != 'GET':
return HttpResponseNotAllowed('GET')
if request.user.is_anonymous:
return redirect(request, reverse('login'))
return render(request, 'dashboard.html')
@require_GET
@login_required
def dashboard(request):
return render(request, 'dashboard.html')
Or even this:
def dashboard(request):
if request.method == 'GET':
if not request.user.is_anonymous:
return render(request, 'dashboard.html')
else:
return redirect(request, reverse('login'))
else:
return HttpResponseNotAllowed('GET')
The snippet with decorators has a very clear, untwisted logic.