Re: [bug-recutils] Value Expressions

[John Darrington]

On Tue, Sep 04, 2012 at 10:36:20AM +0200, Jose E. Marchesi wrote:
     
              Looks good but, what if you want to add a value that starts with 
a /
              character?  We must find a simple, complete and easy to learn 
syntax for
              this...
         
         This is always going to be a problem as soon as you introduce any kind 
of expression
         which is to be interpreted other than literally.  The obvious answer 
is, you must 
         escape the / with a \  Another solution is, to introduce a new option 
-A; -A would
         take a string to be interpreted as a value  expression, -a would be 
interpreted 
         literally.
         
         The trick is, like you say, is to find the solution which puts the 
least confusion
         on the users.
     
     Yes.  We need more ideas.

Well I think it should be similar to other GNU utilities.  And I think that 
recset is somewhat
analagous to sed and to tr, so the syntax ought to be familar to users of those 
utilies.  Agreed?

So to set a fieldvalue to something based on another fieldvalue:

# Add an email address based on first and last names
recset  -f EMail -[aSa] 'address@hidden'

# Mutate all email addresses to lower case
recset -f Email -s '{Email}/[:upper:]/[:lower:]/'

# Our company rules say that email addresses may not begin with a digit.  So 
prepend an X
recset -f Email -s '{Email}/^\([0-9])/X\1/'


This does not address the problem of somebody who wants to insert a literal 
'{FieldName}' or similar.
I don't think this would happen very often. But they could to it with:

recset -f Email -s '\{Email\}'

In addition you could introduce a new option -l which means all further values 
to be interpreted 
literally:

 
# Add an Email address based on the first and last names, and  a password of 
{xfk%}$sO0/g
recset  -f Email -a 'address@hidden' -l -f Password -a '{xfk%}$sO0/g' 

Would that cover most use cases?



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