How do you do method chaining?

[nilamo]

How do you guys do method chaining?  Everything I've tried to break method calls across multiple lines looks pretty ugly.
Or do you guys just not do chaining at all?

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class query(object):     def __init__(self, source):         self.filters = []         self.source = source       def where(self, filter):         self.filters.append(filter)         return self       def get(self):         all_filters = lambda x: all(func(x) for func in self.filters)         return list(filter(all_filters, self.source))   things = query(range(1000)     ).where(lambda x: x % 2 == 0     ).where(lambda x: x % 3 == 0     ).where(lambda x: x % 4 == 0     ).where(lambda x: x % 5 == 0)   #things = query(range(1000)).where( #    lambda x: x % 2 == 0).where( #    lambda x: x % 3 == 0).where( #    lambda x: x % 4 == 0).where( #    lambda x: x % 5 == 0)   print(things.get())

Output:
[0, 60, 120, 180, 240, 300, 360, 420, 480, 540, 600, 660, 720, 780, 840, 900, 960]

[Mekire]

Not quite sure if this is what you are going for but it gives the same results:

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from functools import partial   # ... class definition   def divisible_by(div, num):     return num % div == 0   things = query(range(1000))   for i in (2,3,4,5):     things.where(partial(divisible_by, i))

Or even:

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from functools import partial   # ... class definition   def divisible_by(div, num):     return num % div == 0   things = query(range(1000))   things.filters = [partial(divisible_by, i) for i in (2,3,4,5)]

[nilamo]

Yeah, that gives the same results, but it was just a toy class to demonstrate where it could syntactically be useful.  
What if each filter was unrelated from the others?  Like, what if it's a wrapper around BeautifulSoup, and each query is a sub-selector of the parent filter's result?

The original example could also be written like this, though I think using backslashes looks worse than the dangling parentheses...

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things = query(range(1000)) \    .where(lambda x: x % 2 == 0) \    .where(lambda x: x % 3 == 0) \    .where(lambda x: x % 4 == 0) \    .where(lambda x: x % 5 == 0)

[volcano63]

The original example could also be written like this, though I think using backslashes looks worse than the dangling parentheses...

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things = query(range(1000)) \    .where(lambda x: x % 2 == 0) \    .where(lambda x: x % 3 == 0) \    .where(lambda x: x % 4 == 0) \    .where(lambda x: x % 5 == 0)

Actually - while I hate backlashes - I would rather use this option - it's ugly but it's more obvious

[nilamo]

If we rewrite the original class to be immutable (...as was my initial intention, but I wrote it fast), it becomes a little more clear why I'm aiming for this.

I guess using temporary variables or just having multiple filters/selectors on a single line is the way to go.

Here's probably a better example:

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class query(object):     def __init__(self, source, filters = ()):         self.filters = filters         self.source = source       def where(self, filter):         filters = self.filters + (filter, )         new_query = query(self.source, filters)         return new_query       def __and__(self, other):         filters = self.filters + other.filters         return query(self.source, filters)       def get(self):         all_filters = lambda x: all(func(x) for func in self.filters)         return list(filter(all_filters, self.source))   things = query(range(1000))   by_9 = things.where(lambda x: x % 9 == 0)   only_odd = things.where(lambda x: x % 2 != 0) further_filtered = only_odd.where(lambda x: x % 3 == 0).where(lambda x: x % 7 == 0)   print((further_filtered & by_9).get()) # [63, 189, 315, 441, 567, 693, 819, 945]

[Mekire]

Yes, as to your original lambda chaining; I would absolutely never do that and it makes my eyes bleed, if that is the answer you were looking for. That is why I proposed an alternative. xD

If a library I was using forced me to code this way I would really try to find an alternative library as well.