[Tutor] Escape sequences

[Kent Johnson]

David Heiser wrote:
> I have code that assigns escape sequences to variables like
> "self.resetString = '\03'". As long as they are hard coded in,
> everything works fine.
> 
> But I want to read the variable from a text/config file so my users can
> override the defaults. In the file are a list of "parameter = value"
> pairs like "resetString = \03". As the file is parsed, each pair is
> stored in a dictionary; "parmeterDictionary[parameter] = value".
> 
> Then in the code, the value is assigned to the variable with a statement
> like "self.resetString = parmeterDictionary['resetString']".
> 
> Simple ASCII strings work fine, but the escape sequences don't work and
> the code fails. "print self.resetString" returns "\\03", instead of a
> nonprintable character.

Use the 'string_escape' codec to decode the escaped strings:

In [1]: s= '\\03'

In [2]: s
Out[2]: '\\03'

In [3]: len(s)
Out[3]: 3

In [4]: s.decode('string_escape')
Out[4]: '\x03'

In [5]: len(_)
Out[5]: 1

Kent