Rewriting HL7 messages fails

[tomunger]

I'm working on a project that modifies HL7 messages and have run into a couple bugs. Your documentation say that the library may eventually contain the ability to create HL7.

1. Modifying a field to greater depth fails

MSH|^~\\&|field|rep1~rep2|

A call to

seg.assign_field("NewRep", 3, 1)

Will fail because the field object contains a string, not a repetition. The desired behavior is to replace the sting with a repetition containing the new value.

I have a fix for this.

2. Added fields are not escaped.

Fields get added through Segment.assign_fields(). My first thought was to add escaping to this method. However, this breaks several tests that construct HL7 message. It does not appear to break parsing, but it does break creation of ACK messages.

I'm not sure what a fix for this should be. Candidates:

• All code that adds fields call escape() explicitly.
• Code alternate to assign_fields() that escapes the value before writing.

If given some guidance, I'll implement that fix and then offer a pull request.

[tomunger]

I've submitted a pull request 54 with the changes I made