[Tutor] (no subject)

[Sean 'Shaleh' Perry]

On Tuesday 23 December 2003 15:19, arkamir at softhome.net wrote:
> Hello,
>
> I have a question concerning turning strings into variables.
>
> Say I have a list like x:
>
> x = ['hello', 'bye']
>
> What I need is the final result to look like this, or the equivelant of
> this. How would I do this???
>
> hello = re.compile(r'<!--INSERT HELLO HERE-->')
> bye = re.compile(r'<!--INSERT BYE HERE-->')
>
> I think it would look something like
>
> for y in x:
>   #string to variable# = re.compile(r'<--INSERT %s HERE-->' % y)
>
> Is this the most effecient way,

hmm, perhaps I am not fully understanding you, but would this work?

transforms = { 'hello': '<!-- INSERT HELLO HERE -->', 'bye': '<!-- INSERT BYE 
HERE -->' }
for y in x:
  if y in transforms:
    print transforms[y]

If this is not what you meant, how about specifying your needs by giving us 
some sample input and output?  For example if we start with:

Hello, World!

we should end up with:

<!-- Hello -->, World!

> and how would I convert y to capitols.

>>> name = 'bob'
>>> name.title()
'Bob'
>>> name.upper()
'BOB'

>
> Also can someone explain lambdas too me. Whenever I do something like:
>

in general you should stick to asking one type of question at a time.  Makes 
it easier for people to follow the thread and especially for people searching 
the archives later on.

> x = lambda x: x + 1, (1)
>
> I get (<function whatever blah>, 2)
>

lambda is a way to generate small functions during execution instead of during 
compilation / parsing.  It is used most often for event handlers where the 
action is usually simple and used once so defining a function would make the 
program longer or harder to follow.  People who like to program in a more 
functional (instead of OO) style like to use it as well.

For instance:

for word in map(lambda y: y.upper(), x): # re-use you list from above
    print word

Current python uses a different idiom:

for word in [ y.upper() for y in x ]:
    print word

You can write plenty of python and never use lambda.  Especially with python 
2.2 and newer.