Save and load types

Hello i using Blitz3D for more then a year now. a first i was avoiding using types becaus they where hard to understand. Now i start understanding them and use them. For the most part everyting is working fine if i am using a type. But:

I am trying to save and load data from a type to a file.
Writing to a file works fine but when i want to load the file back it won't work.

here a exampple of source code i tested.

Type WorkMenuType
	Field ID
	Field Naam$
	Field LinkID
	Field XPos
	Field YPos
	Field Width
	Field Height
End Type



Dim WorkMenu.WorkMenuType (100)

For x = 0 To 100
	WorkMenu(x) = New WorkMenuType 
Next

If FileType ("MyTest.typ") = 1
	DeleteFile "MuTest.typ"
EndIf

outfile = WriteFile ("MyTest.typ")
For x = 0 To 100
	WriteString Outfile,Str(WorkMenu (x))
Next

CloseFile outfile

; All the above is working fine. when adding below an error comes up.

infile = ReadFile ("MyTest.typ")
For x = 0 To 100
	WorkMenu(x) = ReadString (Infile)
Next
CloseFile infile

Its generate a error "ILLIGAL TYPE CONVERSION"
If i leave the part of reading the file away. The program is running and saving the data fine.
why can i write to a file but not read the same way?

Because your writing the type "handle" into the file. Not the data in the type.
And using an array of types? why not just use types? Makes it MUCH simpler.
for example.
See, Each type has an "ID" a "Naam$" and the other things, then you just save each of those into the file, then when you load em, make a new type and put that data into it.

Type WorkMenuType
	Field ID
	Field Naam$
	Field LinkID
	Field XPos
	Field YPos
	Field Width
	Field Height
End Type



For x = 0 To 100
	W.Workmenutype = New Workmenutype
	W\ID=10
	W\Naam$="JoeBob"
	;;Etc, fill in whatever you want.
Next

If FileType ("MyTest.typ") = 1
	DeleteFile "MuTest.typ"
EndIf

outfile = WriteFile ("MyTest.typ")
For W.workmenuType= Each Workmenutype
	WriteString(File,W\ID)
	WriteString(File,W\Naam$)
	;;Once again, etc. Fill whatever you want in.
Next 
CloseFile outfile

; All the above is working fine. when adding below an error comes up.

infile = ReadFile ("MyTest.typ")
While Not Eof(infile)
	W.Workmenutype = New Workmenutype
	W\ID=ReadString(file)
	W\Naam$=ReadString(file)
	;;Once again, etc. Fill in whatever else you want to add.
Wend 
	
	
CloseFile infile

Hi

You are storing strings (not object handles) containing a comma separated list of the values of each field in your typed variable, enclosed between brackets [ ], because you convert your object to string before write it to the file.

Extracted from the documentation of Type (see help, I didn't remember but it is there!)



Late, when you read, you get a string and it's not possible to convert a string to an object.

Sounds strange, that, blitz convert an object to a string and afterwards couldn't reverse that string to an object again, but, I'm sorry, blitz don't do it.

So I agree with the solution given by Terry


If you still want, you should write the file the way you do, but when you read the file back, you have to parse the fields one by one, analyzing the string, looking for commas, and padding the first and the last element of the string (they are square brackets).

In your example, the string (second field) is null and all the integers are 0, so your strings look like: [0,"",0,0,0,0,0]

If you inspect your file with (notepad) you recognize the strings part, but they are separated by a 4 byte (no sense in ascii) because is an integer (4 bytes) that blitz write with the length of the string that is at their side. When you read the file, that weird part, is done by blitz and you get the strings back.

Extracted from the help of WriteString (again I didn't remember that!):



best regards

Juan

Thanks for the info folks.
Its true what you said almeida. And the solution given by you terry, i already use it. But thanks anyway for comfurning my idea. The major problem was indeed the way Blitz is handeling this string format. And thanks for giving me the awnser why its not working. I was wondering about that.

Anyway its stupid that Blitz permits it to write it to a file and converting it for you. but not converting it back. I try to program as mutch as possible using OOP. So the program is neet and tide.