Pascal ALLBASE/SQL application programs have the same stages of
development as any application program. They originate as
Pascal source code files that are subsequently compiled with the
Pascal compiler and linked by the system linker to create an
executable program file. The development of ALLBASE/SQL programs,
however, requires that you preprocess those portions of the
program that contain SQL commands before compilation.
In the case illustrated in Figure 2-1 “Developing a Pascal ALLBASE/SQL Program”, the ALLBASE/SQL Pascal
program consists of one source file and, optionally, one or more
include files. The preprocessor merges any user include file
into the source program, and preprocesses it. The result is a
modified source code file and several preprocessor-generated
include files. These preprocessor include files contain all of
the definitions of variables used by any Pascal statements in
the modified source code file. These two files are then
compiled to produce an object code file, and linked to produce
an executable program file, in the same manner as any other
Pascal program.
In other cases, the ALLBASE/SQL application program might consist of
a main program and one or more subprograms in separate files.
In these cases, only source files containing embedded SQL code
need to be preprocessed, as illustrated in Figure 2-2. However,
each program file which contains embedded SQL code must be
preprocessed and compiled before the next program file is
preprocessed. Separately preprocessed program files that are
not immediately compiled will write over each other's
preprocessor created include files and consequently create an
error when compiled. You invoke the Pascal compiler as many
times as necessary to create the desired number of object code
modules. The files output by the Pascal preprocessor are
treated just as any other compiler input files at compile time.
During any invocation, the Pascal preprocessor can access only
one DBEnvironment. Therefore programs that access multiple
DBEnvironments must be divided into multiple subprograms, each
of which accesses only one DBEnvironment. Subprograms that
access the same DBEnvironment may be preprocessed and compiled
separately or jointly. The preprocessor stores a module in each
DBEnvironment accessed for each preprocessor invocation.
You can also create separate subprograms that all access the
same DBEnvironment. Each subprogram may again be preprocessed
and compiled separately or jointly. In this case, the
preprocessor stores multiple modules in one DBEnvironment. Each
module consists of sections with each section representing one
SQL command.
The criteria governing the division of an application program
into subprograms is very application-dependent. As in the
development of any application program, factors such as program
size, program complexity, expected recompilation frequency, and
number of programmers affect how a program is subdivided. In
the case of ALLBASE/SQL Pascal application programs, the only
additional factors are as follows:
All code containing embedded SQL commands must be preprocessed.
The preprocessor can access only one DBEnvironment at a time.
Each separately preprocessed program or subprogram that accesses
the same DBEnvironment must have a unique OwnerName.ModuleName. The module name defaults to the
program or subroutine name if the user does not provide one. The
owner name defaults to the user's logon if the user does not
provide one.
The preprocessor can process only one file per invocation.
Each preprocessed subprogram must be compiled before the next
subprogram is preprocessed.
User include files cannot contain duplicate host variable type
declarations sections.
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