pTAL Guidelines for TAL Programmers

pTAL Guidelines for TAL Programmers—527256-002
3-1
3
Differences Between TAL and pTAL
This section describes the following features:
•
Address-Conversion Routines on page 3-1
•
Address-Type Variables on page 3-4
•
DO_PTAL Directive on page 3-5
•
Procedure Pointers on page 3-6
•
Dynamically Selected Procedure Calls on page 3-18
•
Overflow Traps on page 3-20
•
Returning From Function Procedures on page 3-27
Address-Conversion Routines
In pTAL and in D40 and later releases of TAL, you can use address-type conversion
routines.
The native compilers ensure that each variable to an address-type conversion routine
has the correct type for the referenced routine. For example, a native compiler reports
a syntax error if the data type of the argument to the $BADDR_TO_WADDR routine is
not BADDR.
The TAL compiler does not ensure that the data type of the argument to the address-
conversion routines is correct. For examples of the differences between errors
detected by TAL and errors detected by native compilers, see Address-Type Variables
on page 3-4.
pTAL and TAL accept the following address-conversion routines in Table 3-1
on
page 3-2.