ABAP Development under Unicode
Prior to Unicode the length of a character was exactly one byte, allowing implicit typecasts or memory-layout oriented programming. With Unicode this situation has changed: One character is no longer one byte, so that additional specifications have to be added to define the unit of measure for implicit or explicit references to (the length of) characters.
Character-like data in ABAP are always represented with the UTF-16 - standard (also used in Java or other development tools like Microsoft's Visual Basic); but this format is not related to the encoding of the underlying database.
A Unicode-enabled ABAP program (UP) is a program in which all Unicode checks are effective. Such a program returns the same results in a non-Unicode system (NUS) as in a Unicode system (US). In order to perform the relevant syntax checks, you must activate the Unicode flag in the screens of the program and class attributes.
In a US, you can only execute programs for which the Unicode flag is set. In future, the Unicode flag must be set for all SAP programs to enable them to run on a US. If the Unicode flag is set for a program, the syntax is checked and the program executed according to the rules described in this document, regardless of whether the system is a US or a NUS. From now on, the Unicode flag must be set for all new programs and classes that are created.
If the Unicode flag is not set, a program can only be executed in an NUS. The syntactical and semantic changes described below do not apply to such programs. However, you can use all language extensions that have been introduced in the process of the conversion to Unicode.
As a result of the modifications and restrictions associated with the Unicode flag, programs are executed in both Unicode and non-Unicode systems with the same semantics to a large degree. In rare cases, however, differences may occur. Programs that are designed to run on both systems therefore need to be tested on both platforms.
Other Changes
1. Bit Statements
2. Adding Field Sequences
3. Loops with VARY and VARYING
4. Creating Subroutines
5. Saving Programs
6. Assigning Types for GET/SET PARAMETER
7. Unreachable Statements
8. Function Modules with Incorrect Parameter Names
1. Bit Statements
Previously, the system checked for the bit statements SET BIT i OF f [TO g] and GET BIT i OF f [INTO g]whether the field f is character-type; X fields, X strings, and flat structures are usually regarded as character-type. For Unicode programs this is no longer useful, because the types X and XSTRING no longer count as character-type and the bit by bit access to character-type fields or structures is no longer platform-independent. Therefore, with these operations in Unicode programs, the field f must be type X or XSTRING.
For the bit mask operations f O x, f Z x, and f M x you could previously use all number-type and hence all character-type types for the left operand f. In Unicode programs, the f operand must now be type X or XSTRING.
2. Adding Field Sequences
When adding field sequences, restrictions apply to the following statements in Unicode:
ADD n1 THEN n2 UNTIL nz [ ACCORDING TO sel ] GIVING m ...
ADD n1 THEN n2 UNTIL nz TO m [ RANGE str ].
1. The operands n1, n2, and nz must be type-compatible with one another.
2. The distance between nz and n1 must be an integral multiple of the distance between n2 and n1.
3. A syntax or runtime error occurs if the fields n1, n2, and nz are not in a structure. This structure must be recognizable statically or its valid area must be marked explicitly using the RANGE addition.
4. At runtime, the system ensures that the RANGE area is not left.
ADD n1 FROM i1 GIVING m [ RANGE str ].
1. Field n1 must be within the structure. The structure must be explicitly defined using the RANGE addition if it is not recognizable statically.
2. For this variant, the system also checks at runtime whether n1 and the addressed values are within the structure.
3. Loops
Loops with the VARY or VARYING addition are also problematic in Unicode, since a type-a access to memory contents cannot be ensured and memory can be overwritten inadvertently.
DO ... VARYING f FROM f1 NEXT f2.
For this statement, the fields f, f1, and f2 must be type-compatible with each other. To prevent memory contents being overwritten, a RANGE for valid accesses is introduced implicitly or explicitly for the following statements:
DO ... TIMES VARYING f FROM f1 NEXT f2 [ RANGE f3 ].
WHILE ... VARY f FROM f1 NEXT f2 [ RANGE f3 ].
A syntax or runtime error is caused if f1 or f2 are not included in f3. If the RANGE addition is missing, it is defined implicitly from FROM f1 NEXT f2 as follows:
1. If both f1 and f2 are statically recognizable components of the same structure, the valid RANGE area is defined from the smallest structure that comprises f1 and f2.
2. A syntax error is triggered if it is recognizable statically that f1 and f2 are not part of the same structure.
3. A valid area must be defined explicitly using the RANGE addition if the connection between f1 and f2 is not recognizable statically.
If you specify a deep structure as the RANGE addition, the system checks for every loop pass that there are no field references, object references, tables, or strings in the area read.
4. Creating Subroutines
When automatically generating subroutines using the statement GENERATE SUBROUTINE POOL itab NAME name, the generated program inherits the content of the Unicode flag of the generating program.
5. Saving Programs
When automatically generating programs using the statement INSERT REPORT prog FROM itab, default values are set for the TRDIR entry as before. Amongst other things, this statement has the new addition UNICODE ENABLING uc, with which the Unicode flag of the inserted report receives the value of uc. If this addition is missing, the following applies:
1. A Unicode program creates a Unicode program.
2. A non-Unicode program in turn creates a non-Unicode program.
3. A non-Unicode program becomes a Unicode program if it is overwritten by a Unicode program.
4. A Unicode program remains a Unicode program if it is overwritten by a non-Unicode program.
6. Assigning Types for GET/SET PARAMETER
For the statements GET PARAMETER ID pid FIELD f and GET PARAMETER ID pid FIELD f, f must be character-type. You can use the EXPORT and IMPORT statements for storing non-character-type fields and structures.
7. Unreachable Statements
In Unicode programs, unreachable statements cause a syntax error. In non-Unicode programs, there was previously only a syntax warning.
8. Function Modules with Incorrect Parameter Names
In Unicode programs, calling a function module, whose parameter names are specified statically as a literal or constant, causes an exception that can be handled if an incorrect parameter name was specified. This only applies to function modules that are not called via Remote Function Call. In non-Unicode programs, an incorrect name was previously ignored.
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