I have a wtform which has a list of days and start and end time:
form.mon_start
form.mon_end
form.tues_start
form.tues_end
...
I have to set these often and I would like to loop through a list of days and set them in one loop. Something like:
days = ['mon','tues','weds','thurs','fri','sat','sun']
for day in days:
form.[day + '_start'] = #some datetime setting
form.[day + '_end'] = #some datetime setting
Is this possible?
You can use setattr(object, attribute, value):
days = ['mon','tues','weds','thurs','fri','sat','sun']
for day in days:
setattr(form, day + '_start', start_value)
setattr(form, day + '_end', end_value)
This sets the attribute to value on a given object.
setattr(g.currentschool.school_hours,day + '_end',end_value)
getattr(form,day + '_start').choices. Setting a variable from the dynamic one you got by string.g.currentschool.school_hours is evaluated as ordinary and results in an object (setattr and friends are not special, just ordinary functions). So if you want to set the attribute on the object this evaluates to, then yes that works. Likewise, the getattr call in your second comment just evaluates to an object like every other function call, and if you want to read the choices attribute of the object it results in, then yes that works. These functions aren't magic.Objects can be thought of as juiced up dictionaries. In fact, they have a dict. So try this:
days = ['mon','tues','weds','thurs','fri','sat','sun']
for day in days:
form.__dict__[day + '_start'] = #some datetime setting
form.__dict__[day + '_end'] = #some datetime setting
And you'll get what you want. But its a bit hackish.
The function setattr(, ) does the same thing, its just an explicit (non-hackish) way of doing this, and it should be supported in the future regardless whatever winds up happening to the dict:
days = ['mon','tues','weds','thurs','fri','sat','sun']
for day in days:
for mark in [('start', gen_start_func), ('end', gen_end_func)]:
setattr(form, '_'.join([day, mark[0]]), mark[1]())
So in the last version we're using setattr() and we're using an inner loop that operates over a tuple containing (, ). Its a different way of doing things which may or may not be more readable, depending on the problem you're trying to solve and the type of code you are used to reading.
getattr / setattr is NOT the same thing as directly accessing the object's __dict__. In the first case you'll trigger the attribute lookup mechanism, which will take proper care of computed attributes, inheritence, dynamic attribute resolution etc. In the second case you totally bypass it, which may yield very unexpected results. Also not all types have a __dict__ (read about slots for more about it).