I'm new to OOP and a lot of times I become stumped in situations similar to this example:
Task: Generate an XML document that contains information about a
person. Assume
the information is readily available in a database. Here is an example of
the structure:
<Person>
<Name>John Doe</Name>
<Age>21</Age>
<Address>
<Street>100 Main St.</Street>
<City>Sylvania</City>
<State>OH</State>
</Address>
<Relatives>
<Parents>
<Mother>
<Name>Jane Doe</Name>
</Mother>
<Father>
<Name>John Doe Sr.</Name>
</Father>
</Parents>
<Siblings>
<Brother>
<Name>Jeff Doe</Name>
</Brother>
<Brother>
<Name>Steven Doe</Name>
</Brother>
</Siblings>
</Relatives>
</Person>
Ok lets create a class for each tag (ie:
Person, Name, Age, Address)
Lets assume each class is only responsible for itself and
the
elements directly contained
Each class will know (have defined by
default)
the classes that are directly contained within them
Each
class will have a process() function that will add itself and its
childeren to
the XML document we are creating
When a child is drawn, as in
the previous line, we will have them call process() as well
Now we are in a recursive loop where each object draws their childeren
until all are drawn
But what if only some of
the tags need to be drawn, and
the rest are
optional? Some are optional based on if
the data exists (if we have
it, we must draw it), and some are optional based on
the preferences
of
the user generating
the document
How do we make sure each object
has
the data it needs to draw itself and it's childeren? We can pass
down a massive array through every object, but that seems shitty
doesnt it? We could have each object query
the database for it, but
thats a lot of queries, and how does it know what it's query is?
What
if we want to get rid of a tag later? There is no way to reference
them.
I've been thinking about this for 20 hours now. I feel like I am misunderstanding a design principle or am just approaching this all wrong. How would you go about programming something like this? I suppose this problem could apply to any senario where there are classes that create other classes, but
the classes created need information to run. How do I get
the information to them in a way that doesn't seem fucky?
Thanks for all of your time, this has been kicking my ass.
