Compaq DEC Text Processing Utility AA-PWCBD-TE - Manual (Page 18)

Overview of the DEC Text Processing Utility
1.4 DECTPU Language
1.4.1 Data Types
The DECTPU language has an extensive set of data types. You use data types to
interpret the meaning of the contents of a variable. Unlike many languages, the
DECTPU language has no declarative statement to enforce which data type must
be assigned to a variable. A variable in DECTPU assumes a data type when it is
used in an assignment statement. For example, the following statement assigns
a string data type to the variable this_var:
this_var := ’This can be a string of your choice.’;
The following statement assigns a window data type to the variable x. The
window occupies 15 lines on the screen, starting at line 1, and the status line is
off (not displayed).
x := CREATE_WINDOW (1, 15, OFF);
Many of the DECTPU data types (for example, learn and pattern) are different
from the data types usually found in programming languages. See the DEC Text
Processing Reference Manual for the keywords used to specify data types. See
Chapter 3 of this manual for a discussion of DECTPU data types.
1.4.2 Language Declarations
DECTPU language declarations include the following:
• Module declaration (MODULE/IDENT/ENDMODULE)
• Procedure declaration (PROCEDURE/ENDPROCEDURE)
• Constant declaration (CONSTANT)
• Global variable declaration (VARIABLE)
• Local variable declaration (LOCAL)
See Chapter 4 of this manual for a discussion of DECTPU language declarations.
1.4.3 Language Statements
DECTPU language statements include the following:
• Assignment statement ( := )
• Repetitive statement (LOOP/EXITIF/ENDLOOP)
• Conditional statement (IF/THEN/ELSE/ENDIF)
• Case statement (CASE/ENDCASE)
• Error statement (ON_ERROR/ENDON_ERROR)
See Chapter 4 of this manual for a discussion of DECTPU language statements.
1.4.4 Built-In Procedures
The DECTPU language has many built-in procedures that perform functions such
as screen management, key definition, text manipulation, and program execution.
You can use built-in procedures to create your own procedures. You can also
invoke built-in procedures from within EVE. The DEC Text Processing Utility
Reference Manual contains a description of each of the DECTPU built-in
procedures.
1–6 Overview of the DEC Text Processing Utility