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Make implicit structures explicit

• From: "Costello, Roger L." <costello@mitre.org>
• To: "xml-dev@lists.xml.org" <xml-dev@lists.xml.org>
• Date: Tue, 8 Apr 2014 20:09:21 +0000

Hi Folks,

Suppose that you document the steps to be taken by an aircraft in its landing procedure:

1. Contact control tower

2. Enter glide slope

3. Correct for wind conditions

Suppose those things must be followed in the sequence listed.

The XML could be designed like this:

<aircraft-approach-procedure>
    <transition>Contact control tower</transition>
    <transition>Enter glide slope</transition>
    <transition>Correct for wind conditions</transition>
</aircraft-approach-procedure>

That design relies (implicitly) on the order of the <transition> elements for denoting the sequence of steps to be taken. 

An alternative design is to (explicitly) specify the order. Here is one way to accomplish this:

<aircraft-approach-procedure>
    <transition step="2">Enter glide slope</transition>
    <transition step="3">Correct for wind conditions</transition>
    <transition step="1">Contact control tower</transition>
</aircraft-approach-procedure>

Note that in this design it is not necessary to list the <transition> elements in a particular order since @step explicitly indicates the order.

I vote for the latter as best practice. I invoke this principle as my justification: 

 	Make implicit structures explicit.

What do you think?

/Roger

• Follow-Ups:
  • RE: Make implicit structures explicit
    • From: "Costello, Roger L." <costello@mitre.org>
  • Re: Make implicit structures explicit
    • From: Michael Kay <mike@saxonica.com>
  • Re: Make implicit structures explicit
    • From: Arjun Ray <arjun.ray@verizon.net>
  • RE: Make implicit structures explicit
    • From: "Costello, Roger L." <costello@mitre.org>
  • Re: Make implicit structures explicit
    • From: Frank Manola <fmanola@acm.org>
  • Re: Make implicit structures explicit
    • From: Amelia A Lewis <amyzing@talsever.com>
  • Re: Make implicit structures explicit
    • From: Ihe Onwuka <ihe.onwuka@gmail.com>