Explanation of Compiler Workspace and What Affects It (61336)

SUMMARY

The information below shows what items affect compiler workspace, and some practices that can be used when compiler workspace must be increased.

The compiler workspace is displayed by the "Bytes Available" and "Bytes Free" lines given at the end of compilation. For more information on these lines, query on the following words:

Basic and bytes available and free and symbol table and workspace

This information applies to Microsoft QuickBasic versions 4.00, 4.00b, and 4.50 for MS-DOS; to Microsoft Basic Compiler versions 6.00 and 6.00b for MS-DOS and MS OS/2; and to Microsoft Basic Professional Development System (PDS) versions 7.00 and 7.10 for MS-DOS and MS OS/2.

MORE INFORMATION

The compiler workspace is made up of the line-number table, symbol table, and working storage for compiler code generation and optimization. Because of this, the compiler workspace is affected by such things as the length of variable, procedure, and line label names, and the number of lines in the program. The following paragraphs detail some of the things that affect the compiler workspace:

   Variable SUB,    Because variables go into the symbol table, they
   and FUNCTION     have a direct effect on compiler workspace.
   names
                    Each new variable has some initial overhead plus
                    additional overhead for each character in the
                    variable name. Once a variable is defined, it
                    has no extra effect on the compiler workspace no
                    matter how many times it is used again.

   Line numbers     Every line number decreases the compiler
                    workspace. Unlike variable and procedure names,
                    however, it does not matter how big a line
                    number is. The line number 10 takes just as
                    much compiler workspace as does the line number
                    10,000.

   Program lines    Each line in the program takes up some compiler
                    workspace. Two PRINT statements put on the same
                    line, such as

                       PRINT : PRINT

                    take up less compiler workspace than when the
                    statements are put on two separate lines, as in:

                       PRINT
                       PRINT

                    Extra blank lines between code have no effect on
                    compiler workspace. Therefore, the following
                    three lines of code take just as much compiler
                    workspace as do the previous two lines of code:

                       PRINT

                       PRINT

If a program is running out of compiler workspace (bytes available goes to zero), you can try each of the following to increase the workspace:

Break the code into multiple modules. This is the best solution from a structured programming point of view. Each module has the full compiler workspace available to it, and because code is taken out of the original program, compiler workspace will be used regained.
Put multiple statements on each line. Although not recommended for structured programming, moving multiple source lines onto a single line separated by a colon (:) will decrease the amount of compiler workspace being used.
Decrease the size of SUB, FUNCTION, and variable names. This will make the code less readable, but again can be used when compiler workspace is at a premium.