In some cases, a so-called constructed decoder is useful. The main advantage is that it introduces some validation logic, making it possible to evaluate the order of the arriving records. For instance, suppose the incoming files contain one header and one trailer which must be present at the file start and end, in order for the file to be accepted. In between, data records may or may not be present. The data records can be of two types. Headers and trailers are considered to be records as well, so there are actually four record types in this format definition.
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| Code Block |
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encoder Total: out_map( TypeA_out ),
out_map( TypeB_out ),
out_map( Header_out ),
out_map( Trailer_out ); |
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