Re: first of not None

[Serge Matveenko]

On 10/9/08, Serge Matveenko [EMAIL PROTECTED] wrote:
 I need to put in the var property of the first object from the list
 that is not None. Somth like:

 foo = first_of([any, beny, riki,]).name

 Dont want to ugly if-cascade:

 foo = any.name if name is not None else beny.name if beny is not None \
 else riki.name if riki is not None

after some play with interpreter and Python logic i've got this:

objs = [None, 'dfgh', None,]
obj_l = [obj.__len__() for obj in objs if obj is not None][0]

Now the question is this is lazy or not? And how could i make it lazy?


-- 
Serge Matveenko
mailto:[EMAIL PROTECTED]
http://serge.matveenko.ru/
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Re: first of not None

[Diez B. Roggisch]

Serge Matveenko schrieb:

On 10/9/08, Serge Matveenko [EMAIL PROTECTED] wrote:

I need to put in the var property of the first object from the list
that is not None. Somth like:

foo = first_of([any, beny, riki,]).name

Dont want to ugly if-cascade:

foo = any.name if name is not None else beny.name if beny is not None \
else riki.name if riki is not None


after some play with interpreter and Python logic i've got this:

objs = [None, 'dfgh', None,]
obj_l = [obj.__len__() for obj in objs if obj is not None][0]



The usual way to compute the len is to use

len(obj)



Now the question is this is lazy or not? And how could i make it lazy?


No, it's not. You could make it a generator expression:


obj_l = (len(obj) for obj in objs if obj is not None).next()

Diez
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first of not None

[Serge Matveenko]

Hello, everybody!

Could someone help me with coding this thing?

I need to put in the var property of the first object from the list
that is not None. Somth like:

foo = first_of([any, beny, riki,]).name

Dont want to ugly if-cascade:

foo = any.name if name is not None else beny.name if beny is not None \
else riki.name if riki is not None


-- 
Serge Matveenko
mailto:[EMAIL PROTECTED]
http://serge.matveenko.ru/
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Re: first of not None

[Bruno Desthuilliers]

Serge Matveenko a écrit :

Hello, everybody!

Could someone help me with coding this thing?

I need to put in the var property of the first object from the list
that is not None. Somth like:

foo = first_of([any, beny, riki,]).name

Dont want to ugly if-cascade:

foo = any.name if name is not None else beny.name if beny is not None \
else riki.name if riki is not None



def not_none(obj):
return obj is not None

def first_of(seq, predicate=not_none, default=None):
for obj in seq:
if predicate(obj):
return obj
else:
return default

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Re: first of not None

[Tim Chase]

I need to put in the var property of the first object from the list
that is not None. Somth like:

foo = first_of([any, beny, riki,]).name

Dont want to ugly if-cascade:

foo = any.name if name is not None else beny.name if beny is not None \
else riki.name if riki is not None



assuming you meant foo = any.name if ***any*** is not None else 
beny.name...


If you have a fixed/hard-coded list of elements, you could 
something like:


  foo = (any or beny or riki).name

If you have dynamic list of elements:

  class NoElementFound(Exception): pass
  def first(iterable):
for element in iterable:
  if element: return element
raise NoElementFound

  lst = [any, beny]
  if condition: lst.append(riki)
  print first(lst).name

This first() is about the functionality of the SQL Coalesce() 
function.


Hope this helps,

-tim



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