locals() and dictionaries

[JerryB]

Hi,
I have a dictionary, a string, and I'm creating another string, like
this:

dict = {}
dict[beatles] = "need"
str = "love"

mystr = """All you %(dict[beatles])s is %(str)s""" % locals()

Why do I get
keyerror: 'dict[one]'?

Is there a way to reference the elements in a dictionary with locals()
or do I need to create a temp variable, like

need = dict[one]
mystr = """All you %(need)s is %(str)s"""

[Rocco Moretti]

Re: locals() and dictionaries

JerryB wrote:[color=blue]
> Hi,
> I have a dictionary, a string, and I'm creating another string, like
> this:
>
> dict = {}
> dict[beatles] = "need"
> str = "love"
>
> mystr = """All you %(dict[beatles])s is %(str)s""" % locals()
>
> Why do I get
> keyerror: 'dict[one]'?
>
> Is there a way to reference the elements in a dictionary with locals()
> or do I need to create a temp variable, like
>
> need = dict[one]
> mystr = """All you %(need)s is %(str)s"""[/color]

1) Avoid variable names like 'dict' and 'str'- they cover up the builtin
names.

2) When showing error, don't retype - cut and paste:
[color=blue][color=green][color=darkred]
>>> dict[beatles] = "need"[/color][/color][/color]

Traceback (most recent call last):
File "<pyshell#6 >", line 1, in -toplevel-
dict[beatles] = "need"
NameError: name 'beatles' is not defined[color=blue][color=green][color=darkred]
>>> dict['beatles'] = "need"
>>>[/color][/color][/color]

3) In string formating, the item in parenthesis, used as a string, is
the key for the dictionary. That is:

"""All you %(dict[beatles])s is %(str)s""" % ld

is the same as

"""All you %s is %s""" % (ld['dict[beatles]'],ld['str'])

4) Your best bet is not to use locals(), but to create a new dictionary
with the appropriate keys. E.g.:
[color=blue][color=green][color=darkred]
>>> d = {}
>>> d['beatles'] = "need"
>>> s = "love"
>>> d2 = d.copy()
>>> d2['str'] = s
>>> d['str'][/color][/color][/color]

Traceback (most recent call last):
File "<pyshell#2 4>", line 1, in -toplevel-
d['str']
KeyError: 'str'[color=blue][color=green][color=darkred]
>>> d2['str'][/color][/color][/color]
'love'[color=blue][color=green][color=darkred]
>>> mystr = """All you %(beatles)s is %(str)s""" % d2
>>> print mystr[/color][/color][/color]
All you need is love

[JerryB]

Re: locals() and dictionaries

Rocco:
thanks for your response. The examples were just made up. I don't
normally use 'dict' and 'str'.
I know I can create a dictionary with the variables I want, etc. My
question is not how to solve the problem, or how to come up with a
work-around (I'm getting pretty good at this one :), so my question
stands:

is it possible to access the individual members of a dictionary using %
locals() when creating a string?

Thank you again for your suggestions.
Jerry

[Alex Martelli]

Re: locals() and dictionaries

JerryB <grblanco@gmail .com> wrote:
...[color=blue]
> is it possible to access the individual members of a dictionary using %
> locals() when creating a string?[/color]

Not by using the built-in locals(); you'd have to override locals to
mean someting different (not recommended).


Alex

[Kent Johnson]

Re: locals() and dictionaries

JerryB wrote:[color=blue]
> Rocco:
> thanks for your response. The examples were just made up. I don't
> normally use 'dict' and 'str'.
> I know I can create a dictionary with the variables I want, etc. My
> question is not how to solve the problem, or how to come up with a
> work-around (I'm getting pretty good at this one :), so my question
> stands:
>
> is it possible to access the individual members of a dictionary using %
> locals() when creating a string?[/color]

You might want to use a more powerful templating engine, for example
http://cheetahtemplate.org/ and probably many others.

Kent