[Coco] new problem with unpack

[Aaron Wolfe]

Doh.. hit send before I explained.

Testing here shows that assignment will let you copy between any two
*arrays* regardless of the underlying data type.  I suspect it will
also work with user defined data types.  It will not allow you to
assign one primitive data type to a different primitive data type, or
to/from array to primitive.

This behavior seems to be in line with the text:

"Another use of the assignment statement is to copy the entire value of an
array or complex data structure to another array or complex data structure."

Notice they are specific to state each side must be either an array or
complex data structure..  so not a STRING as in your test.

However, you can copy from a string to a byte array or vice versa
using SIZE, ADDR, PEEK and POKE.  These tools will let you copy values
to/from anything, though its going to be a manual process.

-Aaron




On Tue, Nov 5, 2013 at 4:15 PM, Aaron Wolfe <aawolfe at gmail.com> wrote:
> FWIW - This works:
>
>
> BASE 0
>
> DIM a1(10):BYTE
> DIM a2(1):STRING[10]
> DIM i:INTEGER
>
> FOR i=0 TO 9
>    a1(i) = 65
> NEXT i
>
> a2 = a1
>
> PRINT a2(0)
>
> (prints AAAAAAAAAA)
>
>
>
> On Tue, Nov 5, 2013 at 2:51 PM, Wayne Campbell <asa.rand at gmail.com> wrote:
>> It appears that one of the features of Basic09 is not a feature after all.
>> According to the Basic09 Reference for OS-9 Level 2:
>>
>> Chapter 11: Basic09 Command Reference: LET
>> ================================================================================
>> Use BASIC09’s assignment function to copy entire arrays or complex data
>> structures to another array or complex data structure. The data structures
>> do not need to be of the same type or shape, but the size of the
>> destination structure must be the same as or larger than the source
>> structure. This means the assignment function can perform unusual type
>> conversions. For example, you can copy a string variable of 80 characters
>> into a one-dimensional array of 80 bytes.
>> ================================================================================
>>
>> In the Level 1 Basic09 Manual it says:
>>
>> Chapter 9: Program Statements and Structure: Assignment Statements: LET
>> ================================================================================
>> Another use of the assignment statement is to copy the entire value of an
>> array or complex data structure to another array or complex data structure.
>> The data structures do not have to have the same type or "shape". The only
>> restriction is that the size of the destination structure be the same or
>> larger than the source structure. In fact this type of assignment can be
>> used to perform unusual type conversions. For example, a string variable of
>> 80 characters can be copied to a one-dimensional array of 80 bytes.
>> ================================================================================
>>
>> Neither manual provides an example of this usage. I tried assigning a
>> string to an array and vice-versa. I even went back to OS-9 Level 2
>> original disk image and tried it with Basic09 01.00.01. The assignment does
>> not work in OS-9 or in NitrOS-9. It returns a ERROR #071. In ErrorCodes,
>> the message is:
>>
>> Error#: 71 Illegal Expression Type
>>
>> Here is a sample program to try. If you have a real CoCo2 or CoCo3, and you
>> run NitrOS-9 L1 or L2, please try this program. I need to know what happens
>> on the real hardware.
>>
>> PROCEDURE LETtest
>> (* Remember that the keyword LET is optional *)
>> (* This procedure will use assignments both with and without it *)
>> (* I tried inserting BASE 1 and changing arrayStr length to 11 *)
>> (* with no change in the result *)
>>
>> DIM array(10):BYTE
>> DIM arrayStr:STRING[10]
>> DIM posCount:INTEGER
>>
>> (* array will contain 0123456789 *)
>> FOR posCount:=1 TO 10
>>   array(posCount):=posCount-1
>> NEXT posCount
>>
>> arrayStr:=array \! error 71
>> PRINT arrayStr
>>
>> arrayStr:="9876543210"
>> LET array:=arrayStr \! error 71
>> FOR posCount:=1 TO 10
>>   PRINT array(posCount);
>> NEXT posCount
>> PRINT
>>
>> END
>>
>> Load errors:
>>
>> 00C4 ERROR #071 Illegal Expression Type
>> 00E4 ERROR #071 Illegal Expression Type
>>
>> Error lines:
>>
>> 00BD arrayStr:=array <- C4 is the <eol> token
>> 00C5 PRINT arrayStr
>>
>> 00DC LET array:=arrayStr <- E4 is the <eol> token
>> 00E5 FOR posCount:=1 TO 10
>>
>> Runtime error:
>>
>> ERROR #051 Line with Compiler Error
>>
>> So, while I am supposed to be able to do these types of assignments,
>> Basic09 does not, in fact, allow it. At least, not in VCC or in MESS. Note
>> that neither assignment statement shows an error in the editor. The syntax
>> is considered valid by Basic09's editor.
>>
>> I believe that this functionality may have existed in L1 Basic09
>> (v01.00.00), but I do not have a copy to test with. I do, however, have a
>> copy of v01.00.01. Using that one I found the same error occurs. It is as
>> though this feature never really existed, but it could be that whatever
>> changed between v01.00.00 and 01.00.01 took away this feature.
>>
>> I welcome any input that can help dispel this confusion. Does anyone else
>> on this list have experience with this form of assignment in Basic09?
>>
>> Wayne
>>
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