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Re: DataStructure
Posted: Sat Apr 20, 2013 4:38 pm
by BorisTheOld
This is an interesting request, but is probably not necessary, since there's a simple way of implementing it.
The 20,000+ items presumably already exist in a file which must be converted into source code. The Data Section would look something like this:
Code: Select all
DataSection
IncludeFile "filename"
EndDataSection
We use a small program to convert the original data file into a series of Data statements, with the data converted into 4-byte hex constants, such as:
When our application starts, the encoded data in the DataSection is expanded into arrays for ease of processing.
It's a simple technique that can handle all types of data, and gets around the problem of having to provide customers with small data files as well as the executable code.
Re: DataStructure
Posted: Sun Apr 21, 2013 11:02 pm
by bosker
Well, everybody else is necro-posting
...
Since the original post in this thread, some things have been added to PB that make it possible to do what I think Michael wanted
without copying data. A few structures and macros is all it takes.
The following test code reveals all (I hope)...
Code: Select all
EnableExplicit
Structure TCity ; a single city data
Name.s
Country.a
x.f
y.f
EndStructure
Structure TCities ; a whole bunch of cities
City.TCity[0] ; this works for any number (but may be considered flaky)
EndStructure
Macro mCity(Name, Country, x, y) ; Declare of a single city (keeps all data together)
Data.i @ Name ; address of name string
Data.a Country
Data.f x, y
EndMacro
; Test code
Define *Cities.TCities = ?CityData
Define i.l
OpenConsole()
Repeat
With *Cities\City[i]
If \Name <> "XXXX"
PrintN(\Name + ", " + Str(\Country) + " at " + StrF(\x) + ", " + StrF(\y))
Else
Break
EndIf
EndWith
i + 1
Forever
PrintN("Done!")
DataSection
CityData:
mCity("Andorra la Vella", 1, 42.51, 1.51)
mCity("Les Escaldes", 1, 42.50, 1.53)
mCity("Abu Zabi", 2, 24.48, 54.37)
mCity("Khawr Fakkan", 2, 25.34, 56.36)
Data.i @"XXXX" ; terminator (if you like)
EndDataSection
Re: DataStructure
Posted: Mon Apr 22, 2013 12:15 am
by skywalk
Thank you bosker!
Better to post later than never!
Hadn't thought to try a macro in a DataSection.
This solves an annoying problem I had with losing track of which position I was in while editing a data line.
Now with the macro, I get context help. Really cool.
Re: DataStructure
Posted: Mon Apr 22, 2013 2:39 am
by BorisTheOld
Of course, a more simple approach is to not use a DataSection to store the data, but to assign it directly to some other data structure, such as an array. It all depends on the application and the nature of the data.
The solution depends on many things. For instance, is the data in memory accessed sequentially or by one or more key fields? Will an array or map work best? Or should the data be written to a random access file for the duration of the program run?
The trick is not to get hung up on a particular approach, but to be creative and think outside the box.
Mostly, we write embedded data to indexed files in order to do keyed lookups, but for a few situations we embed binary data in a DataSection.
Re: DataStructure
Posted: Mon Apr 22, 2013 7:45 am
by davido
bosker:
Very, very clever!
Re: DataStructure
Posted: Mon Apr 22, 2013 6:39 pm
by Michael Vogel
bosker wrote:Well, everybody else is necro-posting
[...]
I love that
