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From: ram@zedat.fu-berlin.de (Stefan Ram)
Newsgroups: comp.lang.python
Subject: A technique from a chatbot
Date: 2 Apr 2024 17:18:16 GMT
Organization: Stefan Ram
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  Some people can't believe it when I say that chatbots improve
  my programming productivity. So, here's a technique I learned
  from a chatbot!
  
  It is a structured "break". "Break" still is a kind of jump,
  you know?
  
  So, what's a function to return the first word beginning with
  an "e" in a given list, like for example
  
[ 'delta', 'epsilon', 'zeta', 'eta', 'theta' ]

  ? Well it's
  
def first_word_beginning_with_e( list_ ):
    for word in list_:
        if word[ 0 ]== 'e': return word

  . "return" still can be considered a kind of "goto" statement.
  It can lead to errors:

def first_word_beginning_with_e( list_ ):
    for word in list_:
        if word[ 0 ]== 'e': return word
    something_to_be_done_at_the_end_of_this_function()
    
  The call sometimes will not be executed here!
  So, "return" is similar to "break" in that regard.
  
  But in Python we can write:
  
def first_word_beginning_with_e( list_ ):
    return next( ( word for word in list_ if word[ 0 ]== 'e' ), None )
    
  . No jumps anymore, yet the loop is aborted on the first hit
  (if I guess correctly how its working).
  
  And it is this combination of "next", a generator, and "None" that
  the chatbot showed me when I asked him how to get the first component
  of a list that matches a condition!
  
  PS: Let's verify the earliness of the exit out of the loop:
  
  Main.py
  
def list_():
    list__ =[ 'delta', 'epsilon', 'zeta', 'eta', 'theta' ]
    for entry in list__:
        print( f'Now yielding {entry}.' )
        yield entry

def first_word_beginning_with_e( list_ ):
    return next( ( word for word in list_() if word[ 0 ]== 'e' ), None )

print( first_word_beginning_with_e( list_ ))

   sys.stdout
   
Now yielding delta.
Now yielding epsilon.
epsilon